Special Guest:
Dr. Natalie Batalha is an astrophysicist at NASA Ames Research Center and project scientist for NASA’s Kepler Mission. Dr. Batalha leads the effort to understand planet populations in the galaxy based on Kepler’s discoveries, and in 2015 she joined the leadership team of NASA’s Nexus for Exoplanet System Science Coalition (NExSS,) a multidisciplinary team dedicated to searching for evidence of life beyond the Solar System as well as understanding the diversity of exoplanetary worlds and which of these worlds are most likely to harbor life.
We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!
Announcements:
The WSH recently welcomed back Mathew Anderson, author of “Our Cosmic Story,” to the show to discuss his recent update. He was kind enough to offer our viewers free electronic copies of his complete book as well as his standalone update. Complete information about how to get your copies will be available on the WSH webpage – just visit http://www.wsh-crew.net/cosmicstory for all the details.
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!
We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page
Special Guest:
Tim Blais is the founder of A Capella Science, an “educational and utterly nerdy online video project.” You can find his videos online on YouTube at A Capella Science.
We use a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!
Announcements:
On Friday, May 12, the WSH will welcome authors Michael Summers and James Trefil to the show to discuss their new book, Exoplanets: Diamond Worlds, Super Earths, Pulsar Planets and the New Search for Life Beyond Our Solar System. In anticipation of their appearance, the WSH Crew is pleased to offer our viewers a chance to win one of two hard cover copies of Exoplanets. Two winners will be drawn live by @fraser during our show on May 12th. To enter for a chance to win a copy of Exoplanets, send an email to: [email protected] with the Subject: Exoplanets. Be sure to include your name and email address in the body of your message so that we can contact the winners afterward. All entries must be electronically postmarked by 23:59 EST on May 10, 2017, in order to be eligible. No purchase necessary. Two winners will be selected at random from all eligible entries. Good luck!
If you’d like to join Fraser and Paul Matt Sutter on their Tour to Iceland in February 2018, you can find the information at astrotouring.com.
If you would like to join the Weekly Space Hangout Crew, visit their site here and sign up. They’re a great team who can help you join our online discussions!
We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Universe Today, or the Universe Today YouTube page<
A new study announced the discovery of a system hosting five transiting planets (image credit: jhmart1/deviantart).
A new study announced the discovery of a system hosting five transiting planets (image credit: jhmart1/deviantart).
NASA’s planet-discovering Kepler mission suffered a major mechanical failure in May 2013, but thanks to innovative techniques subsequently implemented by astronomers the satellite continues to uncover worlds beyond our Solar System (i.e., exoplanets). Indeed, Andrew Vanderburg (CfA) and colleagues just published results highlighting a new system found to host five transiting planets, which include: two sub-Neptune sized planets, a Neptune sized planet, a sub-Saturn sized planet, and a Jupiter sized planet.
Thanks to Ptolemy and his cronies, everyone used to think that the Earth was the center of the Solar System, with the Sun, planets and even the stars orbiting around it on a series of concentric crystal spheres. It was a clever idea, and explained the motions of the planets… sort of.
Then Copernicus figured out in 1543, that the Earth isn’t the centre of the Solar System. In fact, it’s just one planet in a vast Solar System, with objects whirling and whirling around the Sun.
With the structure of the Solar System figured out, and the crystal sphere idea in the garbage, astronomers still had a big unknown: how big is the Solar System?
Was it a few million kilometers across, or hundreds of millions. How big is the Sun? How far away is Venus?
Astronomers needed some kind of cosmic yardstick to measure everything against. Figure out one piece of the puzzle, and then you could measure everything else in relation.
In 1627, Johannes Kepler figured out that the motion of Venus was predictable, and that Venus would pass in front of the Sun in 1631, probably in the afternoon.
A timelapse of Mercury transiting across the face of the Sun. Credit: NASA
This is known as a “transit” of Venus.
