Juno is Ready to Tell Us What it Found at Jupiter

The tightly clustered storms that crowd Jupiter's polar regions are another of the gas giant's mysteries. In this image, cyclones the size of Earth bump up against each other at the south pole. Image: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles
The tightly clustered storms that crowd Jupiter's polar regions are another of the gas giant's mysteries. In this image, cyclones the size of Earth bump up against each other at the south pole. Image: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles

Even a casual observer can see how complex Jupiter might be. Its Great Red Spot is one of the most iconic objects in our Solar System. The Great Red Spot, which is a continuous storm 2 or 3 times as large as Earth, along with Jupiter’s easily-seen storm cloud belts, are visual clues that Jupiter is a complex place.

We’ve been observing the Great Red Spot for almost 200 years, so we’ve known for a long time that something special is happening at Jupiter. Now that the Juno probe is there, we’re finding that Jupiter might be a more surprising place than we thought.

“There is so much going on here that we didn’t expect that we have had to take a step back and begin to rethink of this as a whole new Jupiter.” – Scott Bolton, Juno’s Principal Investigator at the Southwest Research Institute.

So far, the stunning images delivered to us by the JunoCam have stolen the show. But Juno is a science mission, and the fantastic images we’re feasting on might stir the imagination, but it’s the science that’s at the heart of the mission.

Just one of the many beautiful images of Jupiter we're accustomed to seeing. NASA has invited interested citizens to process JunoCam images and has made them available for anyone to use. NASA / SwRI / MSSS / Gerald Eichstädt / Seán Doran © public domain
Just one of the many beautiful images of Jupiter we’re accustomed to seeing. NASA has invited interested citizens to process JunoCam images and has made them available for anyone to use. NASA / SwRI / MSSS / Gerald Eichstädt / Seán Doran © public domain

The Juno probe arrived at Jupiter in July 2016, and completed its first data-pass on August 27th, 2016. That pass took it to within 4,200 km of Jupiter’s cloud tops. Results from that first pass are being published in the journal Science and in Geophysical Research Letters.

Taken together, the results confirm what we might have guessed by just looking at Jupiter from afar: it is a stormy, complex, turbulent world.

“It was a long trip to get to Jupiter, but these first results already demonstrate it was well worth the journey.” – Diane Brown, Juno Program Executive.

“We are excited to share these early discoveries, which help us better understand what makes Jupiter so fascinating,” said Diane Brown, Juno program executive at NASA Headquarters in Washington. “It was a long trip to get to Jupiter, but these first results already demonstrate it was well worth the journey.”

Jupiter’s Magnetic Field

We’ve known for a long time that Jupiter has the most powerful magnetic field in the Solar System. In fact, the magnetic field is what shaped the design of the Juno probe, and the profile of the mission itself. Juno’s Magnetometer Investigation (MAG) has measured the gas giant’s magnetosphere up close, and these measurements tell us that the magnetic field is even stronger than anticipated, and its shape is more irregular as well. At 7.66 Gauss, the field is about 10 times more powerful than Earth.

The irregularities in the magnetic field are an indication that the field is generated closer to the surface than thought. Earth generates its magnetic field from it its rotating core, but because Jupiter’s is “lumpy”, or stronger in some regions than in others, the gas giant’s magnetic field might be generated above its metallic hydrogen layer.

Results from Juno's first data-pass suggest that Jupiter's powerful magnetic field is generated closer to the surface than previously thought. It may be generated above the core of metallic hydrogen. Image: By Kelvinsong - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=31764016
Results from Juno’s first data-pass suggest that Jupiter’s powerful magnetic field is generated closer to the surface than previously thought. It may be generated above the core of metallic hydrogen. Image: By Kelvinsong – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=31764016

“Juno is giving us a view of the magnetic field close to Jupiter that we’ve never had before,” – Jack Connerney, Juno Deputy Principal Investigator

“Juno is giving us a view of the magnetic field close to Jupiter that we’ve never had before,” said Jack Connerney, Juno deputy principal investigator and the lead for the mission’s magnetic field investigation at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Already we see that the magnetic field looks lumpy: it is stronger in some places and weaker in others. This uneven distribution suggests that the field might be generated by dynamo action closer to the surface, above the layer of metallic hydrogen. Every flyby we execute gets us closer to determining where and how Jupiter’s dynamo works.”

Jupiter’s Atmosphere

Juno’s Microwave Radiometer (MWR) is designed to probe Jupiter’s thick atmosphere. It can detect the thermal microwave radiation in the atmosphere, both at the surface, and much deeper. Data from the MWR shows us that the storm belts are mysteries themselves.

This artist's illustration shows Juno's Microwave Radiometer observing deep into Jupiter's atmosphere. The image shows real data from the 6 MWR channels, arranged by wavelength. Credit: NASA/SwRI/JPL
This artist’s illustration shows Juno’s Microwave Radiometer observing deep into Jupiter’s atmosphere. The image shows real data from the 6 MWR channels, arranged by wavelength. Credit: NASA/SwRI/JPL

The belts near Jupiter’s equator extend deep into the atmosphere, while other belts seem to evolve and transform into other structures. The MWR can probe a few hundred kilometers into the atmosphere, where it has found variable and increasing amounts of ammonia to that depth.

Polar Regions and Auroras

Jupiter is home to intense aurora activity at both poles. One of Juno’s mission goals is to study those auroras and the powerful polar magnetic fields that create them. Initial observations from Juno suggest that they are formed differently than Earthly auroras.

Juno is in a unique position to study the magnetosphere and the auroras. Its elongated polar orbit allows it to span the entire magnetosphere all the way from the bow shock to the planet itself.

The tilt of Juno's orbit relative to Jupiter changes over the course of the mission, sending the spacecraft increasingly deeper into the planet's intense radiation belts. This also gives Juno the ability to study the structure of the magnetosphere. Credit: NASA/JPL-Caltech
The tilt of Juno’s orbit relative to Jupiter changes over the course of the mission, sending the spacecraft increasingly deeper into the planet’s intense radiation belts. This also gives Juno the ability to study the structure of the magnetosphere. Credit: NASA/JPL-Caltech

According to the paper detailing the initial data on Jupiter’s magnetosphere an auroras, many of the observations have “terrestrial analogs.” But other aspects are very Jovian, and have no counterpart on Earth.

“…a radically different conceptual model of Jupiter’s interaction with its space environment.” – from J. E. P. Connerney et. al., 2017

As the authors say in their summary, “We observed plasmas upwelling from the ionosphere, providing a mechanism whereby Jupiter helps populate its magnetosphere. The weakness of the magnetic field-aligned electric currents associated with the main aurora and the broadly distributed nature of electron beaming in the polar caps suggest a radically different conceptual model of Jupiter’s interaction with its space environment.”

Polar Storms

JunoCam has also found some puzzling features in Jupiter’s atmosphere. The poles themselves are populated by densely clustered, swirling storms the size of Earth. Since they’ve only been observed briefly, there are a host of unanswered questions about them.

