back to article Pale backside of lovely Luna flits past in imagery from 1 million miles out

A million miles out in deep space far beyond the Moon's orbit, closer in to the Sun, lies the L-1 Lagrange point. Here sits the DSCOVR spacecraft with its EPIC instrument pointed back at Earth. NASA has just released some EPIC images, showing the moon zipping past in front of Earth. Here they are: Moon transit of Earth. …

  1. Anonymous Coward
    Anonymous Coward

    Shouldn't there be an eclipse if the moon goes between L1 and Earth?

    The next eclipse is due in mid September.

    1. cray74

      Re: Shouldn't there be an eclipse if the moon goes between L1 and Earth?

      The platform is in a large, 6-month halo orbit around L1, so it's frequently quite off-angle to the exact Earth-moon-sun axis.

      1. Little Mouse

        Re: Shouldn't there be an eclipse if the moon goes between L1 and Earth?

        From that viewpoint, the moon would have been blocking any shadow...

        Well, kind of. Maybe.

      2. This post has been deleted by its author

        1. cray74

          Re: Shouldn't there be an eclipse if the moon goes between L1 and Earth?

          Thanks, Symon. I'm aware of both types of orbit, I just have "halo orbit" as a placeholder in my brain for any orbits around a Lagrange point. My mistake.

  2. Zuagroasta


    Indeed, and considering the side shown in the image is actuallz the brighter one - less basalt - it's really surprising how grey the old Moon really is.

    Makes me wonder how things would have gone if we had something like ol' Enchiladas for a satellite, throwing shadows at night and all that.

    1. Grikath

      Re: Albedo

      Around full moon the light is already strong enough to throw shadows that can be seen. Atleast by those who are not visually impaired and "night-blind".

    2. TeeCee Gold badge

      Re: Albedo

      Enchiladas for a satellite

      Mexican foodstuffs have a higher albedo than cheese?

    3. Cynic_999

      Re: Albedo

      By far the most of what is seen of the Earth from space is water (oceans and clouds) which reflect light quite a bit better than rocks and dust, so I'm not at all surprised that the Earth appears considerably brighter.

  3. King Jack

    Mind blown

    How does that craft maintain its velocity around the sun to keep it close to the earth? There is so much that can go wrong but still it works and send pictures back. I just can't begin to think about what it takes to put something like that out there. The skills and tech blows me away.

    1. cray74

      Re: Mind blown

      "How does that craft maintain its velocity around the sun to keep it close to the earth?"

      Gravity. It's at the Lagrange L1 point where the Earth's and Sun's gravity are about equal. They both help tug DSCOVR along. "Goresat's" orbit is similar to SOHO's (click de image links inside this one), but the cameras face toward Earth rather than the sun.

      1. DropBear

        Re: Mind blown

        Well, not exactly. In that case neither the Sun nor the Earth would "pull" on DSCOVR and it would fly straight off tangentially. The actual L1 point is not where the two gravitational forces are equal, but as Wikipedia puts it "The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to orbit with them". Not quite the same thing (incidentally, also explains why there are not one but five of them - the rest are definitely not anywhere gravitational forces alone could be "equal and opposite")... :)

  4. Anonymous Coward
    Anonymous Coward

    Looks fake!

    Seriously, that shadow on the right hand side of the moon?

    Photoshopped? Let the conspiracy theories commence!

    1. cray74

      Re: Looks fake!

      "Seriously, that shadow on the right hand side of the moon? Photoshopped? Let the conspiracy theories commence!"

      Note the specs on the camera.

      DSCOVR's "EPIC" camera doesn't have a single color imaging mode. Instead, EPIC - like a lot of cameras on space probes - takes monochromatic images at different wavelengths. To get a color image, you combine those. EPIC works across 10 bands from near IR to UV and - important to your point about a "shadow" - takes only 10 shots an hour the bands being scanned in sequential intervals.

      In short, you see a "shadow" because the moon is moving between the 10 different scans that make up one image. Notice how in enlarged views the "shadow" is actually green-ish?

      Mega-close-up for the green "shadow":

      1. cray74

        Re: Looks fake!

        Ah, here's some more accurate details about the green shadow and imaging process:

        DSCOVR "snapped the photos that make up the new time-lapse video over a 5-hour span on July 16. Each image combines three single-color snapshots. That origin can be spotted in the photos, which show a faint green outline on the right side of the moon's disk due to the system's movement during the photographing process..."

    2. Bill Gray

      Re: Looks fake!

      A key point: this occurred about half a day after new moon. As seen from earth, both the moon and the spacecraft were about ten degrees from the sun. So the sunlight is coming in from behind the spacecraft and a little to its left (in the north-up frame of this image). Thus, the shadowing on the right limb of both the earth and moon.

      Dunno much about the color part of this puzzle, but could easily imagine it being due to the earth being kept steady in the center of the picture while the moon was gradually moving.

  5. TheProf


    “It is surprising how much brighter Earth is than the moon,"

    Surely a NASA boffin can't be surprised by this.

    A quick Google search and; albedo Earth:0.30, Moon 0.12.

