Earth and Moon, from Mars

By Phil Plait | March 3, 2008 6:13 pm

The instant I saw the avalanche image from the HiRISE camera on-board MRO orbiting Mars, I knew I would have a contender for my Top Ten Astronomy Pictures of 2008.

But then they released this one at the same time:

Yeah, that’s us. That’s home. We were 192 million kilometers (115 million miles) from Mars when HiRISE turned around and took this picture. Right away I could tell that was South America’s west coastline… which is incredible. I also was just starting to wonder about the Moon in the image when I read that it had been brightened artificially to make it easier to see; in general the Earth is 3-4 times more reflective than the Moon, so it’s a lot brighter.

The Mars-Earth-Sun angle was just about 90 degrees when this was taken, which is why the Earth and Moon are half-full. Note that in reality, the Moon is about 30 Earth-diameters away from the Earth, so we’re seeing some perspective here. The Moon was a day before third quarter when this was taken, so it was actually a bit closer to Mars than the Earth was when HiRISE snapped this picture.

Beautiful.

MORE ABOUT: Earth, HiRISE, Mars, Moon, MRO

Comments (64)

  1. JB

    wow,
    reminds me of similar picture taken by another craft..forget which one..puts thing in perspective…
    jb

  2. defectiverobot

    Wow. That is a cool picture. And oddly enough, the lack of stars in the image only enhances the beauty, and makes it look more real.

  3. aporeticus

    JB, you are probably thinking about this one:

    http://en.wikipedia.org/wiki/Pale_Blue_Dot

  4. Michelle

    you know, seeing our planet has become pretty common…

    …But as soon as you add “From Mars”, it suddenly becomes 1000 times more awesome! SWEET.

  5. Where’s the high resolution one?

  6. RayCeeYa

    Now we just have to convince people that that picture was taken through a telephoto lens and in real life the Earth Moon system would never appear that large to the naked eye, lest we encourage more of that “Mars is going to be bigger than the moon” nonsense.

  7. RayCeeYa

    That makes me think.

    Would the Earth and Moon ever appear as separate points of light if viewed with the naked eye from Mars?

    Any astronomers with an answer to that one?

  8. Yep, got chills and almost cried (probably just from sitting outside in the “cold”). That’s us. Beautiful, crazy, loving, violent, little us.

  9. shane

    Yep, beautiful. Desktop wallpaper… now.

  10. Doug Berry

    “Yet across the gulf of space, minds that are to our minds as ours are to those of the beasts that perish, intellects vast and cool and unsympathetic, regarded this earth with envious eyes, and slowly and surely drew their plans against us.” – H.G. Wells, “The War of the Worlds”

  11. PeterF

    I was just marveling at the archive of Earth/Moon flyby pics from the Galileo probe last night. Seeing the Earth at a distance is always chill-inducing….

  12. I wish they’d take a picture like that when (from part of Earth) Mars is occulted by the moon.

    Do you know if there is a version with the moon at the correct relative brightness?

    Also, the jupiter pic from their site is pretty stunning as well.

  13. Wow, that’s a breathtaking picture.

  14. trebuchet

    When I see something like that I’m thrilled and sad at the same time. Thrilled, obviously, at the beauty of our world, our universe, and the human achievement that makes it possible for us to see such images.

    And sad when I think of the many stuck in superstition and suspicion, anti-scientists, fundamentalists, hoax believers and the like who instead of celebrating our universe and our achievement, chose to deny reality.

  15. Jeffersonian

    hmmm…lack of stars…artifically brightened….what’s NASA hiding from us? Alien contact?

  16. Calli Arcale

    Would the Earth and Moon ever appear as separate points of light if viewed with the naked eye from Mars?

    One of the MERs (Opportunity, I think) took a picture of Earth from the surface of Mars just before switching off for the night. It appeared as a single point of light. I think the MER cameras would roughly approximate naked-eye viewing, at least well enough for this purpose.

