Elon Musk on stage at his September 27th presentation at the IAC. Image: SpaceX
When Elon Musk speaks publicly about SpaceX and their efforts to make space travel less expensive, people listen. He attracts all kinds of scientists and journalists to his presentations. But he also attracts… other types of people. And those people ask some strange questions.
Musk must be getting used to it by now. He’s one of those public figures that, by virtue of his efforts to bring the future closer, attracts a lot of interest. But some of the questions in the Q&A following his presentation on Sept. 27 were truly bizarre.
Anybody could stand in line at one of the microphones in the audience and ask their question. And ask they did.
One man started off by saying he just recently attended Burning Man in the desert. Mars is like one big desert, he said, with no water to wash away all the sewage. What will future Mars colonists do with all their s**t he asked?
I felt bad for the guy. Here was his chance to ask Musk, who is clearly some sort of hero the guy, any question about space travel. And he chose to ask about poop. It was truly cringe-worthy, but Musk handled it well. He must be used to it.
Elon Musk looking perplexed after being grilled about Martian toilets. Image: SpaceX
It’s not like it’s not a legitimate concern, way down the line, if we ever do establish a city. But good grief. Musk was there to talk about the Interplanetary Transport System, not the nuts and bolts of city planning. It’s clear that this gentleman travelled all that way just to ask about sewage. Fail. (Jump to 1:06:30 in the video for that bit of magic.)
Another person asked everyone to give Elon a hand because he “Inspires the s**t out of us!” (At 1:10:35 in the video.) Musk looked uncomfortable. I don’t think he likes the hero-worship part of his gig. The guy then tried to give him a comic book about Mars, but complained that security wouldn’t let him. Ummmm, yeah.
One person complained that SpaceX won’t hire internationally, and how can they claim to be going interplanetary when they won’t even hire from other countries? Musk patiently explained that when it comes to rocketry, the government tightly restricts who is allowed to come from other countries to work on projects. Rocketry is governed by the same rules as weaponry, as it turns out. Thanks for explaining, Elon.
There were others. One lady wanted to come upstairs and give him a kiss, on behalf of all the ladies. Another asked if they were going to mathematically determine the most expendable human on Earth, and send them to Mars? That gem is 1:16:45 in the video. BTW, that guy thought it would be Michael Cera. Huh?
The same guy wanted to pitch a comedy video to him after the presentation. He was, unfortunately, turned down.
Another guy, who called himself a “local idiot” asked if Elon himself was planning on going to Mars. The guy said he would’ve hated to put in all this work and then not go. Musk’s answer was, in short, that he would like to go, but only if a good succession plan was in place in case he perished. That way the company’s work could continue.
There were some good questions too, of course. Questions about launch site for the craft, where it will be manufactured, and other pertinent questions around who should be the first people to go. Others asked about the journey itself, and how travellers would be kept safe from radiation and other hazards. So the Q&A wasn’t a waste of time by any means.
The whole presentation is worth watching, if you haven’t already. For those of you who just want to watch the wackiest parts of the Q&A, you’re in luck. There’s a highlight video.
Apollo 11 moonwalker Buzz Aldrin discusses the human ‘Journey to Mars with Universe Today at newly opened ‘Destination Mars’ holographic experience during media preview at the Kennedy Space Center visitor complex in Florida on Sept. 18, 2016. Credit: Ken Kremer/kenkremer.com
Apollo 11 moonwalker Buzz Aldrin discusses the human ‘Journey to Mars with Universe Today at newly opened ‘Destination Mars’ holographic experience during media preview at the Kennedy Space Center visitor complex in Florida on Sept. 18, 2016. Credit: Ken Kremer/kenkremer.com
KENNEDY SPACE CENTER VISITOR COMPLEX, FL – Sending humans on a ‘Journey to Mars’ and developing strategies and hardware to accomplish the daunting task of getting ‘Humans to Mars’ is NASA’s agency wide goal and the goal of many space enthusiasts – including Apollo 11 moonwalker Buzz Aldrin.
NASA is going full speed ahead developing the SLS Heavy lift rocket and Orion crew module with a maiden uncrewed launch from the Kennedy Space Center set for late 2018 to the Moon. Crewed Mars missions would follow by the 2030s.
In the marketplace of ideas, there are other competing and corollary proposals as well from government, companies and private citizens on pathways to the Red Planet. For example SpaceX CEO Elon Musk wants to establish a colony on Mars using an Interplanetary Transport System of SpaceX developed rockets and spaceships.
Moonwalker Aldrin strongly advocated for more commercial activity in space and that “exposure to microgravity” for “many commercial products” is good, he told Universe Today.
More commercial activities in space would aid space commerce and getting humans to Mars.
“We need to do that,” Aldrin told me.
Apollo 11 moonwalker Buzz Aldrin describes newly opened ‘Destination Mars’ holographic experience during media preview at the Kennedy Space Center visitor complex in Florida on Sept. 18, 2016. Credit: Ken Kremer/kenkremer.com
Buzz Aldrin is the second man to set foot on the Moon. He stepped onto the lunar soil a few minutes after Apollo 11 Commander Neil Armstrong, on July 20, 1969 in the Sea of Tranquility.
Aldrin also strongly supports some type of American space station capability “beyond the ISS” to foster the Mars capability.
And we need to be thinking about that follow on “US capability” right now!
“I think we need to have a US capability beyond the ISS to prepare for future activities right from the beginning,” Aldrin elaborated.
Currently the ISS partnership of the US, Russia, ESA, Japan and Canada has approved extending the operations of the International Space Station (ISS) until 2024. What comes after that is truly not known.
NASA is not planning for a follow-on space station in low Earth orbit at this time. The agency seems to prefer development of a commercial space station, perhaps with core modules from Bigelow Aerospace and/or other companies.
So that commercial space station will have to be designed, developed and launched by private companies. NASA and others would then lease space for research and other commercial activities and assorted endeavors on the commercial space station.
For example, Bigelow wants to dock their privately developed B330 habitable module at the ISS by 2020, following launch on a ULA Atlas V. And then spin it off as an independent space station when the ISS program ends – see my story.
Only China has firm plans for a national space station in the 2020’s. And the Chinese government has invited other nations to submit proposals. Russia’s ever changing space exploration plans may include a space station – but that remains to be actually funded and seen.
