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From a million miles away, NASA camera shows moon crossing face of Earth

nasa.gov

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Re: From a million miles away, NASA camera shows moon crossing face of Earth

#71

Post by gjm11 »

aik wrote: post #63
Vanayad wrote: post #59

What is the green "shadow" on the right of the moon? I'm not saying this is fake, but it looks like what I see in some greenscreen videos. I am really curious.

"EPIC’s “natural color” images of Earth are generated by combining three separate monochrome exposures taken by the camera in quick succession. EPIC takes a series of 10 images using different narrowband spectral filters -- from ultraviolet to near infrared -- to produce a variety of science products. The red, green and blue channel images are used in these color images. Combining three images taken about 30 seconds…

You'd think they could be smarter about combining the R,G,B images. E.g., allow for the thing under each pixel to have moved a little from one image to the next, look at all their narrowband images (which will typically be strongly correlated, especially for nearby wavelengths) to estimate how fast each part of the image is moving, and then to get a pixel in the final image combine its G with slightly offset (maybe interpolated) R and B.

Fiddly but hardly, er, rocket science.

(Of course for some purposes you really need the unaltered R,G,B images. But if you're producing a single RGB JPEG image for public consumption, that's not one of those purposes.)

[EDITED to add:] More difficult, I guess, is dealing with things that appear in only some of the planes. E.g., if G is taken last then there will be bits of Earth at the trailing edge of the moon in the G frame that have no counterparts in the R,B frames because the moon occluded them in those frames. So there will still be artefacts in the image. But I'd have thought they'd be less objectionable than the ones you get from just naively stacking the R, G, and B.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#72

Post by benihana »

gonvaled wrote: post #33
Cogito wrote: post #28

Earlier quoted context omitted.

The satellite, like everything in our solar system, is orbiting the sun. The sun-earth L1 lagrange point is between the sun and the earth (in every two-body gravitational system there are 5 lagrange points, so there are earth-moon lagrange points etc) These points are interesting because the orbit behaviour of items in them is weird! Specifically, the gravitational effects of the two bodies involved work in tandem to…

Interesting, thanks. I understand that the satellite needs to have some form of propulsion to keep it at L1 (it is unstable), so it must have a limited life. How long?

Every satellite needs to use propulsion for station keeping, satellites at LaGrange points included. Orbits aren't as stable in real life as they are in math.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#73

Post by grokys »

gonvaled wrote: post #27
rogeryu wrote: post #13

Earlier quoted context omitted.

Probably because that's the Dark Side of the Moon? https://en.wikipedia.org/wiki/The_Dark_Side_of_the_Moon

Is that a joke? The dark side of the moon is not more often dark than the visible side. It is just never visible from Earth.

I'd suggest following the link that was posted.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#74

Post by UserRights »

It is really cool how the NASA gives us a better understanding of the universe and our place in it by publishing all these nice pictures.

However, I would like to have one easy accessible source for all the nice pictures that is daily updated and could be synchronized to a local school server e.g. with rsync. Is there one "ḧere-are-all-the-pics"-ftp server anywhere? It is quite time consuming to browse the hundreds of NASA sites and download pictures manually - instead I would like to spend that time browsing a local incoming folder to select the best pictures.

Would be a great service to the world to have easier access to these pictures.

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#75

Post by bdavisx »

lcswi wrote: post #62
Tobold wrote: post #43

Someone tweeted this yesterday and some of the replies were really disheartening. Several people were calling it fake, with varying explanations of either "The earth is flat" or "Everybody knows the whole space program is fake". I knew people out there actually believe this, but damn...

Don't consider all comments to be honest, there are tons of bored trolls.

But also don't underestimate the stupidity, ignorance and/or anti-intellectualism of the general American (as well as other countries) population. Remember that 1/3 of Americans do not believe in evolution...

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#77

Post by TeMPOraL »

acqq wrote: post #58
TeMPOraL wrote: post #51

Earlier quoted context omitted.

Don't cameras have much better dynamic range, but we just limit it in software by reducing everything into 8-12bit/color images? After all, the hardware is just a bunch of sensors counting photons.

Go here and see for yourself, for example: http://www.dxomark.com/Cameras/Nikon/D810---Measurements ISO50, 14ev, ISO 12800 8ev. Then read here: http://photo.stackexchange.com/questions/21579/how-does-the-... We as humans can probably obtain 24 stops when our body uses all the tricks it has, not only optics of our "hardware".

Thanks for links here and under another comment, I learned something new today :).

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#78

Post by 2Pacalypse- »

UserRights wrote: post #74

It is really cool how the NASA gives us a better understanding of the universe and our place in it by publishing all these nice pictures. However, I would like to have one easy accessible source for all the nice pictures that is daily updated and could be synchronized to a local school server e.g. with rsync. Is there one "ḧere-are-all-the-pics"-ftp server anywhere? It is quite time consuming to browse the hundreds o…

Not quite what you requested, but NASA's Astronomy Picture of the Day[1] is very cool. It has an archive dating back to the 1995!

[1] - http://apod.nasa.gov/apod/

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#79

Post by jawbone3 »

jsingleton wrote: post #56
geofffox wrote: post #9

Maybe as interesting is where this satellite is: The Lagrange L1 point. The 5 Lagrange points in essence allow orbiting bodies to break Kepler's laws. A satellite a million miles closer to the Sun shouldn't have the same orbital period as the Earth... but it does.

L1 in particular is perfect for measuring the solar wind and Coronal Mass Ejections as an early warning system [0]. DSCOVR (the probe that took this photo) is the successor to ACE which is used to predict Auroras amongst other things [1]. This data is released by NOAA as a forecast [2]. I built an Aurora simulator with a similar API [3], but I think that mainly uses magnetometers. [0] https://en.wikipedia.org/wiki/La…

Actually DSCOVR is a satellite that was supposed to be used for climate change research, but then Bush was elected... Though, this whole Sun monotoring thing is something that was added twelve years after the sattelite was done, an apparetly what got it flying

Re: From a million miles away, NASA camera shows moon crossing face of Earth

#80

Post by zymhan »

UserRights wrote: post #74

It is really cool how the NASA gives us a better understanding of the universe and our place in it by publishing all these nice pictures. However, I would like to have one easy accessible source for all the nice pictures that is daily updated and could be synchronized to a local school server e.g. with rsync. Is there one "ḧere-are-all-the-pics"-ftp server anywhere? It is quite time consuming to browse the hundreds o…

That does sound like a great thing to have. Maybe this is something Code for America http://www.codeforamerica.org/about/ can do?
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