    On the other hand, this was twilight. (The MERs, being solar-powered, are not well suited to nighttime observation.) Would a later-night viewing have produced better results? Would the human eye do a better job of “splitting” Earth and Moon? Is the Moon far enough away from Earth for that to be possible? Is the Moon bright enough to be seen from Mars at any time (eg. opposition)? I don’t know. I suspect not, however.

    There have been some really stunning Earth/Moon pics through the years, taken by deep space probes. There’s the “Pale Blue Dot” and also the Voyager picture taken shortly after launch, which was rather similar to this one. There’s Galileo’s breathtakingly sharp images of Earth from its last flyby. Cassini, alas, only imaged the Moon when it flew past and did not capture Earth. However, it *did* manage the second-most-distant shot of Earth; it took a very cool picture during a ring plane crossing. (I think BA blogged about that too, IIRC. It was pretty insanely cool.)

  17. Fred S

    Lab Lemming: That’s a great idea. It would appear as a transit of the Moon (across Earth). At least as cool as the Hubble pix of Galilean moons transiting Jupiter.

    RayCeeYa: Interesting question. You know I think it would be very close to the naked eye limit. By a series of WAGs* (based on rel. solar illumination of E vs V, rel. albedos, and rel. distances of each to the viewer), I’m getting that the Earth would appear about 2 mags dimmer from Mars than Venus does from Earth, so about -2, the Moon about another 4-5 mags dimmer than that, so around +2 to +3, and separated about 1 mrad when at greatest brilliance (not nec. the most favorable for separating them while both are naked-eye), which is about 3-4 arcmin, so yeah, I think you’d be able to see that. When we do get astronauts on Mars, I’m sure they’ll look for this–it would be way too cool (and awesome, not to mention inspiring PR for the space program) to pass up.

    *WAG = Wild-Ass Guess (BA: DIRBE DPI Tom K used to use this a lot, remember?)

  18. Dave Dubya

    They’ve already imaged Jupiter with HiRISE as well. I wonder if they could get deep-sky images too with it.

  19. Calli Arcale

    In case anybody is interested (I particularly like Earth/Moon pics from deep space):

    Mariner 10 pic of Earth and Moon (while departing Earth; Earth and Moon composited and adjusted to show relative scale)

    Earth and Moon pic by Voyager 1, on departure not a montage, this shows lovely crescent Earth and Moon; Moon brightened by a factor of three for visibility

    The Pale Blue Dot I know someone already posted it, but it’s too good not to post again. ;-)

    Earth and Moon from Galileo (artificially composited images of Earth and Moon, adjusted to proper scale and proper relative brightness, taken during Galileo’s Earth gravity assist)

    Cassini’s Pale Blue Orb (Earth, with a Moony bulge, seen from Saturn orbit, through the rings — I misremembered; it was not a ringplane crossing, but passage through Saturn’s shadow permitted safe photography in a Sunward direction; it was the same time they made that cool Saturn pic that appeared on the front of Nat Geo.)

    Galapagos from MESSENGER (this one lacks the Moon, but it’s still cool; taken during MESSENGER’s Earth gravity assist)

    Earth and Moon seen by Mars Global Surveyor, from Mars a useful comparison to MRO’s pic

    Earth and Jupiter from Mars, by MGS companion to the above pic

    Earth and Moon seen by Mars Odyssey 2001′s THEMIS (approx 2 million miles away; Mars Odyssey was just leaving Earth)

    And the MER pic I mentioned above was taken by Spirit:
    You Are Here – Earth by Spirit (taken at sunrise, not sunset, on Sol 63 of Spirit’s mission)

  20. Steve P.

    Is the apparent lumpiness of the Earth’s atmosphere just some sort of distortion?

  21. Buzz Parsec

    Would Martian Galileo have needed a telescope to prove Martian Copernicus was right? Or would the martians have suspected heliocentricity from antiquity from observing the Earth and the Moon?