The first crude measurements of Venus’ motion across the Sun were made in 1639 by Jeremiah Horrocks and William Crabtree from two different spots in England. And with these two observations, they were able to calculate the geometry between the Earth, Venus and the Sun.
If you recall all those memories you’re repressing from your high school geometry, once you’ve got an angle and a side of a triangle, you can work out all the other parts of the triangle. Horrocks and Crabtree worked out the distance from the Earth to the Sun within about 2/3rd accuracy. Not bad, considering the fact that astronomers literally had no idea before this point.
Following on from this observation, astronomers returned to their telescopes with each transit of Venus, better refining their calculations, and eventually settling on the current distance of about 150 million kilometers.
The 1882 transit of Venus.
From here on Earth, we can see a few objects pass in front of the Sun: Venus, Mercury and the Moon.
Venus transits are the most rare, happening two times every 108 years or so. Mercury transits happen more often, about a dozen times a century. And a transit of the Moon, also known as a solar eclipse, happens a few times a year, on average.
It’s all a matter of perspective. If you’re standing on the Moon, you might see the Earth pass in front of the Sun. We’d call that a lunar eclipse, while the lunatics would call it an Earth transit.
We can also see transits in other parts of the Solar System, like when moons pass in front of planets. For example, if you have a small telescope, you can see when Jupiter’s larger moons pass in front of the planet from our perspective.
One of the questions you might have, though, is why don’t these transits happen more often. Why don’t we see a Mercury or Venus transit every time they line up with us and the Sun.
This is because the planets aren’t exactly lined up at the same angle towards the Sun. All of the planets are inclined at an angle that takes them above or below the Sun at various points of their orbit.
For example, Venus’ orbit is inclined 3 degrees off the Sun’s equator, while the Earth is inclined 7 degrees. This means that most of the time that Venus and Earth are lined up, Venus is either above or below the Sun.
Are you an ageless vampire, or planning to live a long time in multiple robot bodies, then you’re in luck. In the year 69,163, there’ll be a double transit on the surface of Sun with both Mercury and Venus at the same time. Enjoy that while you contemplate the horror of your existence.
Once we become a true Solar System civilization, there will be even more opportunities for transits. People living on Mars will be able to see Mercury, Venus and even transits of Earth passing in front of the Sun. Neptunians will be bored they can see them so often.
The transit method is one of the ways that astronomers discover planets orbiting other stars. Using a space telescope like Kepler, they survey a portion of the night sky, watching the brightness of thousands of stars. When a planet perfectly passes directly in between us and a star, Kepler detects a drop in brightness.
Since its deployment in 2007, Kepler has confirmed the existence of over 2000 extra-solar planets. Credit: NASA
When you think of the geometries involved, it’s amazing this even happens at all. But the Universe is a vast place. Even if only a tiny percentage of star systems are perfectly lined up with us, there are enough to help us discover thousands and thousands of planets.
Kepler has turned up Earth-sized worlds orbiting other stars, some of which are even orbiting in their planet’s habitable zone.
Watching planetary transits is more than just a fun astronomy event, they’re how astronomers figured out the size of the Solar System itself. And now they help us find other planets orbiting other stars.
So, let’s agree to meet up in 2117 to catch the next transit of Venus, and celebrate this amazing event.
Special Guest:
Arne Christer Fuglesang is a Swedish physicist and an ESA astronaut. He was first launched aboard the STS-116 Space Shuttle mission on December 10, 2006, making him the first Swedish citizen in space.
We’ve had an abundance of news stories for the past few months, and not enough time to get to them all. So we’ve started a new system. Instead of adding all of the stories to the spreadsheet each week, we are now using a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!
We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Google+, Universe Today, or the Universe Today YouTube page.
An exoplanet seen from its moon (artist's impression). Via the IAU.
Is there life on other planets, somewhere in this enormous Universe? That’s probably the most compelling question we can ask. A lot of space science and space missions are pointed directly at that question.
