Because I never get tired of time lapse videos taken from space, here is one created by Tomislav Safundžić called This Is Our Planet:
I like how it speeds the pace up over most such videos; at some spots there’s a frenetic feel to it that is counter to how I usually think of what it’s like to serenely orbit the Earth. I like the music, too! I’ve written about these time lapse videos many times, and described what’s in them, including the aurorae, the air glow, identifying cities from space, and so on.
See the Related Posts links below. As beautiful as these videos are, I find they are even more amazing when you actually understand what you’re seeing.
On board the International Space Station, ESA astronaut André Kuipers just put up this ridiculously cool and fun picture of himself playing with water in space:
Wheee! But what are you seeing?
Let me explain.
The really short version of this is that the water is acting like a lens, flipping his face over. But there are two images of André’s face in there, and one is upside down! What gives?
First we need to look a the drop itself. On Earth, sitting on a surface like a tabletop, water drops tend to be flattened. But in space, where gravity’s not an issue, water drops form little spheres. That’s because of surface tension, an imbalance in the electromagnetic forces between water molecules, and is a whole post all by itself! But for now, what you need to know is that in orbit where there’s no net effect from gravity, water droplets form little balls.
In this case, you can see the drop isn’t a perfect sphere; it’s big enough that it can oscillate like a spring, elongating in one direction. That’s cool, but doesn’t affect what’s going on here too much — it just elongates the image of his face seen in the drop a little bit.
But we’re not done! The astronauts injected an air bubble into the drop. On Earth, that bubble would rise and pop, but again, when gravity isn’t your master, the bubble stays put. So in the middle of the water drop is an evacuated sphere filled with air.
So what’s with the funhouse mirror stuff?
Ah, that’s because light can be bent! When a beam of light passes through water or some other transparent material, the direction it’s traveling changes, which is why a spoon sitting in a glass of water looks like someone bent it. This is called refraction, and depends on two different things: the material itself (different stuff bends light by different amounts) and the direction from which the light hits it.
The shape of the refracting material — the lens — also changes the image we see coming from the source. The curvature of the lens affects the direction the light is bent. In the case of light coming from outside a sphere of water, the light hitting the top of the drop gets bent down, light hitting the right bends left, and so on.
And one other thing: the path of light bends whenever it passes from one medium to another, so it bends if it’s going through air and then hits water, and it also bends if it’s going through water and hits air!
So now we can figure this all out. Read More
Traveling over west Africa at 8 kilometers per second in the International Space Station, astronaut André Kuipers took this eerie and lovely picture of a storm cloud just as it was illuminated by a lightning stroke:
[Click to enlighten yourself.]
Wow. This is easily as cool as another amazing shot of a lightning-illuminated cloud over Brazil taken from space in 2011, too.
And hmmmm. Scientists have detected gamma rays — extremely high-energy light — presumably generated by lightning storms and shooting straight up into space. I hope nothing makes André stressed any time soon. The ISS is no place for him to Hulk out!
[P.S. Before anyone asks -- and as much as I hate to explain a joke, I guess I really should in this case -- the gamma rays emitted by lightning storms are extremely weak, and not a danger to the astronauts.]
There’s a lot more going on over your head than you know.
For example, the atmosphere of the Earth thins out gradually the higher you go, and when you get to about 100 kilometers (60 miles) up, different physical processes become important. One of them is called chemiluminescence — light produced by chemical processes. This can make the upper atmosphere glow in different colors. It’s faint, and best seen from space… where we conveniently keep several astronauts. Neuroscientist and amateur video maker Alex Rivest has collected pictures of this airglow taken by astronauts and made this eerie and beautiful time lapse video:
Alex took the original astronaut pictures and enhanced them somewhat to bring out the faint airglow. You can see it in lots of pictures taken from the space station, and I’ve commented on it many times. One thing I’ve been meaning to do, though, is find out what the physical process is that’s causing the air to glow, and why it creates different colors — you can clearly see green, yellow, and red glow in many of the pictures!
Alex comes to the rescue on that as well. On his blog, he discusses how he made the video and why the air glows (based on a somewhat terser explanation at the Atmospheric Optics website).
The way this works is simple in general, though complicated in detail — much like everything else in the Universe! Basically, during the day, in the upper atmosphere ultraviolet light from the Sun pumps energy into oxygen molecules (called O2; two oxygen atoms bound together — this is the stuff we breathe). This energy splits the molecules apart into individual atoms, and these atoms have a little bit of extra energy — we say these atoms are in an excited state. Like a jittery person who’s had too much coffee, they want to give off this energy. They can do this in a couple of ways: they can emit light, or they can bump into other atoms and molecules and react chemically with them.
If you have an excited oxygen atom sitting in space all by its lonesome, it can either dump that energy by emitting green light or red light. Usually, it’ll emit green light in less than a second after becoming excited, and it’ll emit red light on much longer timescales, like minutes. This is important, so bear with me.
This amazing shot was taken by astronaut André Kuipers from the International Space Station on May 5, 2012, as the perigee full Moon set behind the Earth’s limb. The Earth’s atmosphere bends light from the Moon, acting like a lens, pushing the bottom part of the Moon up into the top.
Science once again saves me from embarrassment. I was pretty sure the Moon wouldn’t take it personally.
Image credit: ESA/NASA
One of my new favorite sites is Fragile Oasis, a blog where astronauts write about their experiences in space and on Earth. Don Petit, an American who has taken so many of the amazing pictures that have graced not just this blog but have gone viral across the web, posted a nice description of taking star trail pictures on orbit. This one in particular is surpassingly beautiful:
You can see part of the International Space Station at the top (I think that’s the lab section, with the node Destiny and the JEM facility, but I may be mistaken). The stars are blurred from motion, with the thickening on the right of the Milky Way, the combined light of billions of stars.