“We’re puzzled as to how they could be formed, how stable the configuration is, and why Jupiter’s north pole doesn’t look like the south pole.” – Scott Bolton, Juno’s Principal Investigator at the Southwest Research Institute

“We’re puzzled as to how they could be formed, how stable the configuration is, and why Jupiter’s north pole doesn’t look like the south pole,” said Bolton. “We’re questioning whether this is a dynamic system, and are we seeing just one stage, and over the next year, we’re going to watch it disappear, or is this a stable configuration and these storms are circulating around one another?”

The tightly clustered storms that crowd Jupiter's polar regions are another of the gas giant's mysteries. In this image, cyclones the size of Earth bump up against each other at the south pole. Image:  NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles
The tightly clustered storms that crowd Jupiter’s polar regions are another of the gas giant’s mysteries. In this image, cyclones the size of Earth bump up against each other at the south pole. Image: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles

The Great Red Spot: Juno’s Next Target

Juno’s purposeful orbit takes it extremely close to the cloud tops, where it can perform powerful science. But the orbit also takes it a long way from Jupiter. Every 53 days it takes another plunge at Jupiter, where it gathers its next set of observations.

“Every 53 days, we go screaming by Jupiter, get doused by a fire hose of Jovian science, and there is always something new.” – Scott Bolton, Juno’s Principal Investigator at the Southwest Research Institute.

“Every 53 days, we go screaming by Jupiter, get doused by a fire hose of Jovian science, and there is always something new,” said Bolton. “On our next flyby on July 11, we will fly directly over one of the most iconic features in the entire solar system — one that every school kid knows — Jupiter’s Great Red Spot. If anybody is going to get to the bottom of what is going on below those mammoth swirling crimson cloud tops, it’s Juno and her cloud-piercing science instruments.”

The JunoCam's next target: Jupiter's iconic Great Red Spot. Image:  NASA/JPL-Caltech/SwRI/MSSS/Roman Tkachenko
Juno’s next target: Jupiter’s iconic Great Red Spot. Image: NASA/JPL-Caltech/SwRI/MSSS/Roman Tkachenko

During each pass, Juno collects about 6 megabytes of data, which it sends back to Earth via the Deep Space Network. After that, the data is analyzed and published.

Juno has many more fly-bys of Jupiter before it’s sent to its end in the atmosphere of Jupiter. We can expect many more surprises, and hopefully some answers, between now and then.

Scientists Propose a New Kind of Planet: A Smashed Up Torus of Hot Vaporized Rock

Artist's impression of a Mars-sized object crashing into the Earth, starting the process that eventually created our Moon. Credit: Joe Tucciarone
Artist's impression of a Mars-sized object crashing into the Earth, starting the process that eventually created our Moon. Credit: Joe Tucciarone

There’s a new type of planet in town, though you won’t find it in well-aged solar systems like our own. It’s more of a stage of formation that planets like Earth can go through. And its existence helps explain the relationship between Earth and our Moon.

The new type of planet is a huge, spinning, donut-shaped mass of hot, vaporized rock, formed as planet-sized objects smash into each other. The pair of scientists behind the study explaining this new planet type have named it a ‘synestia.’ Simon Lock, a graduate student at Harvard University, and Sarah Stewart, a professor in the Department of Earth and Planetary Sciences at the University of California, Davis, say that Earth was at one time a synestia.

Rocky planets like Earth are accreted from smaller bodies over time. Objects with high energy and high angular momentum could form a synestia, a transient stage in planetary formation where vaporized rock orbits the rest of the body. In this image, each of the three stages has the same mass. Image: Simon Lock, Harvard University
Rocky planets like Earth are accreted from smaller bodies over time. Objects with high energy and high angular momentum could form a synestia, a transient stage in planetary formation where vaporized rock orbits the rest of the body. In this image, each of the three stages has the same mass. Image: Simon Lock, Harvard University

The current theory of planetary formation goes like this: When a star forms, the left-over material is in motion around the star. This left-over material is called a protoplanetary disk. The material coagulates into larger bodies as the smaller ones collide and join together.

As the bodies get larger and larger, the force of their collisions becomes greater and greater, and when two large bodies collided, their rocky material melts. Then, the newly created body cools, and becomes spherical. It’s understood that this is how Earth and the other rocky planets in our Solar System formed.

Lock and Stewart looked at this process and asked what would happen if the resulting body was spinning quickly.

When a body is spinning, the law of conservation of angular momentum comes into play. That law says that a spinning body will spin until an external torque slows it down. The often-used example from figure skating helps explain this.

If you’ve ever watched figure skaters, and who hasn’t, their actions are very instructive. When a single skater is spinning rapidly, she stretches out her arms to slow the rate of spin. When she folds her arms back into her body, she speeds up again. Her angular momentum is conserved.

This short video shows figure skaters and physics in action.

If you don’t like figure skating, this one uses the Earth to explain angular momentum.

Now take the example from a pair of figure skaters. When they’re both turning, and the two of them join together by holding each other’s hands and arms, their angular momentum is added together and conserved.

Replace two figure skaters with two planets, and this is what the two scientists behind the study wanted to model. What would happen if two large bodies with high energy and high angular momentum collided with each other?

If the two bodies had high enough temperatures and high enough angular momentum, a new type of planetary structure would form: the synestia. “We looked at the statistics of giant impacts, and we found that they can form a completely new structure,” Stewart said.

“We looked at the statistics of giant impacts, and we found that they can form a completely new structure.” – Professor Sarah Stewart, Department of Earth and Planetary Sciences at the University of California, Davis.

As explained in a press release from the UC Davis, for a synestia to form, some of the vaporized material from the collision must go into orbit. When a sphere is solid, every point on it is rotating at the same rate, if not the same speed. But when some of the material is vaporized, its volume expands. If it expands enough, and if its moving fast enough, it leaves orbit and forms a huge disc-shaped synestia.

Other theories have proposed that two large enough bodies could form an orbiting molten mass after colliding. But if the two bodies had high enough energy and temperature to vaporize some of the rock, the resulting synestia would occupy a much larger space.

“The main issue with looking for synestias around other stars is that they don’t last a long time. These are transient, evolving objects that are made during planet formation.” – Professor Sarah Stewart, UC Davis.

These synestias likely wouldn’t last very long. They would cool quickly and condense back into rocky bodies. For a body the size of Earth, the synestia might only last one hundred years.

The synestia structure sheds some light on how moons are formed. The Earth and the Moon are very similar in terms of composition, so it’s likely they formed as a result of a collision. It’s possible that the Earth and Moon formed from the same synestia.

These synestias have been modelled, but they haven’t been observed. However, the James Webb Space Telescope will have the power to peer into protoplanetary disks and watch planets forming. Will it observe a synestia?

“These are transient, evolving objects that are made during planet formation.” – Professor Sarah Stewart, UC Davis

In an email exchange with Universe Today, Dr. Sarah Stewart of UC Davis, one of the scientists behind the study, told us that “The main issue with looking for synestias around other stars is that they don’t last a long time. These are transient, evolving objects that are made during planet formation.”

“So the best bet for finding a rocky synestia is young systems where the body is close to the star. For gas giant planets, they may form a synestia for a period of their formation. We are getting close to being able to image circumplanetary disks in other star systems.”

Once we have the ability to observe planets forming in their circumstellar disks, we may find that synestias are more common than rare. In fact, planets may go through the synestia stage multiple times. Dr. Stewart told us that “Based on the statistics presented in our paper, we expect that most (more than half) of rocky planets that form in a manner similar to Earth became synestias one or more times during the giant impact stage of accretion.”

