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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

#81

Post by leonardinius »

2Pacalypse- wrote: post #78
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/

Thanks for sharing. I think I will spend next several hours digging through.

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

#82

Post by sp332 »

gonvaled wrote: post #35
avar wrote: post #29

Earlier quoted context omitted.

You can get the answer to all these questions by reading: https://en.wikipedia.org/wiki/Tidal_locking and: https://en.wikipedia.org/wiki/Orbit_of_the_Moon

So, the Moon orbiting plane is close to the ecliptic, and the satellite is in the ecliptic (L1 is in the ecliptic). I do not get this: > About twice a year the camera will capture the moon and Earth together as the orbit of DSCOVR crosses the orbital plane of the moon. (nitpick: the DSCOVR has no "orbit" around the Earth, since it is in the L1 point) Since the Moon's orbit and the ecliptic are so close, I would expec…

DSCOVR is orbiting the sun and the earth at the same rate. In one year it will go once around the sun and once around the earth.

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

#84

Post by oaktowner »

What struck me about this was how huge the moon looks compared to the earth. We are used to seeing this as a small object in the sky (after all, it's 2000 miles across and 200000 miles away).

But when viewed from afar...you're seeing an object with an 8K mi diameter and another with a 2K mi diameter, not that different in size at all.

Which, I guess is another way to say: the earth just ain't that big.

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

#85

Post by Steuard »

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…

It's not quite what you're asking for (though I haven't looked around for alternate interfaces), but the NASA Photojournal site is really nice: http://photojournal.jpl.nasa.gov/index.html

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

#86

Post by RogerL »

gurtwo wrote: post #32

Why don't we see the Moon's shadow projected over the Earth in the pic? I guess it has to do with the relative distances of the 2 bodies to the Sun and the Moon's penumbra or something. Can someone make a digital image simulation of this to verify?

What shadow? When is the last time you walked out the door in the daytime and it was dark because the the moon was casting a shadow? That only happens during eclipses.

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

#87

Post by bpeebles »

oaktowner wrote: post #84

What struck me about this was how huge the moon looks compared to the earth. We are used to seeing this as a small object in the sky (after all, it's 2000 miles across and 200000 miles away). But when viewed from afar...you're seeing an object with an 8K mi diameter and another with a 2K mi diameter, not that different in size at all. Which, I guess is another way to say: the earth just ain't that big.

These pictures were taken "only" 1,000,000 miles away, so the Moon is significantly closer to the camera than Earth was, which makes it appear larger compared to Earth than it really is. The true size comparison is more like [0]. The effect is also more because the

[0] http://qph.is.quoracdn.net/main-qimg-5bff56bc0b31f8b7395bdbe...

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

#88

Post by Steuard »

TeMPOraL wrote: post #50
acqq wrote: post #15

Earlier quoted context omitted.

Note that the Moon is fully lit by the Sun (it's a "full Moon" from the perspective of the satellite). And it's gray on the picture, as the Earth is significantly brighter. Now, you can check it yourself, take the best camera you can have, go one night when the Moon is full somewhere outside of the city where you see the stars and then try to make a photo where on the photo both the stars and the Moon surface are vis…

Isn't this just because of the processing? I imagine if you took additional logarithm of the values returned by the sensor, you could have both starts and the bright moon visible at the same time.

That's basically the idea behind HDR (High Dynamic Range) imagery in photography/photo processing. (And my understanding is that it's hard to figure out exactly what the best scaling function is in order to mimic typical human perception: it's not just a simple log.)

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

#90

Post by jeffwass »

aspirin wrote: post #2

Is this the real reflectance of the moon? Seems so dark. Usually we see the moon at night surrounded by night sky, which probably skews our perception of the real color of the surface material.

Conversely, what I thought was pretty cool is seeing the reflection of the sun off the oceans, roughly in the middle of the earth 'disc'. You can see a fuzzy bright spot that stays in the middle of the disc as the earth spins.
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