If you're interested...
Pretty amazing to think this was taken from a million miles out.
NASA has released a splendid new pic from the DSCOVR satellite, newly arrived at point L-1 a million miles sunward from Earth. An epic e-pic from EPIC. DSCOVR's full name is the Deep Space Climate Observatory, so dubbed for its position at the Lagrange point one million miles away on a line from the Earth to the Sun, where …
Pretty amazing to think this was taken from a million miles out.
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Expectations were for a loss in quality from atmospheric and space weather effects, along with quality of sensors on the satellite itself. As it happens they've got lucky and the satellite sensors were at the higher end of the quality spectrum and the sensors and software can handle the atmospheric and space effects quite admirably. If you need an analogy it's a bit like buying a car with a stated mpg of 37 mpg and finding it actually does 37.1 mpg. It's not much, but it's better than expected.
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"If it's a point how come multiple spacecraft can occupy it?"
While gravity exactly cancels only at a specific point, there's still plenty of volume around it in which any force is very small. In fact, the L1 point (and L2 and L3) is an unstable equilibrium, so unless you're in exactly the right place any body will drift away from it. Since the point will move around a bit due to orbits not being perfectly regular (since there are more than two bodies in the solar system), even a single probe trying to stay exactly on the point will need thrusters to keep station. So since you're going to be doing that anyway, it's a not a problem to just get somewhere in the general vicinity where the forces involved are small compared to a random point elsewhere, and to use the thrusters that you'll need anyway to stay there. Incidentally, this is also why you only ever see natural objects at the L1-3 points, only at L4 and 5 which are stable.
Fed up with the unpromising British summer? Why not holiday in Solar L-1? With panoramic views of the entire planet and permanent sunshine you'll soon shrug off your seasonal affective disorder.
[Terms and conditions apply. The airline reserves the right to charge for oxygen, radiation shielding and fresh water. And a phone call back to Mum may have a 5 second delay on it]
Unless I'm misunderstanding, during an eclipse a camera there would see nothing but moon. If you stood on the sun (not recommended), the earth would be exactly covered by the moon. If you moved further to the far side of the sun, and could see through it, the moon would not cover the earth, but if you move towards Earth, the moon would appear to more than cover the earth's disk.
So... All you would see is the far side of the moon, well lit. Maybe with a little tiny shadow of yourself.
Distance from L1 to Earth 'De'~ 1,500,000 km.
Distance from L1 to Moon 'Dm' at closest point ~ 1,100,000km (approx.)
Diameter of Earth 'E'~ 12,742km.
Diameter of Moon 'M'~ 3 475km.
Moon's relative size to Earth when viewing from the perspective of L1:
M/E * De/Dm ~ 0.37
You are mistaken about a camera on the sun during an eclipse. The distance is so far away there would be almost no perspective and the moon would not appear to cover the earth. The moon does obscure the sun from the earth because:
Distance from earth to moon: Dem ~ 385,000 km
Distance from earth to sun: Des ~ 149,600,000 km
Diameter of Moon 'M'~ 3 475km.
Diameter of Sun 'S' ~ 1,391,684km.
Moon's relative size to the sun from the perspective of the earth:
M/S * Des/Dem ~ 0.97, so the from the earth the moon appears about the same size as the sun.
(exact proportions will vary depending on where in the orbit things are relative to perigree/apogee).
Feel free to work the numbers from the perspective of a camera on the sun!
Nice lot of math, but it misses the point. The Moon doesn't have to block out the entire Earth to make the picture boring; it only needs to block out the Moon's shadow. As a result, all the spacecraft will see is a transit of the Moon across the Earth, and it'll see one of those every couple months anyway.
We are capable of doing miracles like sending up this craft and yet we can't stop people from polluting the planet every day of their lives...
And, we are capable of doing miracles like sending up this craft and yet we can't stop killing each other over what it says in some old books, or in pursuit of money...