Dinosaur Killing Asteroid Hit in Exactly the Wrong Place

When an asteroid struck the Yucatan region about 66 million years ago, it triggered the extinction of the dinosaurs. ESA's Hera mission is visiting the smallest spacerock ever as part of our effort to not get creamed by an asteroid. Credit: NASA/Don Davis
When an asteroid struck the Yucatan region about 66 million years ago, it triggered the extinction of the dinosaurs. ESA's Hera mission is visiting the smallest spacerock ever as part of our effort to not get creamed by an asteroid. Credit: NASA/Don Davis

The asteroid that struck Earth about 66 million years ago and led to the mass extinction of dinosaurs may have hit one of the worst places possible as far as life on Earth was concerned. When it struck, the resulting cataclysm choked the atmosphere with sulphur, which blocked out the Sun. Without the Sun, the food chain collapsed, and it was bye-bye dinosaurs, and bye-bye most of the other life on Earth, too.

But, as it turns out, if it had struck a few moments earlier or later, it would not have hit the Yucatan, and things may have turned out differently. Why? Because of the concentration of the mineral gypsum in that area.

The place where the asteroid hit Earth is called the Chicxulub Crater, and scientists have been studying that area to try to learn more about the impact event that altered the course of life on Earth. An upcoming BBC documentary called “The Day The Dinosaurs Died,” focuses on what happened when the asteroid struck. Drill-core samples from the Yucatan area help explain the events that followed the impact.

The drilling rig off the coast of the Yucatan. The rig was there in the Spring of 2016 obtaining samples from the seafloor. Image: BBC/Barcroft Productions.
The drilling rig off the coast of the Yucatan. The rig was there in the Spring of 2016 obtaining samples from the seafloor. Image: BBC/Barcroft Productions.

The core samples, which are from as deep as 1300 m beneath the Gulf of Mexico, are from a feature called the peak ring.

When the asteroid struck Earth, it excavated a crater 100 km across and 30 km deep. This crater collapsed into a wider but shallower crater 200 km across and a few km deep. Then the center of the crater rebounded, and collapsed again, leaving the peak ring feature. The Chicxulub crater is now partly under water, and that’s where a drilling rig was set up to take samples.

The peak ring is at the center of the crater, offshore of the Yucatan Peninsula. Image: NASA/BBC
The peak ring is at the center of the crater, offshore of the Yucatan Peninsula. Image: NASA/BBC

The core samples revealed rock that has been heavily fractured and altered by immense pressures. The same impact that altered those rocks would have generated an enormous amount of heat, and that heat created an enormous cloud of sulphur from the vaporized gypsum. That cloud persisted, which led to a global winter. Temperatures dropped, plant growth came to a standstill, and the course of events on Earth were altered forever.

“Had the asteroid struck a few moments earlier or later, rather than hitting shallow coastal waters it might have hit deep ocean,” documentary co-presenter Ben Garrod told the BBC.

“This is where we get to the great irony of the story – because in the end it wasn’t the size of the asteroid, the scale of blast, or even its global reach that made dinosaurs extinct – it was where the impact happened,” said Ben Garrod, who presents “The Day The Dinosaurs Died” with Alice Roberts.

“An impact in the nearby Atlantic or Pacific oceans would have meant much less vaporised rock – including the deadly gypsum. The cloud would have been less dense and sunlight could still have reached the planet’s surface, meaning what happened next might have been avoided,” said Garrod.

In the documentary, host Alice Roberts will also visit a quarry in New Jersey, where fossil evidence shows a massive die-off in a very short period of time. In fact, these creatures could have died on the very day that the asteroid struck.

The core samples from the drilling rig show rocks that were subjected to immense heat and pressure at the time of the impact. Image: Barcroft Productions/BBC
The core samples from the drilling rig show rocks that were subjected to immense heat and pressure at the time of the impact. Image: Barcroft Productions/BBC

“All these fossils occur in a layer no more than 10cm thick,” palaeontologist Ken Lacovara tells Alice. “They died suddenly and were buried quickly. It tells us this is a moment in geological time. That’s days, weeks, maybe months. But this is not thousands of years; it’s not hundreds of thousands of years. This is essentially an instantaneous event.”

There’s lots of evidence showing that an asteroid struck Earth about 66 million years ago, causing widespread extinction. NASA satellite images clearly show crater features, now obscured by 66 million years of geological activity, but still visible.

There’s also what’s called the K-T Boundary, or Cretaceous-Tertiary Boundary. It’s a geological signature dating to 66 million years ago, which marks the end of the Cretaceous Period. In that boundary is a layer of iridium at very high concentrations, much higher than is normally present in the Earth’s crust. Since iridium is much more abundant in asteroids, the conclusion is that it was probably deposited by an asteroid.

But this is the first evidence that shows how critical the actual location of the event may have been. If it had not struck where it had, dinosaurs may never have gone extinct, you and I would not be here, and things on Earth could look much different.

It might sound like the stuff of science fiction, but who knows? Maybe a race of intelligent lizards might already have mastered interstellar travel.

Mysterious Flashes Coming From Earth That Puzzled Carl Sagan Finally Have An Explanation

Sun glints off atmospheric ice crystals (circled in red) in this view captured by NASA's EPIC instrument on NOAA's DISCOVR satellite. Image Credit: NASA's Goddard Space Flight Center
Sun glints off atmospheric ice crystals (circled in red) in this view captured by NASA's EPIC instrument on NOAA's DISCOVR satellite. Image Credit: NASA's Goddard Space Flight Center

Back in 1993, Carl Sagan encountered a puzzle. The Galileo spacecraft spotted flashes coming from Earth, and nobody could figure out what they were. They called them ‘specular reflections’ and they appeared over ocean areas but not over land.

The images were taken by the Galileo space probe during one of its gravitational-assist flybys of Earth. Galileo was on its way to Jupiter, and its cameras were turned back to look at Earth from a distance of about 2 million km. This was all part of an experiment aimed at finding life on other worlds. What would a living world look like from a distance? Why not use Earth as an example?

Fast-forward to 2015, when the National Oceanographic and Atmospheric Administration (NOAA) launched the Deep Space Climate Observatory (DSCOVER) spacecraft. DSCOVER’s job is to orbit Earth a million miles away and to warn us of dangerous space weather. NASA has a powerful instrument on DSCOVER called the Earth Polychromatic Imaging Camera (EPIC.)

Every hour, EPIC takes images of the sunlit side of Earth, and these images can be viewed on the EPIC website. (Check it out, it’s super cool.) People began to notice the same flashes Sagan saw, hundreds of them in one year. Scientists in charge of EPIC started noticing them, too.

One of the scientists is Alexander Marshak, DSCOVR deputy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. At first, he noticed them only over ocean areas, the same as Sagan did 25 years ago. Only after Marshak began investigating them did he realize that Sagan had seen them too.

Back in 1993, Sagan and his colleagues wrote a paper discussing the results from Galileo’s examination of Earth. This is what they said about the reflections they noticed: “Large expanses of blue ocean and apparent coastlines are present, and close examination of the images shows a region of [mirror-like] reflection in ocean but not on land.”