    I think the subject has come up before on this blog whether you could see the Galilean moons of Jupiter without a telescope from Mars, and the answer was “No.” They would be farther from Jupiter, and brighter, but not enough farther and not enough brighter to make a difference.

  22. decius

    Astronomer,

    you are degrading the English language, which is not an uncommon feature among ordinary trolls, particularly those who are affiliated with religious groups while pretending to be scientists, such as yourself.

    Now, go and bend your knees in front of some imaginary deity and stop bothering the adults.

  23. Geophysicist

    WOW!

    That is all.

  24. shane

    Wow. One troll and at least 3 sock puppets.

  25. I think that seeing Earth (and thus the moon) from the surface of Mars is tricky, because the dusty atmosphere means that twilight is long and bright. That being said, the maximum earth-moon separation might be greater than the diameter of the sun as seen from Mars, if opposition is at martian perihelion.

    I’m curious what the brightest planet is as seen from Mars. My envelope suggests that Earth, Venus, and Jupiter should all max out around -2.4, plus or minus.

  26. Podster

    I think Isaac Asimov – greatly missed – would have loved this post.

    As soon as I saw it, I immediately thought of his “The Missing Item”, a ‘Black Widowers’ short story.

    In the story, Henry (the mystery-solving butler) proves that a man – a member of the Tri-Lucifer sect – hasn’t really visited Mars (by astral projection) by pointing out that his description of the night sky from that planet was wrong.

    One of the characters in the story also (almost) comes up with a list of the 12 brightest objects in the Martian night sky. I leave it to you, BA, to see if it’s (mostly) correct or not.

  27. The lack of stars in these pictures obviously mean the photos have all been faked. Everyone knows the Earth is flat after all.

  28. Dennis

    I agree with Geophysicist

    WOW!!!

  29. Wouter Lievens

    This is very Saganesque. Truly beautiful. I have a new desktop background.

  30. MorsDei

    “that’s us. That’s home.”

    I see what you did there. (or at least you’re channeling his ghost)

  31. Anonymous

    According to my rudimentary back-of-the-command-line calculations, the separation of Earth and Moon is about 23 arcminutes when Mars is closest to us (that’s almost as big as the apparent diameter of the Moon, as seen from Earth), but drops down to less than 4 arcminutes when Mars is in opposition. Note that, however, that Earth is practically an inner planet from a Martian standpoint, with the largest elongation being some 49 degrees (for comparison, Venus’ largest elongation is 43 degrees), so the viewing geometry may not always be ideal.

    By the way, Arthur C. Clarke wrote a beautiful short story called Transit of Earth, in which an astronaut observes the Earth transiting in front of the Sun. More at: http://en.wikipedia.org/wiki/Transit_of_Earth_from_Mars

  32. Chas

    Podster: You beat me to it!

    One of the characters in that story goes through the math (on the back of a napkin) to get the relative magnitudes of the Earth-Moon system and calculate the visibility.

    Many of the Black Widowers stories were a bit contrived, but still fun reads (was anything by IA not?)

  33. TierOneGirl

    Awesome!
    “Earth and Moon pic by Voyager 1, on departure not a montage, this shows lovely crescent Earth and Moon; Moon brightened by a factor of three for visibility”
    That one resembles this one.

  34. Nigel Depledge

    Calli Arcade said:
    “On the other hand, this was twilight. (The MERs, being solar-powered, are not well suited to nighttime observation.) Would a later-night viewing have produced better results? Would the human eye do a better job of “splitting” Earth and Moon? Is the Moon far enough away from Earth for that to be possible? Is the Moon bright enough to be seen from Mars at any time (eg. opposition)? I don’t know. I suspect not, however.”

    Remember that Earth is an inferior planet as viewed from Mars. You would only ever see Earth as a morning star or evening star (a bit like seeing Venus from Earth), never during full night.