Regarding Mars, Aldrin has lectured widely and written books about his concept for “cycling pathways to occupy Mars,” he explained.
Watch this video of Apollo 11 moonwalker Buzz Aldrin speaking to Universe Today:
Video Caption: Buzz Aldrin at ‘Destination Mars’ Grand Opening at KSCVC. Apollo 11 moonwalker Buzz Aldrin talks to Universe Today/Ken Kremer during Q&A at ‘Destination Mars’ Holographic Exhibit Grand Opening ceremony at Kennedy Space Center Visitor Complex (KSCVC) in Florida on 9/18/16. Credit: Ken Kremer/kenkremer.com
Here is a transcript:
Universe Today/Ken Kremer: Can you talk about the role of commercial space [in getting humans to Mars]. Elon Musk wants to try and send people to Mars, maybe even before NASA. What do you think?
Buzz Aldrin: “Well, being a transportation guy in space for humans – well commercial, what that brings to mind is tourism plus space travel.
And there are many many more things commercial that are done with products that can be fine tuned by exposure to microgravity. And we need to do that.”
“I think we need to have a US capability beyond the ISS to prepare for future activities right from the beginning.”
“And that’s why what has sort of fallen into place is the name for my plan for the future – which is ‘cycling pathways to occupy Mars.’”
“A cycler in low Earth orbit, one in lunar orbit, and one to take people to Mars.”
“And they are utilized in evolutionary fashion.”
Apollo 11 moonwalker Buzz Aldrin during media preview of newly opened ‘Destination Mars’ holographic experience at the Kennedy Space Center visitor complex in Florida on Sept. 18, 2016. Credit Julian Leek
Meanwhile, be sure to visit the absolutely spectacular “Destination Mars” holographic exhibit before it closes on New Year’s Day 2017 – because it is only showing at KSCVC.
A scene from ‘Destination Mars’ of Buzz Aldrin and NASA’s Curiosity Mars rover with the Gale crater rim in the distance. The new, limited time interactive exhibit is now showing at the Kennedy Space Center visitor complex in Florida through Jan 1, 2017. Credit: NASA/JPL/Microsoft
You can get more information or book a visit to Kennedy Space Center Visitor Complex, by clicking on the website link:
Apollo 11 moonwalker Buzz Aldrin discusses the human ‘Journey to Mars with Universe Today at newly opened ‘Destination Mars’ holographic experience during media preview at the Kennedy Space Center visitor complex in Florida on Sept. 18, 2016. Credit: Ken Kremer/kenkremer.com
When SpaceX CEO Elon Musk took to the stage at the International Astronautical Congress in Mexico on Monday, he announced his bold vision to send humanity into the Solar System, he laid out one of the most elaborate and ambitious projects ever put forward in the field of human space exploration.
Like many of you, I watched his announcement slack jawed at the implications.
My first thought? A spaceship capable of carrying 100 humans from Earth to Mars with a reusable main stage? Uh, that’s ambitious.
Scott Manley is one of my favorite YouTubers/Twitch Streamers. In case you’ve never seen him before, Scott is an absolute master of the space game, running instructional videos on EVE Online, Kerbal Space Program and other cosmic simulations.
Entering the atmosphere of Duna with 100 Kerbals on board.
The planets aligned, and Scott was planning to run a livestream game on his Twitch channel Monday night, so I jumped in and provided colour commentary while Scott constructed all aspects of the mission: a spacecraft capable of carrying 100 Kerbals safely to the surface of the Red Planet (Duna), a monster booster rocket to blast the crew compartment into orbit, and a refueling module that travels on a re-purposed booster.
Over the course of 2-hours, Scott built and tested all parts of the Interplanetary Transport Ship in KSP to varying levels of success. Some boosters exploded, Kerbals were left stranded on the surface of Duna (maybe that does match Musk’s plans), and Scott was unable to use the docking claw to mate spacecraft to transfer fuel.
In Scott’s defense, though, he was consuming 10% space beer during the broadcast.
But if I know Scott, he’s working on version 2 right now, and we’ll see a smooth video demonstrating all aspects of the mission shortly.
If you haven’t already, go ahead and subscribe to Scott’s channel, and enjoy the silliness.
P.S. If you’re interested in space games, Pamela and I discuss them in this week’s Astronomy Cast.
SpaceX's newly revealed Interplanetary Transit System will make travel to Mars, and other destinations in our Solar System, possible. Image: SpaceX
Today, Elon Musk elaborated on his plans to make humanity a planet-faring species. We’ve known for a long time that Mars is SpaceX’s destination, but the fine details haven’t been revealed. In today’s talk at the International Astronautical Congress (IAC), Musk revealed a game-changer for travel to Mars, and beyond.
If anyone has ever guessed that Musk’s plans involved a refuelling ship, I’ve never heard them say it out loud. But that’s exactly what Musk revealed. SpaceX plans to launch a Mars-bound craft into orbit, then launch a refuelling craft to refill the interplanetary ship’s fuel tanks. Only then would the Interplanetary Transport System (ITS) depart for Mars.
SpaceX’s proposed system is all about lowering the cost of travel to Mars. Only when the cost is lowered, does a sustained presence there become realistic. And Musk’s ITS system will definitely lower the cost.
Traditional space travel would cost $10 billion to get one person to Mars. Musk said that they can get it down to the median cost of a house in the US, about $200,000 US. The idea is that anyone who really wanted to could save up enough money and go to Mars. Musk did acknowledge that it will be tricky to reduce the cost of the Earth to Mars trip by a whopping 5 million percent.
There are four keys to reducing the cost:
full reusability
refilling in orbit
propellant production on Mars
right propellant
The ITS would feature reusable boosters, reusable spaceships, and refuelling in orbit. The interplanetary ship would be launched into orbit around Earth and parked there. Fuel ships would make 3 to 5 trips to fill the tank of the interplanetary ship waiting in orbit. From there, Musk thinks that the trip to Mars could take as little as 80 days. In the more distant future, that could be cut to 30 days.
The ITS requires an extraordinarily powerful booster, featuring 42 of SpaceX’s Raptor engines. Image: SpaceX
If this whole system isn’t shocking enough, and thrilling enough, for you, Musk has more than just one of these craft in mind. He imagines a fleet of them, perhaps 1,000, travelling en masse back and forth to Mars.