Marshak surmised that there could be a simple explanation for the flashes. Sunlight hits a smooth part of an ocean or lake, and reflects directly back to the sensor, like taking a flash-picture in a mirror. Was it really that much of a mystery?

When Marshak and his colleagues took another look at the Galileo images showing the flashes, they found something that Sagan missed back in 1993: The flashes appeared over land masses as well. And when they looked at the EPIC images, they found flashes over land masses. So a simple explanation like light reflecting off the oceans was no longer in play.

“We found quite a few very bright flashes over land as well.” – Alexander Marshak, DSCOVR Deputy Project Scientist

“We found quite a few very bright flashes over land as well,” he said. “When I first saw it I thought maybe there was some water there, or a lake the sun reflects off of. But the glint is pretty big, so it wasn’t that.”

But something was causing the flashes, something reflective. Marshak and his colleagues, Tamas Varnai of the University of Maryland, Baltimore County, and Alexander Kostinski of Michigan Technological University, thought of other ways that water could cause the flashes.

The primary candidate was ice particles high in Earth’s atmosphere. High-altitude cirrus clouds contain tiny ice platelets that are horizontally aligned almost perfectly. The trio of scientists did some experiments to find the cause of the flashes, and published their results in a new paper published in Geophysical Research Letters.

“Lightning doesn’t care about the sun and EPIC’s location.” – Alexander Marshak, DSCOVR Deputy Project Scientist

As their study details, they first catalogued all of the reflective glints that EPIC found over land; 866 of them in a 14 month period from June 2015 to August 2016. If these flashes were caused by reflection, then they would only appear on locations on the globe where the angle between the Sun and Earth matched the angle between the DSCOVER spacecraft and Earth. As the catalogued the 866 glints, they found that the angle did match.

This ruled out something like lightning as the cause of the flashes. But as they continued their work plotting the angles, they came to another conclusion: the flashes were sunlight reflecting off of horizontal ice crystals in the atmosphere. Other instruments on DSCOVR confirmed that the reflections were coming from high in the atmosphere, rather than from somewhere on the surface.

“The source of the flashes is definitely not on the ground. It’s definitely ice, and most likely solar reflection off of horizontally oriented particles.” -Alexander Marshak, DSCOVR Deputy Project Scientist

Mystery solved. But as is often the case with science, answering one question leads to a couple other questions. Could detecting these glints be used in the study of exoplanets somehow? But that’s one for the space science community to answer.

As for Marshak, he’s an Earth scientist. He’s investigating how common these horizontal ice particles are, and what effect they have on sunlight. If that impact is measurable, then it could be included in climate modelling to try to understand how Earth retains and sheds heat.

Sources:

New Estimate Puts the Supernova Killzone Within 50 Light-Years of Earth

Composite Spitzer, Hubble, and Chandra image of supernova remnant Cassiopeia A. A new study shows that a supernova as far away as 50 light years could have devastating effects on life on Earth. (NASA/JPL-Caltech/STScI/CXC/SAO)
Composite Spitzer, Hubble, and Chandra image of supernova remnant Cassiopeia A. A new study shows that a supernova as far away as 50 light years could have devastating effects on life on Earth. (NASA/JPL-Caltech/STScI/CXC/SAO)

There are a lot of ways that life on Earth could come to an end: an asteroid strike, global climate catastrophe, or nuclear war are among them. But perhaps the most haunting would be death by supernova, because there’s absolutely nothing we could do about it. We’d be sitting ducks.

New research suggest that a supernova’s kill zone is bigger than we thought; about 25 light years bigger, to be exact.

Iron in the Ocean

In 2016, researchers confirmed that Earth has been hit with the effects from multiple supernovae. The presence of iron 60 in the seabed confirms it. Iron 60 is an isotope of iron produced in supernova explosions, and it was found in fossilized bacteria in sediments on the ocean floor. Those iron 60 remnants suggest that two supernovae exploded near our solar system, one between 6.5 to 8.7 million years ago, and another as recently as 2 million years ago.

Iron 60 is extremely rare here on Earth because it has a short half life of 2.6 million years. Any of the iron 60 created at the time of Earth’s formation would have decayed into something else by now. So when researchers found the iron 60 on the ocean floor, they reasoned that it must have another source, and that logical source is a supernova.

This evidence was the smoking gun for the idea that Earth has been struck by supernovae. But the questions it begs are, what effect did that supernova have on life on Earth? And how far away do we have to be from a supernova to be safe?

“…we can look for events in the history of the Earth that might be connected to them (supernova events).” – Dr. Adrian Melott, Astrophysicist, University of Kansas.

In a press release from the University of Kansas, astrophysicist Adrian Melott talked about recent research into supernovae and the effects they can have on Earth. “This research essentially proves that certain events happened in the not-too-distant past,” said Melott, a KU professor of physics and astronomy. “They make it clear approximately when they happened and how far away they were. Knowing that, we can consider what the effect may have been with definite numbers. Then we can look for events in the history of the Earth that might be connected to them.”

Earlier work suggested that a supernova kill zone is about 25-30 light years. If a supernova exploded that close to Earth, it would trigger a mass extinction. Bye-bye humanity. But new work suggests that 25 light years is an under-estimation, and that a supernova 50 light years away would be powerful enough to cause a mass extinction.

Supernovae: A Force Driving Evolution?

But extinction is just one effect a supernova could have on Earth. Supernovae can have other effects, and they might not all be negative. It’s possible that a supernovae about 2.6 million years ago even drove human evolution.

“Our local research group is working on figuring out what the effects were likely to have been,” Melott said. “We really don’t know. The events weren’t close enough to cause a big mass extinction or severe effects, but not so far away that we can ignore them either. We’re trying to decide if we should expect to have seen any effects on the ground on the Earth.”

Melott and his colleagues have written a new paper that focuses on the effects a supernova might have on Earth. In a new paper titled “A SUPERNOVA AT 50 PC: EFFECTS ON THE EARTH’S ATMOSPHERE AND BIOTA”, Melott and a team of researchers tried to shed light on Earth-supernova interactions.

The Local Bubble

There are a number of variables that come into play when trying to determine the effects of a supernova, and one of them is the idea of the Local Bubble. The Local Bubble itself is the result of one or more supernova explosion that occurred as long as 20 million years ago. The Local Bubble is a 300 light year diameter bubble of expanding gas in our arm of the Milky Way galaxy, where our Solar System currently resides. We’ve been travelling through it for the last five to ten million years. Inside this bubble, the magnetic field is weak and disordered.

Melott’s paper focused on the effects that a supernova about 2.6 million years ago would have on Earth in two instances: while both were within the Local Bubble, and while both were outside the Local Bubble.

The disrupted magnetic field inside the Local Bubble can in essence magnify the effects a supernova can have on Earth. It can increase the cosmic rays that reach Earth by a factor of a few hundred. This can increase the ionization in the Earth’s troposphere, which mean that life on Earth would be hit with more radiation.

Outside the Local Bubble, the magnetic field is more ordered, so the effect depends on the orientation of the magnetic field. The ordered magnetic field can either aim more radiation at Earth, or it could in a sense deflect it, much like our magnetosphere does now.