The Kepler mission is designed to find exoplanets, which are planets orbiting other stars. More specifically, its aim is to find planets situated in the habitable zone around their star. And it’s done so. The Kepler mission has found 297 confirmed and candidate planets that are likely in the habitable zone of their star, and it’s only looked at a tiny patch of the sky.
But we don’t know if any of them harbour life, or if Mars ever did, or if anywhere ever did. We just don’t know. But since the question of life elsewhere in the Universe is so compelling, it’s driven people with intellectual curiosity to try and compute the likelihood of life on other planets.
One of the main ways people have tried to understand if life is prevalent in the Universe is through the Drake Equation, named after Dr. Frank Drake. He tried to come up with a way to compute the probability of the existence of other civilizations. The Drake Equation is a mainstay of the conversation around the existence of life in the Universe.
The Drake Equation is a way to calculate the probability of extraterrestrial civilizations in the Milky Way that were technologically advanced to communicate. When it was created in 1961, Drake himself explained that it was really just a way of starting a conversation about extraterrestrial civilizations, rather than a definitive calculation. Still, the equation is the starting point for a lot of conversations.
But the problem with the Drake equation, and with all of our attempts to understand the likelihood of life starting on other planets, is that we only have the Earth to go by. It seems like life on Earth started pretty early, and has been around for a long time. With that in mind, people have looked out into the Universe, estimated the number of planets in habitable zones, and concluded that life must be present, and even plentiful, in the Universe.
But we really only know two things: First, life on Earth began a few hundred million years after the planet was formed, when it was sufficiently cool and when there was liquid water. The second thing that we know is that a few billions of years after life started, creatures appeared which were sufficiently intelligent enough to wonder about life.
In 2012, two scientists published a paper which reminded us of this fact. David Spiegel, from Princeton University, and Edwin Turner, from the University of Tokyo, conducted what’s called a Bayesian analysis on how our understanding of the early emergence of life on Earth affects our understanding of the existence of life elsewhere.
A Bayesian analysis is a complicated matter for non-specialists, but in this paper it’s used to separate out the influence of data, and the influence of our prior beliefs, when estimating the probability of life on other worlds. What the two researchers concluded is that our prior beliefs about the existence of life elsewhere have a large effect on any probabilistic conclusions we make about life elsewhere. As the authors say in the paper, “Life arose on Earth sometime in the first few hundred million years after the young planet had cooled to the point that it could support water-based organisms on its surface. The early emergence of life on Earth has been taken as evidence that the probability of abiogenesis is high, if starting from young-Earth-like conditions.”
A key part of all this is that life may have had a head start on Earth. Since then, it’s taken about 3.5 billion years for creatures to evolve to the point where they can think about such things. So this is where we find ourselves; looking out into the Universe and searching and wondering. But it’s possible that life may take a lot longer to get going on other worlds. We just don’t know, but many of the guesses have assumed that abiogenesis on Earth is standard for other planets.
What it all boils down to, is that we only have one data point, which is life on Earth. And from that point, we have extrapolated outward, concluding hopefully that life is plentiful, and we will eventually find it. We’re certainly getting better at finding locations that should be suitable for life to arise.
What’s maddening about it all is that we just don’t know. We keep looking and searching, and developing technology to find habitable planets and identify bio-markers for life, but until we actually find life elsewhere, we still only have one data point: Earth. But Earth might be exceptional.
As Spiegel and Turner say in the conclusion of their paper, ” In short, if we should find evidence of life that arose wholly idependently of us – either via astronomical searches that reveal life on another planet or via geological and biological studies that find evidence of life on Earth with a different origin from us – we would have considerably stronger grounds to conclude that life is probably common in our galaxy.”
With our growing understanding of Mars, and with missions like the James Webb Space Telescope, we may one day soon have one more data point with which we can refine our probabilistic understanding of other life in the Universe.