Go figure, indeed...
capable of doing miracles like sending up this craft and yet we can't stop killing each other
The one is, I suspect, tightly linked to the other. Without the drive and passion that leads some humans to kill one another, we'd probably never work up the collective enthusiasm to build the space craft. Oh well...
"It's way too far out to be the ISS, that orbits at 250 miles. Looks more like a dodgy pixel on the camera's CCD."
Well it might be but as there seems to be quite a few more around the image I'd guess they were stars.
Yep -just altered the curves on the high res-image - space is full of e'm
Quite possible it's Gamma Rays striking the CCD you see these artifacts on the raw CCD images on pretty much every spacecraft, they typically get removed in post processing before press release. The fact that the bright "Tan" coloured one in the bottom right is a horizontal smudge rather than a round blob indicates this to me. Gamma Rays are extremely directional and Stars are blobs.
can't wait to see what's sent back from this vantage point with the Moon in frame, side-by-side, Moon entering a lunar eclipse, Moon and shadow crossing in a solar eclipse, don't know the field of view, perhaps even an animation of the dance of Earth and Moon.
All a bit 'intro to 2001', only IRL! Wow!
I thought being at the lagrange point meant it was *exactly* between earth and sun and therefore has the sun exactly behind it. In those circumstances I would have expected the atmosphere boundary layer to look the same all around the planet.
However on the left side you can see a very sharp delimiter but on the right it is fuzzy...
can anyone explain me this phenomenon?
I noticed that too. My initial thought wouldn't be any where near conspicuous enough and would in theory be more pronounced on the other edge anyway. So it certainly ain't that!
The spot of sheen formed where sunlight is reflected directly back by the surface of level seawater appears to be centred somewhere around Acapulco - a significant offset to the left of centre. So it seems the sun was definitely shining over our left shoulder and not from directly behind us.
Looking at the high res on the monitor I have here, it seems to have pretty much the same sharpness both sides, however the left side seems to have a blue outline. Possibly is chromatic distortion. When you get this, it tends to show as e.g. green fringe on one side, and magenta on the other (or yellow/blue or something else, depending on the processing)
No, not CA either. The weird CA on many of the clouds including those at the extreme left looks like artefacts arising from subject movement between separate exposures for the colour channels. The blue outline should definitely go all the way 'round - it's what we breathe. The reason it isn't visible on the right hand edge is that that edge was in darkness. The viewpoint was not directly between the sun and earth but what looks like about 10° offset from that axis, which at a million miles range would mean a distance somewhere in the region of 200000 miles... which turns out to be the right sort of scale for a Lissajous orbit... so that'll probably be our answer.
Wild shot in the dark whilst bronco riding.
Could it be the amount of moisture / dust in the air due to temperature difference, one side will generally be slightly warmer than the other due to being in the sun for longer.
Yes, it's called the 'hemispheric long wave pattern' and at the moment it has four troughs (at other times I've seen three or five troughs). It is useful for long-range rain forecasts, e.g. http://www.weatherzone.com.au/long-range-forecast/28-day-rain/act/act
... the Earth is not depicted with the North pole at the top. The west coast of Ecuador and east coast of Florida are roughly on the same meridian, so the axis of the Earth in this photo is tilted by 25-30 degrees [1]. The North polar icecap is at the top left - is this just artistic presentation, or did somebody hang up the DSCOVR camera with a bit of string that's stretched?
[1] Estimated with NATO Standard Eyeball
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Of course, I know that the Earth's axis does have a tilt (23.4° from the plane of the ecliptic, according to a fine information source). However, I don't think that's the source of the unconventionality: at Northern hemisphere midsummer, the north pole would be tilted towards the Sun (and thus towards L1), and the photo was captured on July 6th, only two weeks after the solstice, according to the caption on NASA's press release. At the equinoxes, DSCOVR's view of the Earth ought to be tilted like this: maybe someone has made a decision always to depict the axis this way...
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