The slight motion blurring makes it look like the ISS is moving at warp speed over the planet. The Earth’s atmosphere is the thin green/brown haze over the Earth’s limb, with the top sharply defined by the aerosol layer. The red glow is interesting. That may be an aurora, but it might also be an internal reflection; Don shot this through the cupola window. Reflections plague the shots sometimes… but my gut tells me this is auroral in nature.
Either way, this is a stunning shot, and I found Don’s description really interesting. What an opportunity, to see the Earth from above all the time, and to be able to place it so well among the stars where, honestly, it rightfully belongs.
Image credit: NASA
The European Space Agency periodically sends an Automated Transfer Vehicle to the International Space Station to reload the astronauts with supplies. On March 28, ATV-3, named Edoardo Amaldi, docked with the ISS. Astronauts on the station took this unbelievable picture of it as it approached:
[Click to massively embiggen. And you really, really want to.]
Wow. You can see the thrusters on the ATV burning to control its approach, like it’s right out of Star Trek! The stars, the green and brown aerosol layer over the Earth’s limb, the city lights slightly blurred from the ISS velocity of 8 km/sec – it gives such an eerie and unearthly feel to the picture!
As, I suppose, it should.
The ATV is amazing: this uncrewed machine can dock with the ISS using just GPS and star trackers — telescopes that can determine position and orientation by watching the stars… like ancient mariners did. [Update/correction: The ATV doesn't dock with ISS using just GPS and star trackers; it makes its approach using those. Once it's close enough, a more sophisticated laser guidance system is used.] This mission carried oxygen, water, hardware, spare parts, food, and even clothing for the astronauts.
While it’s docked, it may also be used as a booster, gently pushing the station into a new orbit to avoid space junk, or to boost the orbit higher. Although there’s almost no air up there, there’s some. Over time, as the ISS plows through these rarefied molecules, it loses orbital energy and drops into a lower orbit. Periodic reboosts are necessary, and the ATV can be used for the job.
The ATV can stay docked for up to six months or so. After that, it undocks, de-orbits, and burns up in Earth’s atmosphere, making a spectacular fireball. A blaze of glory, you might say, for a machine that helps keep humans in space.
Image Credit: NASA
On March 4, 2012, the International Space Station passed over the Indian Ocean. Solar activity was high, and a gorgeous aurora raged in Earth’s upper atmosphere, yet still below the astronauts. On board the ISS, an astronaut took a series of still photos which were later put together into this video:
[Set the resolution to hi-def to really see the detail.]
Isn’t that lovely? I added the music (Supernatural by Kevin MacLeod at incompetech.com). Did you spot the moving light, traveling from left to right just as the video begins? That’s almost certainly another satellite, moving along its own orbit hundreds or even thousands of kilometers away.
I’ve written about aurorae (like here) and this method of time lapse photography many times; check out Related Posts below. With the Sun still being tempestuous, expect to see lots more gorgeous photography of our active geomagnetic field over the coming months!
Tip o’ the spacesuit visor: Remi Boucher. Credits: Image Science and Analysis Laboratory, NASA-Johnson Space Center. "The Gateway to Astronaut Photography of Earth." Here’s the original footage. Music: Kevin Macleod, Incompetech.com.
Hey, guess where I’ll be?
Yeah, there. Well, a little to the left of that big blob. Ypsilanti, Michigan, to be exact. On February 15th I’m giving my "Death from the Skies!" talk at Eastern Michigan University at 7:00 p.m. It’s free, so if you’re in the area drop on by! I lived in Ann Arbor for three years, so it’ll be cool to head back there.
And if you live in the Bethlehem PA area, I’ll be at Geroge Hrab’s concert a few days later! And then the live Nerdist podcast in Boulder March 2, and then SXSW on March 12th, and more stuff coming too.
Geez, I need to post a calendar. OK, I’ll put that on my list. If only I had a calendar to remind me…
Tip o’ the spacesuit visor to Fragile Oasis for the picture, which was taken on the ISS on January 30, 2012, because I assume the astronauts were excited that I’d be there. Credit: Image Science and Analysis Laboratory, NASA-Johnson Space Center. "The Gateway to Astronaut Photography of Earth."
Thanks to astronaut Ron Garan on Google+, I was alerted to some amazing footage of the Moon setting as seen by astronauts on board the International Space Station. I uploaded it to YouTube and added some comments to show you something really cool…
[Set it to high-def and make it full screen!]
Astonishing, isn’t it? As the Moon sets, you’re seeing it through thicker and thicker air. The air acts like a lens, bending the light upward. The part of the Moon nearer the Earth’s limb gets bent up more, so the Moon looks like it’s getting flattened. Watch it again; the top of the Moon doesn’t appear to be affected much. It looks more like the bottom slows down and the top pushes into it. You can read about this effect in more detail in an earlier blog post.
Weirdly, as I watched the video, it looked very much like the whole Moon was shrinking as it set, as if it were receding rapidly. When I saw that I knew intuitively that couldn’t be real; the ISS is only moving a few thousand kilometers over the time this whole video was taken (about ten minutes), not nearly enough to see that big a change in the size of the Moon. It’s 400,000 kilometers away, after all! So I measured the size of the Moon on the screen, and incredibly the width doesn’t change. Do you see it appear to shrink too? It’s an illusion!
Funny how our brain interprets such things. As if seeing a gigantic rock moving through the sky while perched on board a football-field sized satellite moving at 30,000 km/hr isn’t weird enough!
Credit: Image Science and Analysis Laboratory, NASA-Johnson Space Center. "The Gateway to Astronaut Photography of Earth".