  35. Indescribable!!!
    Such a pity that this serene image has been spoiled by posts such as those from Decius and Astronomer.

  36. Calli Arcale

    D’oh! Good point, Nigel Depledge. I hadn’t even thought of that. Of course, that makes me think of another question that would be helpful for the folks doing back-of-the-envelope calculations about the Moon’s visibility from Mars — what is Earth’s maximum elongation in Mars’ night sky?

  37. Manyguns

    The picture is amazing.

    @Decius: I bow to your insult slinging prowess

    @BA: Could I please please please have the IP address (stress on singular) for Astronomer, Mark, xylos and Craig? I promise I’ll play nice… enough

  38. Michael Amato

    This is like having a hubble space telescope around Mars. The images of Earth, the moon and Jupiter are great. I’m going to go to the web site to enjoy more pics.

  39. Melusine

    Very nice, definitely a Pale Blue Dot moment.

    Callie Arcale, great post, thanks for the links to those great images.

    Another picture I love is of the Sun from Mars’ surface. These images from the off-the-Earth perspective are definitely humbling (another Sagan comment: being an astronomer is a character building endeavor).

    As Nigel said, and the famous Cassini image shows, from such distances we look like what we see in our sky. Another twinkle in a vast sea of darkness. So cool.

  40. Calli Arcale

    I’m glad you liked them. ;) I had a stash of these and more on my old hard drive. I backed them up to a CD, but am not sure where the CD went…. Doesn’t matter; they’re all on the Web somewhere. ;-)

    It’s humbling to look at them, but in a breathtaking, awe-inspiring way. Plus of course it’s fun to say “I can see my house from here!” :-P I know, my house is too small to show, but somehow it makes the output of these probes so much more *real*, seeing them take pictures of our home. It’s a bit like playing around with Google Maps to look around your hometown. It might seem frivolous, but there’s something almost magical about the whole thing. Sagan and his cohorts had to fight to get the Solar System self-portrait made, even though there was really no competition for Voyager 1′s cameras, way out there in the hinterlands of the solar system, precisely because it seems somehow frivolous to use this expensive spacecraft designed to study other worlds to take a look at our own. Especially since that look is so inferior in quality to what you can get from closer spacecraft. But there is a magic to these pictures that can’t be quantified in terms of scientific or financial return. I think the best use of these pictures is to grab the public’s attention. And they *work*.

  41. Wow, really puts things in perspective for you…

  42. Paul Caggegi

    that’s beautiful. Take THAT Flat Earth Society! lol.

  43. Rod

    Dave:

    We can’t really do deep sky observing with HiRISE, because our CCD array works in a “push broom” fashion – meaning that we can’t do point-and-shoot images. Instead, to get an area of sky, we actually have to roll the entire spacecraft in such a way to scan an area of sky across our telescope’s focal plane. This effectively limits how deep in magnitude that we can go.

    We have taken some star fields for calibration work, but they haven’t gone very deep in magnitude since we can’t do the long exposures that frame cameras do. So deep-sky observing is almost completely out of the question. In addition, our targeting specialists would probably revolt if we tried to regularly image non-Mars targets! Generating the special command sequences needed for MRO to target objects off-planet are difficult, time consuming, and prone to error.

  44. the links to pictures that Calli Arcale posted are wesome as well …
    can anyone get the dates of these pics … ???

  45. dai

    Home!
    Wow, these little dots we live in.

  46. Irishman

    Petrucio, that is the high resolution one. ;-) As Rod states, the HiRISE camera is not really intended for distant object viewing (other than viewing the one distant object, of course ;-) .)

    Calli Arcale, thanks for those. I really like the THEMIS one. That one shows the Moon and Earth at approximately max separation (perpendicular view). I’m particularly interested in scale presentations of the Solar System, things that show the bodies and distances between them at the same scale. That one is excellent.