    1. Hugh Pumphrey

      Re: Bright

      I suspect that the NASA boffin didn't mean that he personally didn't know the Moon's albedo, more that most people find it surprising that it is so low because the only time they see the moon is against the background of space (albedo = 0.0000...). Compared to pure black, the moon looks white, so the natural assumption is that it has a fairly high albedo. I introduce the concept of albedo in a basic meteorology lecture, explain that the Earth's albedo is about 0.3 and ask the students to guess the albedo of the moon. Most of them go for values that are far too high. (The actual value is not all that well defined because it is strongly angle-dependent, as well as varying from place to place on the moon. But it is a lot lower than 0.3)

    2. ravenviz Silver badge


      Wolfram Alpha says 0.367

      Vangelis says 0.39

      1. Gordon 10

        Re: Albedo

        Is the difference due to the light from his chariots of fire?

  6. Geoff May

    "the wardrobe sized DSCOVR spacecraft"

    How many grapefruit in a "wardrobe"?

    1. Admiral Grace Hopper

      Re: "the wardrobe sized DSCOVR spacecraft"

      How many wardrobes in a bus?

      1. AbelSoul

        Re: "the wardrobe sized DSCOVR spacecraft"

        How many buses in an Olympic-sized Wales?

    2. Robin

      Re: "the wardrobe sized DSCOVR spacecraft"

      I saw a documentary once about some kids who found a whole forest and loads of other stuff inside a wardrobe. There was even a lion, some turkish delight and some kind of goat thing.

      1. Anonymous Coward
        Anonymous Coward

        Re: "the wardrobe sized DSCOVR spacecraft"

        and a cheeky cockney beaver.

  7. Anonymous Coward
    Anonymous Coward

    Is it just me, or does that have an uncanny resemblance to a cica-1986 sprite animation sequence ?

    1. Tony Pomfret

      It's just you ;p

    2. Sykobee

      Even the Atari ST could have animated those smoother.

      1. cray74

        Chop chop

        Even the Atari ST could have animated those smoother.

        Third parties have done great work turning Curiosity's landing-descent snapshots into very smooth videos. I look forward to seeing what you accomplish with the free, public images from DSCOVR.

  8. Ugotta B. Kiddingme
    Thumb Up

    The cosmic humor

    We've been mooned. BY the actual moon.

  9. Fullbeem

    Dark side of the moon

    Is now in the light

    1. Ugotta B. Kiddingme

      Re: Dark side of the moon

      "There is no dark side of the moon, really. Matter of fact, it's all dark." [/heartbeat]

    2. Will Godfrey Silver badge

      Re: Dark side of the moon

      "There is no dark side of the moon..."

      "Matter of fact, it's all dark"

      Wow! seconds apart!

      1. Ugotta B. Kiddingme

        Re: Wow! seconds apart!

        like minds, appreciating what is perhaps the greatest rock album of all time. And most certainly a significant contributor to my current level of hearing loss... Cheers.

        1. Jan 0 Silver badge

          Re: Wow! seconds apart!

          > greatest rock album of all time

          Aw, c'mon, for the Floyd it was all downhill from Zabriskie Point. Darkside can hardly be the greatest rock album of all time.

  10. A. Coatsworth Silver badge

    King of backcronyms

    This animation is goddamned EPIC! hope the person who concocted that backcronym for the camera array got at least a pat in the back.

    Of all the amazing space photos, from the pale blue dot to the Earth rise to Pluto's heart, this gif is got to be my new favorite.

    I have to concur with an Anonymous Coward up there: it looks fake. I know it is not fake, but it is surreal seeing something as common as the Moon over the Earth, from "behind". It makes me think of that Victorian engraving of an alchemist sticking his head outside of the Fixed Stars Dome, and looking for the first time at the "hidden machinery" that makes the Universe work (Wikipedia tells me it's the Flammarion Engraving)... Breathtaking stuff



    “a herd of about 6,000 COSMOCOWS live on the GREEN crater, close to the Mendeleev crater on the FAR SIDE.” ...

  12. fortran

    Lunar Imaging

    At any given time, 50% of the Moon is visible from Earth, and being tidally locked it is (nominally) the same 50%. When libration (correct word?) is taken into account, we can see about 59% of the lunar surface. DSCOVR will have perfect views (in many wavelength bands) many times, and could build up views of the Moon in each of those bands. As DSCOVR orbits L1 (and the Moon wobbles, and has tilt), how much of the lunar surface can eventually be seen by DSCOVR?

    1. Black Betty

      Re: Lunar Imaging

      All of it. Provided you don't mind the nearside being imaged from an extra 1/2 million miles or so.

  13. Anonymous Coward
    Anonymous Coward

    Where's the Nazi base?

    I was told there was a secret Nazi base on the dark side. Or maybe it was an alien base, I forget.

    1. MichaelBirks

      Re: Where's the Nazi base?


      They exist in a kind of Schrodinger-like superposition.

      I don't know if the Tycho Magnetic Anomaly exists in all states and just hasn't been discovered in some of them.

  14. Graham Cunningham

    Beautiful. Just beautiful.

    And so much to appreciate from the commentards.

    Dark Side - that's Floyd, as mentioned. It's "Far Side". Larson.

  15. mediabeing

    The moon looks more like a giant coconut from this perspective. It probably is, for clever corporations to come.

  16. Black Betty

    Someone got left out of the last shot.

    + 1

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