Focusing on the Pleistocene

Melott’s paper looks into the connection between the supernova and the global cooling that took place during the Pleistocene epoch about 2.6 million years ago. There was no mass extinction at that time, but there was an elevated extinction rate.

According to the paper, it’s possible that increased radiation from a supernova could have changed cloud formation, which would help explain a number of things that happened at the beginning of the Pleistocene. There was increased glaciation, increased species extinction, and Africa grew cooler and changed from predominantly forests to semi-arid grasslands.

Cancer and Mutation

As the paper concludes, it is difficult to know exactly what happened to Earth 2.6 million years ago when a supernova exploded in our vicinity. And it’s difficult to pinpoint an exact distance at which life on Earth would be in trouble.

But high levels of radiation from a supernova could increase the cancer rate, which could contribute to extinction. It could also increase the mutation rate, another contributor to extinction. At the highest levels modeled in this study, the radiation could even reach one kilometer deep into the ocean.

There is no real record of increased cancer in the fossil record, so this study is hampered in that sense. But overall, it’s a fascinating look at the possible interplay between cosmic events and how we and the rest of life on Earth evolved.

Sources:

Early Earth Was Almost Entirely Underwater, With Just A Few Islands

Earth's Hadean Eon is a bit of a mystery to us, because geologic evidence from that time is scarce. Researchers at the Australian National University have used tiny zircon grains to get a better picture of early Earth. Credit: NASA
Earth's Hadean Eon is a bit of a mystery to us, because geologic evidence from that time is scarce. Researchers at the Australian National University have used tiny zircon grains to get a better picture of early Earth. Credit: NASA

It might seem unlikely, but tiny grains of minerals can help tell the story of early Earth. And researchers studying those grains say that 4.4 billion years ago, Earth was a barren, mountainless place, and almost everything was under water. Only a handful of islands poked above the surface.

Continue reading “Early Earth Was Almost Entirely Underwater, With Just A Few Islands”

Rise of the Super Telescopes: Why We Build Them

This illustration shows what the Giant Magellan Telescope will look like when it comes online. The fifth of its seven mirror segments is being cast now. Each of the segments is a 20 ton piece of glass. Image: Giant Magellan
This illustration shows what the Giant Magellan Telescope will look like when it comes online. Each of its mirror segments is a 20 ton piece of glass. Image: Giant Magellan Telescope – GMTO Corporation

One night 400 years ago, Galileo pointed his 2 inch telescope at Jupiter and spotted 3 of its moons. On subsequent nights, he spotted another, and saw one of the moons disappear behind Jupiter. With those simple observations, he propelled human understanding onto a path it still travels.

Galileo’s observations set off a revolution in astronomy. Prior to his observations of Jupiter’s moons, the prevailing belief was that the entire Universe rotated around the Earth, which lay at the center of everything. That’s a delightfully childish viewpoint, in retrospect, but it was dogma at the time.

Until Galileo’s telescope, this Earth-centric viewpoint, called Aristotelian cosmology, made sense. To all appearances, we were at the center of the action. Which just goes to show you how wrong we can be.

But once it became clear that Jupiter had other bodies orbiting it, our cherished position at the center of the Universe was doomed.

Galileo Galilei set off a revolution in astronomy when he used his telescope to observe moons orbiting Jupiter. By Justus Sustermans - http://www.nmm.ac.uk/mag/pages/mnuExplore/PaintingDetail.cfm?ID=BHC2700, Public Domain, https://commons.wikimedia.org/w/index.php?curid=230543
Galileo Galilei set off a revolution in astronomy when he used his telescope to observe moons orbiting Jupiter. By Justus Sustermans – http://www.nmm.ac.uk/mag/pages/mnuExplore/PaintingDetail.cfm?ID=BHC2700, Public Domain, https://commons.wikimedia.org/w/index.php?curid=230543

Galileo’s observations were an enormous challenge to our understanding of ourselves at the time, and to the authorities at the time. He was forced to recant what he had seen, and he was put under house arrest. But he never really backed down from the observations he made with his 2 inch telescope. How could he?

Now, of course, there isn’t so much hostility towards people with telescopes. As time went on, larger and more powerful telescopes were built, and we’ve gotten used to our understanding going through tumultuous changes. We expect it, even anticipate it.

In our current times, Super Telescopes rule the day, and their sizes are measured in meters, not inches. And when new observations challenge our understanding of things, we cluster around out of curiosity, and try to work our way through it. We don’t condemn the results and order scientists to keep quiet.

The first of the Super Telescopes, as far as most of us are concerned, is the Hubble Space Telescope. From its perch in Low Earth Orbit (LEO), the Hubble has changed our understanding of the Universe on numerous fronts. With its cameras, and the steady stream of mesmerizing images those cameras deliver, a whole generation of people have been exposed to the beauty and mystery of the cosmos.

The Hubble Space Telescope could be considered the first of the Super Telescopes. In this image it is being released from the cargo bay of the Space Shuttle Discovery in 1990. Image: By NASA/IMAX - http://mix.msfc.nasa.gov/abstracts.php?p=1711, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6061254
The Hubble Space Telescope could be considered the first of the Super Telescopes. In this image it is being released from the cargo bay of the Space Shuttle Discovery in 1990. Image: By NASA/IMAX – http://mix.msfc.nasa.gov/abstracts.php?p=1711, Public Domain, https://commons.wikimedia.org/w/index.php?curid=6061254

Hubble has gazed at everything, from our close companion the Moon, all the way to galaxies billions of light years away. It’s spotted a comet breaking apart and crashing into Jupiter, dust storms on Mars, and regions of energetic star-birth in other galaxies. But Hubble’s time may be coming to an end soon, and other Super Telescopes are on the way.

Nowadays, Super Telescopes are expensive megaprojects, often involving several nations. They’re built to pursue specific lines of inquiry, such as:

  • What is the nature of Dark Matter and Dark Energy? How are they distributed in the Universe and what role do they play?
  • Are there other planets like Earth, and solar systems like ours? Are there other habitable worlds?
  • Are we alone or is there other life somewhere?
  • How do planets, solar systems, and galaxies form and evolve?

Some of the Super Telescopes will be on Earth, some will be in space. Some have enormous mirrors made up of individual, computer-controlled segments. The Thirty Meter Telescope has almost 500 of these segments, while the European Extremely Large Telescope has almost 800 of them. Following a different design, the Giant Magellan Telescope has only seven segments, but each one is over 8 meters in diameter, and each one weighs in at a whopping 20 tons of glass each.

This artistic bird's-eye view shows the dome of the ESO European Extremely Large Telescope (E-ELT) in all its glory, on top of the Chilean Cerro Armazones. The telescope is currently under construction and its first light is targeted for 2024.
This artistic bird’s-eye view shows the dome of the ESO European Extremely Large Telescope (E-ELT) in all its glory, on top of the Chilean Cerro Armazones. The telescope is currently under construction and its first light is targeted for 2024.

Some of the Super Telescopes see in UV or Infrared, while others can see in visible light. Some see in several spectrums. The most futuristic of them all, the Large Ultra-Violet, Optical, and Infrared Surveyor (LUVOIR), will be a massive space telescope situated a million-and-a-half kilometers away, with a 16 meter segmented mirror that dwarfs that of the Hubble, at a mere 2.4 meters.