The ITS and its vital statistics. Image: SpaceX
The driving force behind all this is, of course, making Mars possible. In his presentation, Musk said we have two paths. One is to stay on Earth and face extinction from some doomsday event. The other is to become an interplanetary species, and use Mars to back up Earth’s biosphere. The SpaceX system is designed to make the second path possible.
Musk talked about the need to create a self-sustaining city in its own right. That obviously won’t happen right away, but it’ll never happen unless transport to Mars, and back, becomes feasible. With the proposed SpaceX system, Mars will be an option. Musk thinks that the ITS could also get us to one of the Jovian moons, if we could create fuel production and depots. In fact, he said we can probably go all the way to Pluto and beyond.
The ITS requires huge fuel tanks, one of which is seen here at SpaceX’s production facility. Image: SpaceX
There are a lot of challenges for this system. It’s far from a done deal. The system will require newer, more powerful engines. But SpaceX is already working on that. It’s called the Raptor, and testing has already begun.
Musk talked about the impressive exploration done on Mars by NASA and other agencies, but stressed that it’s time to take things further and aim for a sustained presence on Mars. To that end, SpaceX plans on sending a craft to Mars during every Earth-Mars opposition, which happens about every 2 years. Initially, that will be done with an unmanned Dragon capsule.
The mood at Musk’s presentation was one of excitement. The crowd was definitely there to see him. There was one humorous moment when Musk remarked “Timelines. I’m not the best at this sort of thing.” This is a nod to the difficulties with creating a timeline for something like the ITS. But really, what agency can adhere to strict schedules when doing something that’s never been done before? Especially in the realm of interplanetary travel?
The excitement surrounding Musk’s plans for travel to Mars is palpable. That’s understandable, considering the magnitude of what he’s talking about, and considering how long people have dreamed of going to Mars. The fact that someone with a track record like SpaceX’s is starting to lay the groundwork for travel to, and a presence on Mars, is exciting. There’s no way around it.
But there are lots of questions. Musk is the first to admit that he doesn’t have all the answers. He says up front that he sees his role as developing the transport system. Once that is moving ahead, others will address the challenges of establishing a presence on Mars.
One of the primary questions is around energy, and there are two sides to that. Fuel processing will have to be established quickly on Mars if the ships are to return to Earth.
This slide from Musk’s presentation show some of the considerations around producing fuel on Mars. Image: SpaceX
Musk also talked about the three possible fuel types to be derived on Mars.
This slide from Musk’s presentation shows the availability/desirability of the three types of fuel that could be derived from Mars. Image: SpaceX
The ITS ships will be able to carry a large payload, so it’s possible that the parts and pieces for a fuel plant could be pre-built somehow, then sent to Mars. There is an enormous amount of detail missing when it comes right down to it, but human ingenuity being what it is, this may be solvable.
Assuming that a rocket fuel plant could be assembled on Mars, that begs the second energy question. Creating this fuel will in itself require lots of energy. Much more than solar can provide. Musk briefly mentioned the possibility of nuclear energy, but didn’t go into detail. That’s understandable, because he clearly sees his role as developing the transportation system.
Establishing nuclear energy on Mars would also require a lot of infrastructure. On Earth, uranium processing is an enormous task. How will that be done on Mars? Is there enough uranium in Mars’ crust? Conventional atomic reactors use water, lots of it, to produce energy. Where will that water come from on Mars? Will the same amount be needed?
Or will thorium reactors be used? If you’re not up on thorium reactors, they are different than uranium reactors and are worth reading about. They use thorium for fuel, not uranium, and are different in other ways. They’re safer and produce less waste, but is there sufficient thorium available on Mars? Thorium is much more plentiful in Earth’s crust than uranium.
Small Modular Reactors (SMRs) are being developed for use on Earth. They are built in one location, then moved to their operational location. They can be linked together and require less sophisticated operators. Perhaps SMRs using thorium will provide the energy required for the ITS to work.
These questions are all important of course, and they bear thinking about. But one thing that can’t be denied is Musk’s vision. Anyone that wants humanity to survive, or that grew up reading science fiction, will love what Musk is doing. For that matter, anyone with a sense of adventure will love Musk.
Musk’s overall vision of us as a planet-faring species is something that will be a long time coming, I think. Fleets of interplanetary cargo ships plying the solar system, with fuelling depots along the way. An established human presence on Mars, the Moon, and perhaps the moons of the gas giants, and all the way out to Pluto.
It seems like a fanciful dream, but remember what Musk said at the start of his presentation. There are really only two paths. The first is to restrict ourselves to Earth, and die at the hands of some sort of extinction event.
The second path is to head outward and expand throughout the solar system.
It’s not science fiction anymore. It’s simple survival.
New research suggests that Mercury is still contracting and shrinking. Credits: NASA/JHUAPL/Carnegie Institution of Washington/USGS/Arizona State University
Mercury is a fascinating planet. As our Suns’ closest orbiting body, it experiences extremes of heat and cold, has the most eccentric orbit of any Solar planet, and an orbital resonance that makes a single day last as long as two years. But since the arrival of the MESSENGER probe, we have learned some new and interesting things about the planet’s geological history as well.
For example, images that were recently obtained by the NASA spacecraft revealed previously undetected landforms – small fault scarps – that appear to be geologically young. The presence of these features have led scientists to conclude that Mercury is still contracting over time, which means that – like Earth – it is tectonically active.
In geology, fault scarps refer to small step-like formations in the surface of a planet, where one side of a fault has moved vertically relative to the other. Previously, scientists believed that Mercury was tectonically dead, and that all major geological activity had taken place in the planet’s early history.
Images showing small fault scarps and trough (lower and upper white arrows) found on Mercury;s surface. Credits: NASA/JHUAPL/Carnegie Institution of Washington/Smithsonian Institution
This was evidenced by features spotted by the MESSENGER and Mariner 10 probes, both of which found evidence of large wrinkle ridges and fault scarps on the surface. The features were reasoned to be the result of Mercury contacting as it cooled early in its history (i.e. billion of years ago).
This action caused the planet’s crust to break, forming cliffs up to a kilometer and a half (about 1 mile) in height and hundreds of kilometers long. However, as the MESSENGER team noted, these small scarps were considerably younger, dating to about 50 million years of age.