  47. Simple Guy

    So I post this to Digg as soon as I see the post here. It gets a grand total of 2 diggs. Two hours later someone else posts it, and whaddya know, 1800 Diggs!!!. Mind you I linked directly to the HiRISE webpage (to try and save Phil’s servers :^) ). Which leaves me with two theories.

    1. There now exists “The BA effect” whereby even the slightest mention by Phil Plait or linking to him will gain you instant notoriety.

    Or

    2. Creationists are digging up Phil’s stories in an effort to crash his server’s and prevent him from delivering a healthy dose of reality to those who need it most.

    Either way, great job Phil

  48. Scott

    looking too close to the universe you cant see God’s handywork eh!.
    READ DARWIN’ BLACK BOX… if you still believe everything including yourself is a mistake YOU’RE the one ignoring the facts.

    You are part of the new religion, -science- men with nice placks on their wall tell you something and you bet your soul on it…

    I hope you search and find the truth…

    Love in Christ

    Scott

  49. Scott posts:

    [[looking too close to the universe you cant see God’s handywork eh!.
    READ DARWIN’ BLACK BOX… if you still believe everything including yourself is a mistake YOU’RE the one ignoring the facts.
    ]]

    Behe’s “Darwins’ Black Box” had a number of problems with it. Basically, he said that a number of biological structures were “irreducibly complex” that really weren’t. The mistakes vitiated his whole thesis.

    [[You are part of the new religion, -science- men with nice placks on their wall tell you something and you bet your soul on it… ]]

    Placques. And the whole point of science is to actually find out how something works, not to depend on authority figures to tell you about it.

    [[I hope you search and find the truth…]]

    Agreed, and in your and my case we have. But please don’t tie your evangelism to your views about creationism or science! I know from personal experience that creationism is a big stumbling block for a lot of non-believers. Right or wrong, evolution is part of what they’ve believed since they were kids, and attacking it makes them think everything you’re saying is wrong and doesn’t need to be listened to. I really think creationism has turned more people away from Christ than it has led to Him.

  50. galilayo

    The atmosphere is hyperboley in the sense that the moon is in constant pressure from its surrounding waves which would infact make the earth very lumpy indeed(i studied this many years and this picture is one of the best snap photos that we have, if in fact there were stars you would not be able to see the earth,(or moon in the sense of atmospheric pressure) but anyways this picture is very beautiful and remember the atmospheric pressure is all that matters in a world of planets in fact there are many oter universis but i aint talkin about that now nigga i got food to eat peace niggas.

  51. B Fenerty

    Thoughts on processed images:

    Re lumpy atmosphere or missing stars, anyone who follows the link Phil gives to the source page of the Earth and Moon photo will see in the HiRISE Operations Center’s caption that the image was processed to some extent. In this case a good thing – for reasons given there.

    Processing, as likely all readers here know of course, is actually often essential to obtain a meaningful image. (Think of infrared images of deep space objects: should they be left in infra-red? Well, sure if someone’s eyes can see infrared, but then they’d be of interest to medicine for at least one reason, ha.)

    As for missing stars, if that were to bother anyone, a few unshown stars are indeed in the background vicinity of the Earth and Moon HiRISE image.

    But, at least per my planetarium program, Earth from Mars was roughly at, shall we say, a noticeably-bright magnitude of -3.05, our Moon at a slightly fainter 1.01 (original magnitude which the linked website says they adjusted in processing). However, the brightest nearby star would be TYC6842-1271-1 at a much fainter magnitude 9.75. (Remember that scale is not linear, so “much fainter” is correct.)