Some of the Super Telescopes will discern the finest distant details, while another, the Large Synoptic Survey Telescope, will complete a ten-year survey of the entire available sky, repeatedly imaging the same area of sky over and over. The result will be a living, dynamic map of the sky showing change over time. That living map will be available to anyone with a computer and an internet connection.

A group photo of the team behind the Large Synoptic Survey Telescope. The group gathered to celebrate the casting of the 'scope's 27.5 ft diameter mirror. The LSST will create a living, detailed, dynamic map of the sky and make it available to anyone. Image: LSST Corporation
A group photo of the team behind the Large Synoptic Survey Telescope. The group gathered to celebrate the casting of the ‘scope’s 27.5 ft diameter mirror. The LSST will create a living, detailed, dynamic map of the sky and make it available to anyone. Image: LSST Corporation

We’re in for exciting times when it comes to our understanding of the cosmos. We’ll be able to watch planets forming around young stars, glimpse the earliest ages of the Universe, and peer into the atmospheres of distant exoplanets looking for signs of life. We may even finally crack the code of Dark Matter and Dark Energy, and understand their role in the Universe.

Along the way there will be surprises, of course. There always are, and it’s the unanticipated discoveries and observations that fuel our sense of intellectual adventure.

The Super Telescopes are technological masterpieces. They couldn’t be built without the level of technology we have now, and in fact, the development of Super Telescopes help drives our technology forward.

But they all have their roots in Galileo and his simple act of observing with a 2-inch telescope. That, and the curiosity about nature that inspired him.

The Rise of the Super Telescopes Series:

Rise of the Super Telescopes: The Large UV Optical Infrared Surveyor (LUVOIR) aka Hubble 2.0

An artist's illustration of a 16 meter segmented mirror space telescope. There are no actual images of LUVOIR because the design hasn't been finalized yet. Image: Northrop Grumman Aerospace Systems & NASA/STScI
An artist's illustration of a 16 meter segmented mirror space telescope. There are no actual images of LUVOIR because the design hasn't been finalized yet. Image: Northrop Grumman Aerospace Systems & NASA/STScI

We humans have an insatiable hunger to understand the Universe. As Carl Sagan said, “Understanding is Ecstasy.” But to understand the Universe, we need better and better ways to observe it. And that means one thing: big, huge, enormous telescopes.

In this series we’ll look at the world’s upcoming Super Telescopes:

The Large UV Optical Infrared Surveyor Telescope (LUVOIR)

There’s a whole generation of people who grew up with images from the Hubble Space Telescope. Not just in magazines, but on the internet, and on YouTube. But within another generation or two, the Hubble itself will seem quaint, and watershed events of our times, like the Moon Landing, will be just black and white relics of an impossibly distant time. The next generations will be fed a steady diet of images and discoveries stemming from the Super Telescopes. And the LUVOIR will be front and centre among those ‘scopes.

If you haven’t yet heard of LUVOIR, it’s understandable; LUVOIR is in the early stages of being defined and designed. But LUVOIR represents the next generation of space telescopes, and its power will dwarf that of its predecessor, the Hubble.

LUVOIR (its temporary name) will be a space telescope, and it will do its work at the LaGrange 2 point, the same place that JWST will be. L2 is a natural location for space telescopes. At the heart of LUVOIR will be a 15m segmented primary mirror, much larger than the Hubble’s mirror, which is a mere 2.4m in diameter. In fact, LUVOIR will be so large that the Hubble could drive right through the hole in the center of it.

This not-to-scale image of the Solar System shows the LaGrangian points. LUVOIR will be located in a halo orbit at L2, along with the JWST. Image: By Xander89 - File:Lagrange_points2.svg, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=36697081
This not-to-scale image of the Solar System shows the LaGrangian points. LUVOIR will be located in a halo orbit at L2, along with the JWST. Image: By Xander89 – File:Lagrange_points2.svg, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=36697081

While the James Webb Space Telescope will be in operation much sooner than LUVOIR, and will also do amazing work, it will observe primarily in the infrared. LUVOIR, as its name makes clear, will have a wider range of observation more like Hubble’s. It will see in the Ultra-Violet spectrum, the Optical spectrum, and the Infrared spectrum.

Recently, Brad Peterson spoke with Fraser Cain on a weekly Space Hangout, where he outlined the plans for the LUVOIR. Brad is a recently retired Professor of Astronomy at the Ohio State University, where served as chair of the Astronomy Department for 9 years. He is currently the chair of the Science Committee at NASA’s Advisory Council. Peterson is also a Distinguished Visiting Astronomer at the Space Telescope Science Institute, and the chair of the astronomy section of the American Association for the Advancement of Science.

Different designs for LUVOIR have been discussed, but as Peterson points out in the interview above, the plan seems to have settled on a 15m segmented mirror. A 15m mirror is larger than any optical light telescope we have on Earth, though the Thirty Meter Telescope and others will soon be larger.

“Segmented telescopes are the technology of today when it comes to ground-based telescopes. The JWST has taken that technology into space, and the LUVOIR will take segmented design one step further,” Peterson said. But the segmented design of LUVOIR differs from the JWST in several ways.

“…the LUVOIR will take segmented design one step further.” – Brad Peterson

JWST’s mirrors are made of beryllium and coated with gold. LUVOIR doesn’t require the same exotic design. But it has other requirements that will push the envelope of segmented telescope design. LUVOIR will have a huge array of CCD sensors that will require an enormous amount of electrical power to operate.

The Hubble Space Telescope on the left has a 2.4 meter mirror and the James Webb Space Telescope has a 6.5 meter mirror. LUVOIR, not shown, will dwarf them both with a massive 15 meter mirror. Image: NASA
The Hubble Space Telescope on the left has a 2.4 meter mirror and the James Webb Space Telescope has a 6.5 meter mirror. LUVOIR, not shown, will dwarf them both with a massive 15 meter mirror. Image: NASA

LUVOIR will not be cryogenically cooled like the JWST is, because it’s not primarily an Infrared observatory. LUVOIR will also be designed to be serviceable. In fact, the US Congress now requires all space telescopes to be serviceable.

“Congress has mandated that all future large space telescopes must be serviceable if practicable.” – Brad Peterson

LUVOIR is designed to have a long life. It’s multiple instruments will be replaceable, and the hope is that it will last in space for 50 years. Whether it will be serviced by robots, or by astronauts, has not been determined. It may even be designed so that it could be brought back from L2 for servicing.

LUVOIR will contribute to the search for life on other worlds. A key requirement for LUVOIR is that it do spectroscopy on the atmospheres of distant planets. If you can do spectroscopy, then you can determine habitability, and, potentially, even if a planet is inhabited. This is the first main technological challenge for LUVOIR. This spectroscopy requires a powerful coronagraph to suppress the light of the stars that exoplanets orbit. LUVOIR’s coronagraph will excel at this, with a ratio of starlight suppression of 10 billion to 1. With this capability, LUVOIR should be able to do spectroscopy on the atmospheres of small, terrestrial exoplanets, rather than just larger gas giants.