They concluded that the scarps would have to be this young in order to survive bombardment by comets and meteoroids, a common occurrence on Mercury. They also noted their resemblance to similar features on the Moon, which also has young scarps that are the result of recent contraction.
“The young age of the small scarps means that Mercury joins Earth as a tectonically active planet, with new faults likely forming today as Mercury’s interior continues to cool and the planet contracts.”
The findings were made during the last 18 months of the MESSENGER mission, during which time the probe lowered its altitude to get higher-resolution images of the planet’s surface. The findings are also consistent with recent findings about Mercury’s global magnetic field, which appears to be powered by the planet’s slowly-cooling outer core.
As Jim Green, NASA’s Planetary Science Director, said of the discovery:
“This is why we explore. For years, scientists believed that Mercury’s tectonic activity was in the distant past. It’s exciting to consider that this small planet – not much larger than Earth’s moon – is active even today.”
All told, these findings have let scientists know that the planet is still alive, in the geological sense. It also means that that there is likely such as thing as Mercury-quakes, something which NASA is sure to follow up on if and when a lander mission (equipped with seismology instruments) is dispatched to the surface of the planet.
Canadians don’t have much to be proud of, but we can regale you with our ability to withstand freezing cold temperatures. Now, I live on the West Coast, so I’m soft and weak, rarely experiencing temperatures below freezing.
But for some of my Canadian brethren, temperatures can dip down to levels your mind and body can scarcely comprehend. For example, I have a friend who lives in Winnipeg, Manitoba. For a day last winter, the temperatures there dipped down -31C, but with the windchill, it felt like -50C. On that same day, it was a balmy -29C on Mars. On Mars!
But for scientists, and the Universe, it can get much much colder. So cold, in fact, that they use a completely different temperature scale – Kelvin – to measure how far away things are from the coldest possible temperature: Absolute Zero.
Nowhere close to absolute zero. Credit: Osccarr (CC BY 2.0)
On the Celsius scale, Absolute Zero is -273.15 degrees. And in Fahrenheit, it’s -459.67 degrees. In the Kelvin scale, however, it’s very simple. Absolute Zero is 0 kelvin.
At this point, a science explainer is going to stumble into a minefield of incorrect usage. It’s not 0 degrees kelvin, you don’t say the degrees part, just the kelvin part. Just kelvin.
This is because when you measure something from an arbitrary point, like the direction you just turned, you’ve changed course 15-degrees. But if you’re measuring from an absolute point, like the lowest physical temperature defined by nature, you drop the degrees because it’s an absolute. An Absolute Zero.
Of course, I’ve probably gotten that wrong too. This stuff is hard.
Anyway, back to Absolute Zero.
Still not cold enough. Credit: Lori Cuthbert (CC BY 2.0)
Absolute Zero is the coldest possible temperature that can theoretically be reached. At this point, no heat energy can be extracted from a system, no work can be done. It’s dead Jim.
But it’s completely theoretical. It’s practically impossible to cool something down to Absolute Zero. In order to cool something down, you need to do work to extract heat from it. The colder you get, the more work you need to do. In order to get to Absolute Zero, you’d need to put in an infinite amount of work. And that’s ridiculous.
As you probably learned in physics or chemistry class, the temperature of a gas translates to the motion of the particles in the gas. As you cool a gas down, by extracting heat from it, the particles slow down.
You would think, then, that by cooling something down to Absolute Zero, all particle motion in that something would stop. But that’s not true.
From a quantum mechanics point of view, you can never know the position and momentum of particles at the same time. If the particles stopped, you’d know their momentum (zero) and their position… right there. The Universe and its laws of physics just can’t allow that to happen. Thank Heisenberg’s Uncertainty Principle.
Therefore, there’s always a little motion, even if you could get to Absolute Zero, which you can’t. But you can’t extract any more heat from it.
The physicist Robert Boyle was one of the first to consider the possibility that there was a lowest possible temperature, which he called the primum frigidum. In 1702, Guillaume Amontons created a thermometer that he calculated would bottom out at -240 C. Pretty close, actually.
But it was Lord Kelvin, who created this absolute scale in 1848, starting at -273 C, or 0 kelvin.
A photograph of Lord Kelvin.
By this measurement, even with its windchill, Winnipeg was a balmy 223 kelvin on that wintry day.
The surface of Pluto, on the other hand varies from a low of 33 kelvin to a high of 55 kelvin. That’s -240 C to -218 C.
The average background temperature across the entire Universe is just 2.7 kelvin. You won’t find many places that cold, unless you get out to the vast cosmic voids that separate galaxy clusters.
Over time, the background temperature of the Universe will continue to drop, but it’ll never actually reach Absolute Zero. Even in a Googol years, when the last supermassive black hole has finally evaporated, and there’s no usable heat left in the entire Universe.
In fact, astronomers call this bleak future the “heat death” of the Universe. It’s heat death, as in, the death of all heat. And happiness.
You might be surprised to know that the coldest temperature in the entire Universe is right here on Earth. Well, sometimes, anyway. And assuming the aliens haven’t got better technology than us, which they probably do.
At the time that I’m recording this video, physicists have used lasers to cool down Rubidium-87 gas to just 170 nanokelvin, a tiny fraction above Absolute Zero. In fact, they won a Nobel Prize for their work in discovering Bose-Einstein condensates.
NASA is actually working on a new experiment called the Cold Atom Lab that will send a version of this technology to the International Space Station, where it should be able to cool material down to 100 picokelvin. That’s cold.
The Cold Atom Lab is planned to launch in August 2017. Credit: NASA / JPL
Here are your takeaways. Absolute Zero is the coldest possible temperature than can ever be reached, the point at which no further heat energy can be extracted from a system. Never say degrees kelvin, you’ll cause so much wincing. The Universe can’t match our cold generating abilities… yet. Take that Universe.
I’d love to hear the coldest temperature you’ve ever personally experienced. For me, it was visiting Buffalo in December. That’s not right.
09 March 2016 - Total Solar Eclipse from Palu, Indonesia. Credit and copyright: Justin Ng.
Imagine if you will, that you are a human being living in prehistoric times. You look up at the sky and see the Sun slowly being blocked out, becoming a ominous black sphere that glows around the edges. Could you really be faulted for thinking that this was some sort of supernatural event, or that the end of the world was nigh?