Or, there could be a sadder outcome. Maybe life on Earth will perish before we ever find another living microbe on any other world.
Special Guest: Howard Trottier, a physics professor at Simon Fraser University (SFU) in British Columbia, Canada. Dr. Trottier has recently devoted his time to the development of SFU’s unique Astronomy public outreach program. In the heart of SFU’s main campus is a “”Science Courtyard,”” a high-profile public space devoted to astronomy and anchored by a state-of-the art outreach and teaching observatory. You can learn more about this amazing program here.
We’ve had an abundance of news stories for the past few months, and not enough time to get to them all. So we’ve started a new system. Instead of adding all of the stories to the spreadsheet each week, we are now using a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!
We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Google+, Universe Today, or the Universe Today YouTube page.
Visible, infrared, and X-ray light image of Kepler's supernova remnant (SN 1604) located about 13,000 light-years away. Credit: NASA, ESA, R. Sankrit and W. Blair (Johns Hopkins University).
We all know that we are “made of star-stuff,” with all of the elements necessary for the formation of planets and even life itself having originated inside generations of massive stars, which over billions of years have blasted their creations out into the galaxy at the explosive ends of their lives. Supernovas are some of the most powerful and energetic events in the known Universe, and when a dying star finally explodes you wouldn’t want to be anywhere nearby—fresh elements are nice and all but the energy and radiation from a supernova would roast any planets within tens if not hundreds of light-years in all directions. Luckily for us we’re not in an unsafe range of any supernovas in the foreseeable future, but there was a time geologically not very long ago that these stellar explosions are thought to have occurred in nearby space… and scientists have recently found the “smoking gun” evidence at the bottom of the ocean.
Two independent teams of “deep-sea astronomers”—one led by Dieter Breitschwerdt from the Berlin Institute of Technology and the other by Anton Wallner from the Australian National University—have investigated sediment samples taken from the floors of the Pacific, Atlantic, and Indian oceans. The sediments were found to contain relatively high levels of iron-60, an unstable isotope specifically created during supernovas.
The Local Bubble is a 300-light-year long region that was carved out of the interstellar medium by supernovas (Source: Science@NASA)
The teams found that the ages of the iron-60 concentrations (the determination of which was recently perfected by Wallner) centered around two time periods, 1.7 to 3.2 million years ago and 6.5 to 8.7 million years ago. Based on this and the fact that our Solar System currently resides within a peanut-shaped region virtually empty of interstellar gas known as the Local Bubble, the researchers are confident that this provides further evidence that supernovas exploded within a mere 330 light-years of Earth, sending their elemental fallout our way.
“This research essentially proves that certain events happened in the not-too-distant past,” said Adrian Melott, an astrophysicist and professor at the University of Kansas who was not directly involved with the research but published his take on the findings in a letter in Nature. (Source)
The researchers think that two supernova events in particular were responsible for nearly half of the iron-60 concentrations now observed. These are thought to have taken place among a a nearby group of stars known as the Scorpius–Centaurus Association, some 2.3 and 1.5 million years ago. At those same time frames Earth was entering a phase of repeated global glaciation, the end of the last of which led to the rise of modern human civilization.
While supernovas of those sizes and distances wouldn’t have been a direct danger to life here on Earth, could they have played a part in changing the climate?
“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.”
Regardless of the correlation, if any, between ice ages and supernovas, it’s important to learn how these events do affect Earth and realize that they may have played an important and perhaps overlooked role in the history of life on our planet.
“Over the past 500 million years there must have been supernovae very nearby with disastrous consequences,” said Melott. “There have been a lot of mass extinctions, but at this point we don’t have enough information to tease out the role of supernovae in them.”
You can find the teams’ papers in Nature here and here.
UPDATE 4/14/16: The presence of iron-60 from the same time periods as those mentioned above has also been found on the Moon by research teams in Germany and the U.S. Read more here.
