APOD: Flying Over the Earth at Night (2012 Mar 05)

[Sinan İpek]

Is the green curve above earth ionosphere? Does astronaust see that green curve with their naked eye or is it the result of long exposure photography?

[Greg C.]

For the first time, I understand when people say the earth itself is alive... the lightning, the aurora, land, and ocean. Really beautiful... and great job capturing it all.

[neufer]

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Is the green curve above earth ionosphere?

It is at the bottom of the ionospheric F region:

McGraw-Hill Science & Technology Encyclopedia: Airglow

<<The nighttime airglow (nightglow) is predominantly due to recombination emissions. The ionospheric plasma recombines near the bottom of the F region (150–200 km or 90–120 mi) where the densities and thus collision frequencies are higher, producing bright atomic oxygen (O) spectral lines in the red (at 630 and 636 nanometers) and a weaker green (558-nm) line.>>

Does astronaust see that green curve with their naked eye or is it the result of long exposure photography?

Astronauts can see it with their naked eyes:

Encyclopedia Astronautica (Mercury MA-8)

<<The Sigma 7 spacecraft with Astronaut Walter M. Schirra, Jr., as pilot was launched into orbit by a Mercury-Atlas vehicle from Atlantic Missile Range.

On Earth's nightside, Schirra reported that the Moon made an excellent yaw reference; after completing and reporting on the yaw maneuver, Schirra told Slayton in the Mercury Control Center that he had shifted back to the automatic system. By now the temperature had subsided enough to permit a quick drink of water. He took the opportunity during this respite to report that all systems were performing very well. So far he had felt only one unwanted spurt from a 24-pound thruster when he returned to fly-by-wire for a yaw-maneuver exercise. Becoming a little bored with automatic flight halfway around the world, Schirra shifted to the manual- proportional system and produced a similar moment of double authority. About two percent of the manual supply spat out in a pitchdown motion of the spacecraft. "It was my boo-boo," he confessed.

Over Muchea, Australia, on his second pass, Schirra began a more serious and considerably more difficult night-yaw experiment. He was to test his ability to use celestial navigation to align the spacecraft properly. Using star-finder charts, Schirra was supposed to orient himself by positioning Sigma 7 in relation to known stars or planets and the Moon. Then he was to test his sense of facing to the right or left of his flight path by watching the apparent motions of heavenly bodies. The pilot found that the airglow layer was an excellent reference for pitch and roll. This belt, which appeared very thick above the horizon, could provide reference for these attitudes quite accurately. For experimentation with the airglow layer, he positioned Sigma 7 so that it appeared to aim at the upper layer of the belt. The panel indicators then showed a zero reference in pitch.>>

[aussie ter]

beautiful, went by to quickly. dont recognise much . southern hemisphere would be nice. But still magical, awe inspiring but still somehow fragile

[Romagers]

The views are an excellent material. Several places can positively be recognized, as California in the U.S., then The Baja California Peninsula and the Gulf, Most of the Mexican territory, the Yucatán Peninsula, Guatemala and most of Central America, and Panama; then it switches to views over Antarctica and the Aurora Australis, then the Artic and the Auroras Borealis; the we can clearly see Southeastern United States, the Florida Peninsula with the Gulf of Mexico on the right, Cuba, Puerto Rico; it jumps after over the Baltic Sea, where we can clearly see the south of Sweden and Denkmark, the coast of northern Poland, Germany, Holland and Belgium with the coast of the English Channel (La Manche) on the right side while it passes over the center of Europe in a S.E. direction (we see the Mediterranean far down on the right) and it reaches over Italy, the Adriatic, Greece and Turkey, we can clearly recognize the shape of Cyprus in the middle of the Mediterranean and the West Coast of Turkey, Israel and Lebanon, the lights of Alexandria in Egypt with The Nile, and the Suez Canal to its left widening in the Red Sea with a global view of the Middle East where we can easily tell Saudi Arabia. It is a Great, material, however, in order to recognize all that above, we have to watch it over and over several times, as everything passes too fast. That was, in my opinion, a mistake done by the creators of the video, especially considering that the original material was taken at a much slower rythm (we have to remember that the ISS closes a whole turn around the Earth in 90 minutes [one and a half hours] and this video seems to make a whole turn in around two minutes!! That's the only thing to regret about, unfortunately, because for the rest is a fantastic thing!! Congratulations!!

[Chazb]

At 1:17 it is flying over the northern end of the Suez Canal heading south. That bright line to the right is the Nile River. I've been through that canal 18 times, recognized it immediatly.

[Dean Georges]

I thought I was special..... I recognized Florida and Italy... then I see everyone saw Florida & Italy. I tried to figure out Greece, but it was gone. What a fabulous
two and a half minutes. Isn't it a small world?
Dean G.

[agosnell]

very nice, thank you.