Of course not. Which is why for thousands of years, human beings believed that solar eclipses were just that – a sign of death or a bad omen. But in fact, an eclipse is merely what happens when one stellar object passes in front of another and obscures it. In astronomy, this happens all the time; and between the Sun, the Moon, and the Earth, total eclipses have been witnessed countless times throughout history.
Definition:
The general term for when one body passes in front of another in a solar system is transit. This term accurately describes how, depending on your vantage point, stellar bodies pass in front of each other on a regular basis, thus causing the reflected light from that body to be temporarily obscured.
However, when we are talking about how the Moon can pass between the Earth and the Sun, and how the Earth can pass between the Sun and the Moon, we use the term eclipse. This is also known as a syzygy, an astronomical term derived from ancient Greek (meaning “yoked together”) that describes a straight-line configuration between three celestial bodies.
Total Solar Eclipse:
When the Moon passes between the Sun and the Earth, and the Moon fully occults (blocks) the Sun, it is known as the solar eclipse. The type of solar eclipse – total or partial – depends on the distance of the Moon from the Earth during the event.
During an eclipse of the Sun, only a thin path on the surface of the Earth is actually able to experience a total eclipse – which is called the path of totality. People on either side of that path see a partial eclipse, where the Sun is only partly obscured by the Moon, relative to those who are standing in the center and witnessing the maximum point of eclipse.
A total solar eclipse occurs when the Earth intersects the Moon’s umbra – i.e. the innermost and darkest part of its shadow. These are relatively brief events, generally lasting only a few minutes, and can only be viewed along a relatively narrow track (up to 250 km wide). The region where a partial eclipse can be observed is much larger.
Totality! The view of the last total solar eclipse to cross a U.S. state (Hawaii) back in 1991. Credit and copyright: A. Nartist (shot from Cabo San Lucas, Baja California).
During a solar eclipse, the Moon can sometimes perfectly cover the Sun because its size is nearly the same as the Sun’s when viewed from the Earth. This, of course, is an illusion brought on by the fact that the Moon is much closer to us than the Sun.
And since it is closer, it can block the light from the Sun and cast a shadow on the surface of the Earth. If you’re standing within that shadow, the Sun and the Moon appear to line up perfectly, so that the Moon is completely darkened.
After a solar eclipse reaches totality, the Moon will continue to move past the Sun, obscuring smaller and smaller portions of it and allowing more and more light to pass.
Total Lunar Eclipse:
A total eclipse of the Moon is a different story. In this situation, the entire Moon passes into the Earth’s shadow, darkening it fully. A partial lunar eclipse occurs when the shadow of the Earth doesn’t fully cover the Moon, so only part of the Moon is darkened.
The phases of a total lunar eclipse. Saturday’s eclipse will see the briefest totality in a century. Credit: Keith Burns / NASA
Unlike a solar eclipse, a lunar eclipse can be observed from nearly anywhere in an entire hemisphere. In other words, observers all across planet Earth can see this darkening and it appears the same to all. For this reason, total lunar eclipses are much more common and easier to observe from a given location. A lunar eclipse also lasts longer, taking several hours to complete, with totality itself usually averaging anywhere from about 30 minutes to over an hour.
There are three types of lunar eclipses. There’s a penumbral eclipse, when the Moon crosses only the Earth’s penumbra (the region in which only a portion of light is obscured); followed by a partial, when the Moon crosses partially into the Earth’s umbra (where the light is completely blocked).
Last, there is a total eclipse, when the Moon crosses entirely into the Earth’s umbra. A total lunar eclipse involves the Moon passing through all three phases, then gradually passing out of the Earth’s shadow and becoming bright again. Even during a total lunar eclipse, however, the Moon is not completely dark.
Sunlight is still refracted through the Earth’s atmosphere and enters the umbra to provide faint illumination. Similar to what happens during a sunset, the atmosphere scatters shorter wavelength light, causing it to take on a red hue. This is where the phrase ‘Blood Moon‘ comes from.
Since the Moon orbits the Earth, you would expect to see an eclipse of the Sun and the Moon once a lunar month. However, this does not happen simply because the Moon’s orbit isn’t lined up with the Sun. In fact, the Moon’s orbit is tilted by a few degrees – 1.543º between the angle of the ecliptic and the lunar equator, to be exact.
This means that three objects only have the opportunity to line up and cause an eclipse a few times a year. It’s possible for a total of 7 solar and lunar eclipses every year, but that only happens a few times every century.
Other Types of Eclipses:
The term eclipse is most often used to describe a conjunction between the Earth, Sun and Moon. However, it can also refer to such events beyond the Earth–Moon system. For example, a planet moving into the shadow of one of its moons, a moon passing into the shadow of its host planet, or a moon passing into the shadow of another moon.
Mosaic of Saturn seen in eclipse in September 2006. Earth is the bright dot just inside the F ring at upper left. (CICLOPS/NASA/JPL-Caltech/SSI)
For instance, during the Apollo 12 mission in 1969, the crew was able to observe the Sun being eclipsed by the Earth. In 2006, during its mission to study Saturn, the Cassini spacecraft was able to capture the image above, which shows the gas giant transiting between the probe and the Sun.
In July of 2015, when the New Horizons mission passed through the shadow of Pluto, it was able to capture a stunning image of the dwarf planet eclipsing the Sun. The image was taken at a distance of about 2 million km (1.25 million miles), which provided the necessary vantage point to see the disc of the Sun become fully obscured.
On top of that, many other bodies in the Solar System can experience eclipses as well. These include the four gas giants, all of which have major moons that periodically transit between the planet and either Earth-based or space-based observatories.
The most impressive and common of these involve Jupiter and its four largest moons (Io, Europa, Ganymede and Callisto). Given the size and low axial tilt of these moons, they often experience eclipses with Jupiter as a result of transits, relative to our instruments.
An enviable view, of the most distant eclipse seen yet, as New Horizons flies through the shadow of Pluto. Credit: NASA/JPL.
A well-known example occurred in April of 2014, when the Hubble Space Telescope caught an image of Ganymede passing in front at of Jupiter. At the time the image was taken, Ganymede was casting its shadow within Jupiter’s Great Red Spot, which lent the planet a cyclops-like appearance (see below).
