31–40 of 159 posts
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.
Earlier quoted context omitted.
So the satellite is not orbiting Earth? What is the advantage of putting the satellite there, as opposed to a regular orbit?
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…
Moon is tidally locked to Earth, which is interesting. How long will this last? How long has this been going on? Does this happen to all satellites in all planets? Another question: is the Moon orbiting plane aligned with the Earth rotation axis? Why or why not?
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
Moon is tidally locked to Earth, which is interesting. How long will this last? How long has this been going on? Does this happen to all satellites in all planets? Another question: is the Moon orbiting plane aligned with the Earth rotation axis? Why or why not?
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
> 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 expect this crossing to happen more often (on every turn of the Moon around the Earth)
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?
So, even though a perfect alignment of DSCOVR (at L1), the moon, and Earth would mean a shadow and thus eclipse, the moon must be a little off that alignment on this pass, throwing its shadow into dark space, even though it looks very nearly aligned in the photos.
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Earth is a sunlit object in this picture, the luminosity is the same level as during the day on earth - would you see stars in your photos if you took a correctly exposed photo of something during daylight on earth? I don't think this would happen :) The dynamic range difference between day light objects on earth and the stars on the sky is huge.
The satellite is 1 million miles away from Earth at the L1 Lagrange point. What is it about optics that allows us to compare a photo of the stars taken at such a distance with one taken from the surface of the earth? [Edit: "compare", in the sense of understanding whether or not the stars will or won't show up in each case. I get that the laws of optics are the same throughout the universe.] > The dynamic range diffe…
The fact that the earth in the picture is lit by the sun and has similar luminocity levels to looking at the sky from the surface during the day.
The background of the picture (the stars) on the other hand, have the same meagre light they always have.
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?
Earlier quoted context omitted.
You mean like the moon? Yes. You mean like meteosat? No. A 4 metre wide object is going to be such a small proportion of the size of a single pixel that it will be completely invisible.
Does anyone know why they decided to go with just a 4 megapixel camera? I guess they could settle for taking more narrow images and recombining later but it seems better to take one image and crop if they are just interested in small parts. Plus you have the option for digital zoom.
I'd say because they have several other constraints the necessitate that, not because a 50MP wouldn't do. E.g. resistant to cosmic radiation, able to cope with the light extremes it needs to, etc.
Here they have some other factors I didn't consider: http://www.extremetech.com/extreme/134239-why-does-the-2-5-b...