[Flyboy]

It would be better if you could tell where you were. I can only identify the 'boot' of Italy

[bruno giovanni]

For reasons that escape my understanding this is definitely not the video that was originally posted (which lasted about 5 minutes). However, after some search I think I recovered that old one at: http://www.youtube.com/watch?v=Ip2ZGND1I9Q. A nice feature in the old (that the new doesn't show) is at 3:47 and 4:38. The ochre-orange meandering ribbon is the Pakistan-India border (it appears as it were lighted. Could anybody confirm?). At 3:47, the dark patch on the upper left (north-east) is no sea, but Tibet.

Confirm came: http://earthobservatory.nasa.gov/IOTD/view.php?id=52008

[longtry]

Sorry for digging this thread, but I have a similar question with herpdederp, and it's definitely not airglow, owlice. If you pause the video at 0:29, you will be able to see clearly that the city lights on the left of the frame are green, too bright for the faint airglow to compete with and too concentrated on population spots, rather than spread out on the 100-250km height horizon.

The video maker's FAQ page points out that the photographed region there is Guatemala, and they happened to replace their street lights with LED just before the time of it being captured by ISS. But the reddit link discussion also reveals that the LED are actually white to our eyes, and their best guest is that there's some mechanism that makes the light appears green when seeing from space. What it is, is still a mystery. What do you think?

[owlice]

Sorry for digging this thread, but I have a similar question with herpdederp, and it's definitely not airglow, owlice.

Sorry, but I was responding to zijon's question (not herpdederp's) about the "somewhat greenish thin line just above Earth surface?", which is indeed airglow. I didn't answer the question asked, however, as the query was about the altitude of this line, not a request to identify it. I refer the reader to this lovely link for the answer to the question zijon asked.

[longtry]

Oops, sorry for wrongly addressing you on that part. Still, the other question stands I'd love to hear what theories us citizen scientists on this forum have to say about it..

[Chris Peterson]

Sorry for digging this thread, but I have a similar question with herpdederp, and it's definitely not airglow, owlice. If you pause the video at 0:29, you will be able to see clearly that the city lights on the left of the frame are green, too bright for the faint airglow to compete with and too concentrated on population spots, rather than spread out on the 100-250km height horizon.

The video maker's FAQ page points out that the photographed region there is Guatemala, and they happened to replace their street lights with LED just before the time of it being captured by ISS. But the reddit link discussion also reveals that the LED are actually white to our eyes, and their best guest is that there's some mechanism that makes the light appears green when seeing from space. What it is, is still a mystery. What do you think?

The first question I'd have is, does it appear green from space? It seems quite likely to me that this is an imaging artifact. Led lighting doesn't produce a continuum light source, and nearly all light sources that are made up of groups of emission lines or of odd mixes of wavelengths tend to produce images that look to be different colors than what our eyes see. What the camera records and what the astronauts see may be very different.

[longtry]

Hmm, interesting. It can be the cause, but IMHO it's unlikely. The video was made from images photographed by normal commercial cameras, as stated somewhere in the FAQ. They're designed to represent exactly what a person sees, or in other words they try to imitate what our eyes capture. Of course other cameras in IR, UV... see different stuffs, but I think if a visible spectrum camera produces different colors than a man's eyes perceive, then it fails as a camera.

Anyway, that's just my slightly educated guess, since I don't know for sure how modern cameras & that particular type of LED in Guatemala work. I just used the logic that manufacturers must be vying to make the most 'representative' camera possible, since the majority of consumers would want one that can capture their moments exactly as they experience them.

[Chris Peterson]

Hmm, interesting. It can be the cause, but IMHO it's unlikely. The video was made from images photographed by normal commercial cameras, as stated somewhere in the FAQ. They're designed to represent exactly what a person sees, or in other words they try to imitate what our eyes capture. Of course other cameras in IR, UV... see different stuffs, but I think if a visible spectrum camera produces different colors than a man's eyes perceive, then it fails as a camera.

Anyway, that's just my slightly educated guess, since I don't know for sure how modern cameras & that particular type of LED in Guatemala work. I just used the logic that manufacturers must be vying to make the most 'representative' camera possible, since the majority of consumers would want one that can capture their moments exactly as they experience them.

In fact, ordinary cameras do a terrible job at accurately representing colors from light that isn't produced by sunlight reflecting off of objects. Cameras are designed to capture ordinary terrestrial scenes, not unnatural light sources.

[longtry]

Then 1 way to make sure is to ask an astronaut to look out when the ISS flies over Guatemala for the color of the LED. Is there any method to contact them, make an official request or a petition or something like that?

[Chris Peterson]

Then 1 way to make sure is to ask an astronaut to look out when the ISS flies over Guatemala for the color of the LED. Is there any method to contact them, make an official request or a petition or something like that?

Yes, having someone simply look would be best. Of course, it's very possible the question could be settled by simply flying over the area in an airplane. I doubt there's anything special about being in space in terms of the color. (Some of the astronauts have a social media presence, and there are ways of asking questions via NASA, although with the current shutdown it's probably not so easy.)