The other three gas giants are known to experiences eclipses as well. However, these only occur at certain periods the planet’s orbit of the Sun, due to their higher inclination between the orbits of their moons and the orbital plane of the planets. For instance, Saturn’s largest moon Titan has been known to only occult the ringed gas giant once about every 15 years.
Pluto has also been known to experience eclipses with is largest moon (and co-orbiting body) Charon. However, in all of these cases, the eclipses are never total, as they do not have the size to obscure the much larger gas giant. Instead, the passage of the moons in front of the larger celestial bodies either cast small shadows on the cloud tops of the gas giants, or lead to an annular eclipse at most.
Similarly, on Mars, only partial solar eclipses are ever possible. This is because Phobos or Deimos are not large enough (or distant enough in their orbits) to cover the Sun’s disc, as seen from the surface of the planet. Phobos and Deimos have also been known to experience lunar eclipses as they slip into the shadow of Mars.
Jupiter’s Great Red Spot and Ganymede’s Shadow. Image Credit: NASA/ESA/A. Simon (Goddard Space Flight Center)
Martian eclipses have been photographed numerous times from both the surface and from orbit. For example, in 2010, the Spirit rover captured images of a Martian lunar eclipse as Phobos, the larger of the two martian moons, was photographed while slipping into the shadow of Mars.
Also, between Nov. 4 and Nov. 5, 2010, the Opportunity rover captured several images (later turned into movies) of a Martian sunset. In the course of imaging the Sun for a total of 17 minutes, Opportunity captured stills of the Sun experiencing a solar eclipse. And on September 13th, 2012 – during the 37th day of its mission (Sol 27) – the Curiosity rover captured an image of Phobos transiting the Sun.
As far as astronomical events go, total eclipses (Lunar and Solar) are not uncommon occurrences. If you ever want to witness a one, all you need to do is keep track of when one will be visible from your part of the world. Some good resources for this are NASA’s Eclipse Website and timeanddate.com.
Or, if you’re the really adventurous type, you can find out where on Earth the next path of totality is going to be, and then book a vacation to go there. Get to the right spot at the right time, and you should be getting the view of a lifetime!
We have written many articles about the eclipse for Universe Today. Here’s a list of articles about specific times when a total Lunar Eclipse took place, and here’s a list of Solar Eclipse articles. And be sure to check out this article and video of an Annular Eclipse.
Artist's impression of a water vapor plume on Europa. Credit: NASA/ESA/K. Retherford/SWRI
Last week, on Tuesday, September 20th, NASA announced that they had made some interesting findings about Jupiter’s icy moon Europa. These were based on images taken by the Hubble Space Telescope, the details of which would be released on the following week. Needless to say, since then, the scientific community and general public have been waiting with baited breath.
Earlier today (September 26th) NASA put an end to the waiting and announced the Hubble findings during a NASA Live conference. According to the NASA panel, which was made up of members of the research team, this latest Europa-observing mission revealed evidence of plumes of saline water emanating from Europa’s surface. If true, this would mean that the moon’s subsurface ocean would be more accessible than previously thought.
Using Hubble’s Space Telescope Imaging Spectrograph (STIS) instrument, the team conducted observations of Jupiter and Europa in the ultra-violet spectrum over the course of 15 months. During that time, Europa passed in front of Jupiter (occulted the gas giant) on 10 separate occasions.
And on three of these occasions, the team saw what appeared to be plumes of water erupting from the surface. These plumes were estimated to be reaching up to 200 km (125 miles) from the southern region of Europa before (presumably) raining back onto the surface, depositing water ice and material from the interior.
The purpose of the observation was to examine Europa’s possible extended atmosphere (aka. exosphere). The method the team employed was similar to the one used to detect atmospheres around extra-solar planets. As William Sparks of the Space Telescope Science Institute (STScI) in Baltimore (and the team leader), explained in a NASA press release:
“The atmosphere of an extrasolar planet blocks some of the starlight that is behind it. If there is a thin atmosphere around Europa, it has the potential to block some of the light of Jupiter, and we could see it as a silhouette. And so we were looking for absorption features around the limb of Europa as it transited the smooth face of Jupiter.”
When they looked at Europa using this same technique, they noted that small patches on the surface were dark, indicating the absorption of UV light. This corresponded to previous work done by Lorenz Roth (of the Southwest Research Institute) and his team of researchers in 2012. At this time, they detected evidence of water vapor coming from Europa’s southern polar region.
Europa transit illustration. Europa orbits Jupiter every 3 and a half days, and on every orbit it passes in front of Jupiter, raising the possibility of plumes being seen as silhouettes absorbing the background light of Jupiter. Credits: A. Field (STScI)
As they indicated in a paper detailing their results – titled “Transient Water Vapor at Europa’s South Pole” – Roth’s team also relied on UV observations made using the Hubble telescope. Noting a statistically coincident amount of hydrogen and oxygen emissions, they concluded that this was the result of ejected water vapor being broken apart by Jupiter’s radiation (a process known as radiolysis).
Though their methods differed, Sparks and his research team also found evidence of these apparent water plumes, and in the same place no less. Based on the latest information from STIS, most of the apparent plumes are located in the moon’s southern polar region while another appears to be located in the equatorial region.
“When we calculate in a completely different way the amount of material that would be needed to create these absorption features, it’s pretty similar to what Roth and his team found,” Sparks said. “The estimates for the mass are similar, the estimates for the height of the plumes are similar. The latitude of two of the plume candidates we see corresponds to their earlier work.”
Another interesting conclusion to come from this and the 2012 study is the likelihood that these water plumes are intermittent. Basically, Europa is tidally-locked world, which means the same side is always being presented to us when it transits Jupiter. This occus once every 3.5 days, thus giving astronomers and planetary scientists plenty of viewing opportunities.
This composite image shows suspected plumes of water vapor erupting at the 7 o’clock position off the limb of Jupiter’s moon Europa. The Hubble data were taken on January 26, 2014. Credit: Credits: NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center
But the fact that plumes have been observed at some points and not others would seem to indicate that they are periodic. In addition, Roth’s team attempted to spot one of the plume’s observed by Sparks and his colleagues a week after they reported it. However, they were unable to locate this supposed water source. As such, it would appear that the plumes, if they do exist, are short-lived.