“This telescope is going to be remarkable. The key science that it’s going to do be able to do is spectroscopy of planets in the habitable zone around nearby stars.” – Brad Peterson

This video from NASA’s Goddard Space Flight Center talks about the search for life, and how telescopes like LUVOIR will contribute to the search. At the 15:00 mark, Dr. Aki Roberge talks about how spectroscopy is key to finding signs of life on exoplanets, and how LUVOIR will take that search one step further.

Using spectroscopy to search for signs of life on exoplanets is just one of LUVOIR’s science goals.

LUVOIR is tasked with other challenges as well, including:

  • Mapping the distribution of dark matter in the Universe.
  • Isolating the source of gravitational waves.
  • Imaging circumstellar disks to see how planets form.
  • Identifying the first starlight in the Universe, studying early galaxies and finding the first black holes.
  • Studying surface features of worlds in our Solar System.

To tackle all these challenges, LUVOIR will have to clear other technological hurdles. One of them is the requirement for long exposure times. This puts enormous constraints on the stability of the scope, since its mirror is so large. A system of active supports for the mirror segments will help with stability. This is a trait it shares with other terrestrial Super Telescopes like the Thirty Meter Telescope and the European Extremely Large Telescope. Each of those had hundreds of segments which have to be controlled precisely with computers.

A circumstellar disk of debris around a matured stellar system may indicate that Earth-like planets lie within. LUVOIR will be able to see inside the disk to watch planets forming.  Credit: NASA
A circumstellar disk of debris around a matured stellar system may indicate that Earth-like planets lie within. LUVOIR will be able to see inside the disk to watch planets forming.
Credit: NASA

LUVOIR’s construction, and how it will be placed in orbit are also significant considerations.

According to Peterson, LUVOIR could be launched on either of the heavy lift rockets being developed. The Falcon Heavy is being considered, as is the Space Launch System. The SLS Block 1B could do it, depending on the final size of LUVOIR.

“I’s going to require a heavy lift vehicle.” – Brad Peterson

Or, LUVOIR may never be launched into space. It could be assembled in space with pre-built components that are launched one at a time, just like the International Space Station. There are several advantages to that.

With assembly in space, the telescope doesn’t have to be built to withstand the tremendous force it takes to launch something into orbit. It also allows for testing when completed, before being sent to L2. Once the ‘scope was assembled and tested, a small ion propulsion engine could be used to power it to L2.

It’s possible that the infrastructure to construct LUVOIR in space will exist in a decade or two. NASA’s Deep Space Gateway in cis-lunar space is planned for the mid-20s. It would act as a staging point for deep-space missions, and for missions to the lunar surface.

LUVOIR is still in the early stages. The people behind it are designing it to meet as many of the science goals as they can, all within the technological constraints of our time. Planning has to start somewhere, and the plans presented by Brad Peterson represent the current thinking behind LUVOIR. But there’s still a lot of work to do.

“Typical time scale from selection to launch of a flagship mission is something like 20 years.” – Brad Peterson

As Peterson explains, LUVOIR will have to be chosen as NASA’s highest priority during the 2020 Decadal Survey. Once that occurs, then a couple more years are required to really flesh out the design of the mission. According to Peterson, “Typical time scale from selection to launch of a flagship mission is something like 20 years.” That gets us to a potential launch in the mid-2030s.

Along the way, LUVOIR will be given a more suitable name. James Webb, Hubble, Kepler and others have all had important missions named after them. Perhaps its Carl Sagan’s turn.

“The Carl Sagan Space Telescope” has a nice ring to it, doesn’t it?

A Single Wave, Bigger Than the Milky Way, is Rolling Through the Perseus Galaxy Cluster

NASA has discovered a wave of hot gas larger than the Milky Way rolling through the Perseus galaxy cluster. This X-ray image is the result of 16 days of observing with the Chandra X-ray Observatory. The image was filtered to make details easier to see.Credit: NASA's Goddard Space Flight Center/Stephen Walker et al.
NASA has discovered a wave of hot gas larger than the Milky Way rolling through the Perseus galaxy cluster. This X-ray image is the result of 16 days of observing with the Chandra X-ray Observatory. The image was filtered to make details easier to see.Credit: NASA's Goddard Space Flight Center/Stephen Walker et al.
NASA has discovered a wave of hot gas larger than the Milky Way  rolling through the Perseus galaxy cluster. This X-ray image is the result of 16 days of observing with the Chandra X-ray Observatory. The image was filtered to make details easier to see. Credits: NASA's Goddard Space Flight Center/Stephen Walker et al.
NASA has discovered a wave of hot gas larger than the Milky Way rolling through the Perseus galaxy cluster. This X-ray image is the result of 16 days of observing with the Chandra X-ray Observatory. The image was filtered to make details easier to see. Credits: NASA’s Goddard Space Flight Center/Stephen Walker et al.

An international team of scientists has discovered an enormous wave of hot gas rolling its way through the Perseus galaxy cluster. The wave is a giant version of what’s called a Kelvin-Helmholtz wave. They’re created when two fluids intersect at different velocities: for example, when wind blows over water.

In this instance, the wave was caused by a small galaxy cluster grazing the Perseus cluster, and setting off a chain of events lasting billions of years. The findings appear in a paper in the June 2017 issue of the journal Monthly Notices of the Royal Astronomical Society.

“The wave we’ve identified is associated with the flyby of a smaller cluster, which shows that the merger activity that produced these giant structures is still ongoing.” – Stephen Walker, NASA’s Goddard Space Flight Center.

“Perseus is one of the most massive nearby clusters and the brightest one in X-rays, so Chandra data provide us with unparalleled detail,” said lead scientist Stephen Walker at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “The wave we’ve identified is associated with the flyby of a smaller cluster, which shows that the merger activity that produced these giant structures is still ongoing.”

The Perseus galaxy cluster, also known as Abell 426, is 240 million light years away, and is about 11 million light years across. It’s one of the most massive objects we know of, and it’s named after the Perseus constellation, which appears in the same part of the sky.

Galaxy clusters are the largest gravitationally-bound objects in the Universe. Most of the observable matter in galaxy clusters is gas. But the gas is super hot—tens of millions of degrees hot—which means it emits x-rays.

X-Ray observations of Perseus have revealed several features and structures in the gas structure of the cluster. Some of them are bubble-like features caused by the super-massive black hole (SMBH) in NGC 1275, the Perseus cluster’s central galaxy. Another of these features is known as “the bay.” The bay is a concave feature which couldn’t have been formed by the SMBH.

This Hubble image shows NGC 1275, the Super-Massive Black Hole at the center of the Perseus cluster. NGC 1275 could not have been responsible for the "bay" feature found in Perseus. Image: By NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration - http://hubblesite.org/newscenter/archive/releases/2008/28/image/a/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4634173
This Hubble image shows NGC 1275, the Super-Massive Black Hole at the center of the Perseus cluster. NGC 1275 could not have been responsible for the “bay” feature found in Perseus. Image: By NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration – http://hubblesite.org/newscenter/archive/releases/2008/28/image/a/, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4634173

The bay is a puzzle because it doesn’t produce any emissions, which would be expected of something formed by a SMBH. The bay also doesn’t conform to models of how gas should behave in this situation.

The lead scientist behind the study is Stephen Walker at NASA’s Goddard Space Flight Center. Walker turned to the Chandra X-ray Observatory to help solve this puzzle. Existing Chandra images of the Perseus cluster were filtered in order to highlight the edges of structures, and to make any subtle details more visible.