Guests:This week, we welcome Andrew Helton and Ryan Hamilton, member of the SOFIA Telescope Team.
Andrew is the Instrument Scientist for the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST) dual channel, mid-infrared camera and spectrograph, one of the observatory’s facility-class science instruments.
Ryan is the Instrument Scientist for the upgraded High-resolution Airborne Wideband Camera (HAWC+) on board NASA’s Stratospheric Observatory for Infrared Astronomy (SOFIA).
We’ve had an abundance of news stories for the past few months, and not enough time to get to them all. So we’ve started a new system. Instead of adding all of the stories to the spreadsheet each week, we are now using a tool called Trello to submit and vote on stories we would like to see covered each week, and then Fraser will be selecting the stories from there. Here is the link to the Trello WSH page (http://bit.ly/WSHVote), which you can see without logging in. If you’d like to vote, just create a login and help us decide what to cover!
We record the Weekly Space Hangout every Friday at 12:00 pm Pacific / 3:00 pm Eastern. You can watch us live on Google+, Universe Today, or the Universe Today YouTube page.
“Life exists because of supernovae,” said Steve Howell, project scientist for NASA’s Kepler and K2 missions at NASA’s Ames Research Center. “All heavy elements in the universe come from supernova explosions. For example, all the silver, nickel, and copper in the earth and even in our bodies came from the explosive death throes of stars.”
So a glimpse of a supernova explosion is of intense interest to astronomers. It’s a chance to study the creation and dispersal of the life-enabling elements themselves. A greater understanding of supernovae will lead to a greater understanding of the origins of life.
Stars are balancing acts. They are a struggle between the pressure to expand, created by the fusion in the star, and the gravitational urge to collapse, caused by their own enormous mass. When the core of a star runs out of fuel, the star collapses in on itself. Then there is a massive explosion, which we call a supernova. And only very large stars can become supernovae.
The brilliant flashes that accompany supernovae are called shock breakouts. These events last only about 20 minutes, an infinitesimal amount of time for an object that can shine for billions of years. But when Kepler captured two of these events in 2011, it was more than just luck.
Peter Garnavich is an astrophysics professor at the University of Notre Dame. He led an international team that analyzed the light from 500 galaxies, captured every 30 minutes over a period of 3 years by Kepler. They searched about 50 trillion stars, trying to catch one as it died as a supernova. Only a fraction of stars are large enough to explode as supernovae, so the team had their work cut out for them.
“In order to see something that happens on timescales of minutes, like a shock breakout, you want to have a camera continuously monitoring the sky,” said Garnavich. “You don’t know when a supernova is going to go off, and Kepler’s vigilance allowed us to be a witness as the explosion began.”
An artist’s concept of a shock breakout. Image: NASA Ames/STScl/G. Bacon
In 2011 Kepler caught two gigantic stars as they died their supernova death. Called KSN 2011a, and KSN 2011d, the two red super-giants were 300 times and 500 times the size of our Sun respectively. 2011a was 700 million light years from Earth, and 2011d was 1.2 billion light years away.
The intriguing part of the two supernovae is the difference between them; one had a visible shock breakout and one did not. This was puzzling, since in other respects, both supernovae behaved much like theory predicted they would. The team thinks that the smaller of the two, KSN 2011a, may have been surrounded by enough gas to mask the shock breakout.
The Kepler spacecraft is well-known for searching for and discovering extrasolar planets. But when some components on board Kepler failed in 2013, the mission was re-cast as the K2 Mission. “While Kepler cracked the door open on observing the development of these spectacular events, K2 will push it wide open, observing dozens more supernovae,” said Tom Barclay, senior research scientist and director of the Kepler and K2 guest observer office at Ames. “These results are a tantalizing preamble to what’s to come from K2!”
(For a brilliant and detailed look at the life-cycle of stars, I recommend “The Life and Death of Stars” by Kenneth R. Lang.)