    The HiRISE people could have also processed this faint star to appear, to keep some potential skeptics happy, but there are only two or three more stars at even fainter magnitudes in the photo’s area, and whatever else is back there is so much fainter even my planetarium program doesn’t bother listing them. Probably a few hundred super-super-faint galaxies? (But…if you know and like Malin’s astrophotowork well then maybe the unshown background stuff does matter…) Anyway, anyone really wanting the image processed even further to show the stars might be rather like listening to a recording of wonderful heavy surf crashing against a rocky shore, and criticizing it for not including the sound of some tiny twig falling inland in a thick forest half a kilometer back from the shore. (Think Long Beach, Vancouver Island, or Agate Beach on Haida Gwai, which BTW is a memorable verrry dark-sky observing site.) But for most of us I suspect that the sound of waves and few faint seagull calls would likely portray the heart of the location very sufficiently, likewise seeing the Earth and Moon without stars, as defectiverobot indicated March 3rd, presents a beauty not requiring anything more. (Unless of course someone is actually from unshown star TYC6842-1271-1!)

    At our science centre where the public also get weekly free telescope viewing I give very informal talks to adults and kids, including Keynote (powerpoint-on-Mac) images. Processed images too! (Will include the HiRISE EArth and Moon next time.) There, even the kids realize it is okay, even necessary, for astronomers to process images from Hubble etc into colourful deep space objects. They see details revealed in diverse ways that set them to wondering and learning. They don’t waste time bad-logic-ing and conspiricizing if there’s such a word. Some even begin to grasp why, for example, many astronomers use FITS files rather than the far more limited jpgs and tiffs the public are more familiar with. By processing images several different ways from data-thick originals, the very same source images can reveal much useful diverse info, as well inspire future scientists among those youngsters who have the good fortune (or blessing, your choice) of living in a remarkable time of wonder and discovery.

  52. Nigel Depledge

    Scott said:
    “looking too close to the universe you cant see God’s handywork eh!.
    READ DARWIN’ BLACK BOX… if you still believe everything including yourself is a mistake YOU’RE the one ignoring the facts.

    You are part of the new religion, -science- men with nice placks on their wall tell you something and you bet your soul on it…

    I hope you search and find the truth…

    Love in Christ ”

    Well, Scott, isn’t it a pity that not only is Darwin’s Black Box wrong in every important respect, but that its author, Michael Behe, actually lies in his follow-up book The Edge of Evolution.

    Behe claimed that HIV has not evolved any new biochemical interactions. A graduate student, who blogs under the name ERV and who works on virus biochemistry, called him out, pointing out at least two biochemical interactions that have evolved in some strains of HIV but not others. Behe’s response was both rude and irrelevant, completely ignoring ERV’s substantive point that refuted Behe’s claim.

    Is Behe the person you wish to regard as an authority? Really?

  53. harry

    GOD IS GREAT AND MD WODERFUL THINKS GR8T PIC

  54. donna taylor

    Hi home. From far away you look like a warm beacon..and yet so fragile

  55. really awesome view of moon…………..

  56. Chip

    Phil also wrote: …”in reality, the Moon is about 30 Earth-diameters away from the Earth, so we’re seeing some perspective…”

    I think this means that in perspective, the image we’re seeing of the Moon appears closer to the Earth because it is closer to us in its orbit as it swings around the Earth and not simply photo-shopped and moved closer to Earth within the photo?

  57. Instant Help Hotline

    Very interesting topic…let`s start with some physics lessons about the planetary constellation: Earth is circling the Sun in a inner, smaller orbit than Mars on an outer, larger orbit. Good ol’ Earth with the smaller orbit diameter circles faster round the sun than Mars with the consequence that TWO earth years correspond to ONE mars year. The Earth overtakes Mars approx. every 779 days = 2 years. Then Sun, Earth and Mars are standing opposite to each other. At that time, Mars can be observed best and presents his most beautiful perspectives! He appears as pretty reddish, striking star on the night sky. Attentive viewers are even able to see some loops he performs.
    I hope I could help you. A pity and fatal that those two beautiful planets meet so rarely. Lost in space..

  58. Instant Help Hotline

    ..itsalljustanillusion – true! ;-)

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