These findings are immensely significant for two reasons. On the one hand, they are further evidence that a warm-water, saline ocean exists beneath Europa’s icy surface. On the other, they indicate that any future mission to Europa would be able to access this salt-water ocean with greater ease.
Ever since the Galileo spacecraft conducted a flyby of the Jovian moon, scientists have believed that an interior ocean is lying beneath Europa’s icy surface – one that has between two and three times as much water as all of Earth’s oceans combined. However, estimates of the ice’s thickness range from it being between 10 to 30 km (6–19 mi) thick – with a ductile “warm ice” layer that increases its total thickness to as much as 100 km (60 mi).
Knowing the water periodically reaches the surface through fissures in the ice would mean that any future mission (which would likely include a submarine) would not have to drill so deep. And considering that Europa’s interior ocean is considered to be one of our best bets for finding extra-terrestrial life, knowing that the ocean is accessible is certainly exciting news.
A comparison of 2014 transit and 2012 Europa aurora observations. Credits: NASA, ESA, W. Sparks (left image) L. Roth (right image)
And the news is certainly causing its fair share of excitement for the people who are currently developing NASA’s proposed Mission to Europa, which is scheduled to launch sometime in the 2020s. As Dr. Cynthia B. Phillips, a Staff Scientist and the Science Communications Lead for the Europa Project, told Universe Today via email:
“This new discovery, using Hubble Space Telescope data, is an intriguing data point that helps lend support to the idea that there are active plumes on Europa today. While not an absolute confirmation, the new Sparks et al. result, in combination with previous observations by Roth et al. (also using HST but with a different technique), is consistent with the presence of intermittent plumes ejecting water vapor from the Southern Hemisphere of Europa. Such observations are difficult to perform from Earth, however, even with Hubble, and thus these results remain inconclusive.
“Confirming the presence or absence of plumes on Europa, as well as investigating many other mysteries of this icy ocean world, will require a dedicated spacecraft in the Jupiter system. NASA currently plans to send a multiple-flyby spacecraft to Europa, which would make many close passes by Europa in the next decade. The spacecraft’s powerful suite of scientific instruments will be able to study Europa’s surface and subsurface in unprecedented detail, and if plumes do exist, it will be able to observe them directly and even potentially measure their composition. Until the Europa spacecraft is in place, however, Earth-based observations such as the new Hubble Space Telescope results will remain our best technique to observe Jupiter’s mysterious moon.”
Naturally, Sparks was clear that this latest information was not entirely conclusive. While he believes that the results were statistically significant, and that there were no indications of artifacts in the data, he also emphasized that observations conducted in the UV wavelength are tricky. Therefore, more evidence is needed before anything can be said definitively.
In the future, it is hoped that future observation will help to confirm the existence of water plumes, and how these could have helped create Europa’s “chaos terrain”. Future missions, like NASA’s James Webb Space Telescope (scheduled to launch in 2018) could help confirm plume activity by observing the moon in infrared wavelengths.
As Paul Hertz, the director of the Astrophysics Division at NASA Headquarters in Washington, said:
“Hubble’s unique capabilities enabled it to capture these plumes, once again demonstrating Hubble’s ability to make observations it was never designed to make. This observation opens up a world of possibilities, and we look forward to future missions — such as the James Webb Space Telescope — to follow up on this exciting discovery.”
Other team members include Britney Schmidt, an assistant professor at the School of Earth and Atmospheric Sciences at Georgia Institute of Technology in Atlanta; and Jennifer Wiseman, senior Hubble project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Their work will be published in the Sept. 29 issue of the Astrophysical Journal.
And be sure to enjoy this video by NASA about this exciting find:
A 2014 Orionid meteor. Image credit and copright: Sharin Ahmad (@Shahgazer).
The month of October is upon us this coming weekend, and with it, one of the better annual meteor showers is once again active: the Orionids.
In 2016, the Orionid meteors are expected to peak on October 22nd at 2:00 UT (10:00 PM U.S. Eastern Time on October 21st) , favoring Europe and Africa in the early morning hours. The shower is active for a one month period from October 2nd to November 2nd, and can vary with a Zenithal Hourly Rate (ZHR) of 10-70 meteors per hour. This year, the Orionids are expected to produce a maximum ideal ZHR of 15-25 meteors per hour. The radiant of the Orionids is located near right ascension 6 hours 24 minutes, declination 15 degrees north at the time of the peak. The radiant is in the constellation of Orion very near its juncture with Gemini and Taurus.
A gallery of Fall meteor shower radiants, including the October Orionids. Image credit: Stellarium
The Moon is at a 55% illuminated, waning gibbous phase at the peak of the Orionids, making 2016 an unfavorable year for this shower, though that shouldn’t stop you from trying. It’s true that the Moon is only 19 degrees east of the radiant in the adjacent constellation Gemini at its peak on the key morning of October 22, though it’ll move farther on through the last week of October.
In previous recent years, the Orionids produced a Zenithal Hourly Rate (ZHR) of 20 (2014) and a ZHR of 30 (2013).
The Orionid meteors strike the Earth at a moderately fast velocity of 66 km/s, and the shower tends to produce a relatively high ratio of fireballs with an r value of = 2.5. The source of the Orionids is none other than renowned comet 1/P Halley. Halley last paid the inner solar system a visit in early 1986, and will once again reach perihelion on July 28, 2061. Let’s see, by then I’ll be…
The orientation of the Earth’s shadow vs the zenith positions of the Sun, Moon and the radiant of the Orionid meteors at the expected during the peak of the shower on October 22nd. Image adapted from Orbitron.
Unlike most meteor showers, the Orionids display a very unpredictable maximum – many sources decline to put a precise date on the shower’s expected maximum at all. On some years, the Orionids barely top 10 per hour at their maximum, while on others they display a broad but defined peak. One 1982 study out of Czechoslovakia suggested a twin peak for this shower after looking at activity from 1944 to 1950. All good reasons to be vigilant for Orionids throughout the coming month of October.
And check out this brilliant meteor that lit up the skies over the southern UK this past weekend:
‘Tis the season for cometary dust particles to light up the night sky. Trace the path of a suspect meteor to the club of Orion, and you’ve likely sighted an Orionid meteor. But other showers showers are active in October, including:
The Draconids: Peaking around October 8th, these are debris shed by Comet 21P Giacobini-Zinner. The Draconids are prone to great outbursts, such as the 2011 and 2012 meteor storm, but are expected to yield a paltry ZHR of 10 in 2016.