These filtered and processed images were then compared to computer simulations of galaxy clusters merging. John ZuHone, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, has created an online catalog of these simulations.

“Galaxy cluster mergers represent the latest stage of structure formation in the cosmos.” -John ZuHone, Harvard-Smithsonian Center for Astrophysics.

“Galaxy cluster mergers represent the latest stage of structure formation in the cosmos. Hydrodynamic simulations of merging clusters allow us to produce features in the hot gas and tune physical parameters, such as the magnetic field. Then we can attempt to match the detailed characteristics of the structures we observe in X-rays.” -John ZuHone, Harvard-Smithsonian Center for Astrophysics.

This alternate image of the Perseus galaxy cluster shows the wave at the 7 o'clock position. Image: NASA's Goddard Space Flight Center/Stephen Walker et al.
This alternate image of the Perseus galaxy cluster shows the wave at the 7 o’clock position. Image: NASA’s Goddard Space Flight Center/Stephen Walker et al.

One of the simulations matched what astronomers were seeing in Perseus. In it, a large cluster like Perseus had settled itself into two regions: a colder region of gas around 30 million degrees Celsius, and a hotter region of gas at almost 100 million degrees Celsius. In this model, a cluster smaller than Perseus, but about a thousand times more massive than the Milky Way passes close to Perseus, missing its center by about 650,000 light years.

That happened about 2.5 billion years ago, and it set off a chain of events still playing itself out.

The near miss caused a gravitational disturbance that created an expanding spiral of the colder gas. An enormous wave of gas has formed at the edge of the spiral of colder gas, where it intersects with the hotter gas. This is the Kelvin-Helmholtz wave seen in the images.

“We think the bay feature we see in Perseus is part of a Kelvin-Helmholtz wave, perhaps the largest one yet identified, that formed in much the same way as the simulation shows,” Walker said. “We have also identified similar features in two other galaxy clusters, Centaurus and Abell 1795.”

The study provided another benefit besides just spotting an impossibly enormous wave. It allowed the team to measure the magnetic properties of the Perseus cluster. The researchers discovered that the strength of the magnetic field in the cluster affected the size of the wave of gas. It the field is too strong, the waves don’t form at all, and if the magnetic field is too weak, then the waves would be even larger.

According to the team, there is no other known way to measure the magnetic field.

Source: Scientists Find Giant Wave Rolling Through the Perseus Galaxy Cluster

Enjoy The Biggest Infrared Image Ever Taken Of The Small Magellanic Cloud Without All That Pesky Dust In The Way

The Small Magellanic Cloud is one of the highlights of the southern sky. It can be seen with the naked eye. But it is obscured by clouds of interstellar gas and dust, which makes it hard for optical telescopes to get a good look at it. This image, taken with the ESO's VISTA. is the biggest-ever image of the SMC, and shows millions of stars. Credit: ESO/VISTA VMC
The Small Magellanic Cloud is one of the highlights of the southern sky. It can be seen with the naked eye. But it is obscured by clouds of interstellar gas and dust, which makes it hard for optical telescopes to get a good look at it. This image, taken with the ESO's VISTA. is the biggest-ever image of the SMC, and shows millions of stars. Credit: ESO/VISTA VMC

The Small Magellanic Cloud (SMC) galaxy. Credit: ESA/VISTA
The Small Magellanic Cloud (SMC) galaxy. Credit: ESA/VISTA

The Small Magellanic Cloud (SMC) is one of the Milky Way’s nearest companions (along with the Large Magellanic Cloud.) It’s visible with the naked eye in the southern hemisphere. A new image from the European Southern Observatory’s (ESO) Visible and Infrared Survey Telescope for Astronomy (VISTA) has peered through the clouds that obscure it and given us our biggest image ever of the dwarf galaxy.

The SMC contains several hundred million stars, is about 7,000 light years in diameter, and is about 200,000 light years away. It’s one of the most distant objects that we can see with the naked eye, and can only be seen from the southern hemisphere (and the lowest latitudes of the northern hemisphere.)

The Small Magellanic Cloud is located in the Tucana constellation (The Toucan) in the southern hemisphere. The SMC is shown in green outline around the word 'Tucana'. Also shown are NGC 104 and NGC 362, unrelated objects that are much closer to Earth. Image: ESO, IAU and Sky & Telescope
The Small Magellanic Cloud is located in the Tucana constellation (The Toucan) in the southern hemisphere. The SMC is shown in green outline around the word ‘Tucana’. Also shown are NGC 104 and NGC 362, unrelated objects that are much closer to Earth. Image: ESO, IAU and Sky & Telescope

The SMC is a great target for studying how stars form because it’s so close to Earth, relatively speaking. But the problem is, its detail is obscured by clouds of interstellar gas and dust. So an optical survey of the Cloud is difficult.

But the ESO’s VISTA instrument is ideal for the task. VISTA is a near-infrared telescope, and infrared light is not blocked by the dust. VISTA was built at the ESO’s Paranal Observatory, in the Atacama Desert in Chile where it enjoys fantastic observing conditions. VISTA was designed to perform several surveys, including the Vista Magellanic Survey.

Explore the Zoomable image of the Small Magellanic Cloud. (You won’t be disappointed.)

The VISTA Magellanic Survey is focused on 3 main objectives:

  • The study of stellar populations in the Magellanic Clouds
  • The history of star formation in the Magellanic Clouds
  • The three-dimensional structure of the Magellanic Clouds

An international team led by Stefano Rubele of the University of Padova has studied this image, and their work has produced some surprising results. VISTA has shown us that most of the stars in this image are much younger than stars in other neighbouring galaxies. It’s also shown us that the SMC’s morphology is that of a warped disc. These are only early results, and there’s much more work to be done analyzing the VISTA image.

VISTA inside its enclosure at Paranal. VISTA has a 4.1 meter mirror, and its job is to survey large sections of the sky at once. In the background is the ESO's Very Large Telescope. Image: G. Hüdepohl
VISTA inside its enclosure at Paranal. VISTA has a 4.1 meter mirror, and its job is to survey large sections of the sky at once. In the background is the ESO’s Very Large Telescope. Image: G. Hüdepohl (atacamaphoto.com)/ESO

The team presented their research in a paper titled “The VMC survey – XIV. First results on the look-back time star formation rate tomography of the Small Magellanic Cloud“, published in the journal Monthly Notices of the Royal Astronomical Society.

As the authors say in their paper, the SMC is a great target for study because of its “rich population of star clusters, associations, stellar pulsators, primary distance indicators, and stars in shortlived evolutionary stages.” In a way, we’re fortunate to have the SMC so close. But studying the SMC was difficult, until the VISTA came online with its infrared capabilities.

VISTA saw first light on December 11th, 2009. It’s time is devoted to systematic surveys of the sky. In its first five years, it has undertaken large surveys of the entire southern sky, and also studied small patches of the sky to discern extremely faint objects. The leading image in this article is from the Vista Magellanic Survey, a survey covering 184 square degrees of the sky, taking in both the Small Magellanic Cloud and the Large Magellanic Cloud, and their environment.

Source: VISTA Peeks Through the Small Magellanic Cloud’s Dusty Veil