The Taurids: Late October into early November is Taurid fireball season, peaking with a ZHR of 5 around October 10th (the Southern Taurids) and November 12th (the Northern Taurids).
The Camelopardalids: Another wildcard shower prone to periodic outbursts. 2016 is expected to be an off year for this shower, with a ZHR of 10 topping out on October 5.
And farther afield, we’ve got the Leonids (November 17th) the Geminids (December 14th) and the Ursids (December 22nd) to close out 2016.
A 2015 Orionid captured by a NASA All-Sky camera atop Mt. Lemmon, Arizona. Image credit: NASA.
Observing a meteor shower like the Orionids is as simple as finding a dark site with a clear horizon, laying back and watching via good old Mark-1 eyeball. Blocking that gibbous Moon behind a building or hill will also increase your chances of catching an Orionid. Expect rates to pick up toward dawn, as the Earth turns forward and plows headlong into the meteor stream.
You can make a count of what you see and report it to the International Meteor Organization which keeps regular tabs of meteor activity.
Photographing Orionids this year might be problematic, owing to the proximity of the bright Moon, though not impossible. Again, aiming at a wide quadrant of the sky opposite to the Moon might just nab a bright Orionid meteor in profile. We like to just set our camera’s intervalometer to take a sequence of 30” exposures of the sky, and let it do the work while we’re observing visually. Nearly every meteor we’ve caught photographically turned up in later review, a testament to the limits of visual observing.
Aurora borealis in Fairbanks, AK. on Monday night March 16. Credit: John Chumack
The Northern Lights have fascinated human beings for millennia. In fact, their existence has informed the mythology of many cultures, including the Inuit, Northern Cree, and ancient Norse. They were also a source of intense fascination for the ancient Greeks and Romans, and were seen as a sign from God by medieval Europeans.
Thanks to the birth of modern astronomy, we now know what causes both the Aurora Borealis and its southern sibling – Aurora Australis. Nevertheless, they remain the subject of intense fascination, scientific research, and are a major tourist draw. For those who live north of 60° latitude, this fantastic light show is also a regular occurrence.
Causes:
Aurora Borealis (and Australis) is caused by interactions between energetic particles from the Sun and the Earth’s magnetic field. The invisible field lines of Earth’s magnetoshere travel from the Earth’s northern magnetic pole to its southern magnetic pole. When charged particles reach the magnetic field, they are deflected, creating a “bow shock” (so-named because of its apparent shape) around Earth.
However, Earth’s magnetic field is weaker at the poles, and some particles are therefore able to enter the Earth’s atmosphere and collide with gas particles in these regions. These collisions emit light that we perceive as wavy and dancing, and are generally a pale, yellowish-green in color.
The variations in color are due to the type of gas particles that are colliding. The common yellowish-green is produced by oxygen molecules located about 100 km (60 miles) above the Earth, whereas high-altitude oxygen – at heights of up to 320 km (200 miles) – produce all-red auroras. Meanwhile, interactions between charged particles and nitrogen will produces blue or purplish-red auroras.
Variability:
The visibility of the northern (and southern) lights depends on a lot of factors, much like any other type of meteorological activity. Though they are generally visible in the far northern and southern regions of the globe, there have been instances in the past where the lights were visible as close to the equator as Mexico.
In places like Alaska, Norther Canada, Norway and Siberia, the northern lights are often seen every night of the week in the winter. Though they occur year-round, they are only visible when it is rather dark out. Hence why they are more discernible during the months where the nights are longer.
The magnetic field and electric currents in and around Earth generate complex forces, and also lead to the phenomena known as aurorae. Credit: ESA/ATG medialab
Because they depend on the solar wind, auroras are more plentiful during peak periods of activity in the Solar Cycle. This cycle takes places every 11 years, and is marked by the increase and decrease of sunspots on the sun’s surface. The greatest number of sunspots in any given solar cycle is designated as a “Solar Maximum“, whereas the lowest number is a “Solar Minimum.”
A Solar Maximum also accords with bright regions appearing in the Sun’s corona, which are rooted in the lower sunspots. Scientists track these active regions since they are often the origin of eruptions on the Sun, such as solar flares or coronal mass ejections.
The most recent solar minimum occurred in 2008. As of January 2010, the Sun’s surface began to increase in activity, which began with the release of a lower-intensity M-class flare. The Sun continued to get more active, culminating in a Solar Maximum by the summer of 2013.
Locations for Viewing:
The ideal places to view the Northern Lights are naturally located in geographical regions north of 60° latitude. These include northern Canada, Greenland, Iceland, Scandinavia, Alaska, and Northern Russia. Many organizations maintain websites dedicated to tracking optimal viewing conditions.
An image captured of the northern lights, which appear pale purple and red, though the primary color visible to the eye was green. Credit: Bob Kin
For instance, the Geophysical Institute of the University of Alaska Fairbanks maintains the Aurora Forecast. This site is regularly updated to let residents know when auroral activity is high, and how far south it will extend. Typically, residents who live in central or northern Alaska (from Fairbanks to Barrow) have a better chance than those living in the south (Anchorage to Juneau).
In Northern Canada, auroras are often spotted from the Yukon, the Northwest Territories, Nunavut, and Northern Quebec. However, they are sometimes seen from locations like Dawson Creek, BC; Fort McMurry, Alberta; northern Saskatchewan and the town of Moose Factory by James Bay, Ontario. For information, check out Canadian Geographic Magazine’s “Northern Lights Across Canada“.
The National Oceanic and Atmospheric Agency also provides 30 minute forecasts on auroras through their Space Weather Prediction Center. And then there’s Aurora Alert, an Android App that allows you to get regular updates on when and where an aurora will be visible in your region.
Understanding the scientific cause of auroras has not made them any less awe-inspiring or wondrous. Every year, countless people venture to locations where they can be seen. And for those serving aboard the ISS, they got the best seat in the house!
Speaking of which, be sure to check out this stunning NASA video which shows the Northern Lights being viewed from the ISS:
For more information, visit the THEMIS website – a NASA mission that is currently studying space weather in great detail. The Space Weather Center has information on the solar wind and how it causes aurorae.
