Home, from the start of a long, long journey

By Phil Plait | August 31, 2011 6:13 am

Sometimes, my favorite pictures from space are among the ones that look least interesting… until you understand what you’re seeing.

For example, this doesn’t look like much, does it?

Ah, but that picture shows so, so much. It shows everything!

That’s us. You, me, everyone. That fuzzy blob on the left? That’s Earth. The one on the right: the Moon.

In this one simple picture, you can see everywhere humans have ever been; hundreds of thousands of years spent on Earth, and a few brief days on the Moon. And this picture was taken from much farther than anyone has ever traveled.

This view of our home worlds was seen by Juno, a spacecraft launched on August 5. By August 26th, when it took this snapshot, it was already nearly 10 million kilometers (6 million miles) away. And yet this is merely a baby step compared to its total journey: it will take a long, sweeping path to Jupiter, traveling nearly 3 billion kilometers before arriving at its destination.

Take another look at that picture. See how close together they look? It took humans more than three days to bridge that gulf from one of those clumps of pixels to the other.

Pictures like this are important. They remind us that of where we really are, how much we’ve achieved, how far we have to go. And that our planet really is just a pale blue dot, swimming in a vast, empty black ocean.

Of course, there are better words about this I can muster. Perhaps now would be a good time to refresh yourself about them.


Related posts:

- Juno on its way to Jupiter
- Best. Image. Ever.
- HOLY FRAK! Moon transits Earth!
- MESSENGER’s family portrait

Comments (55)

  1. Carey

    New desktop wallpaper.

    When someone asks me what it is, and I tell them, I expect them to say, “Why are they so far apart?”

  2. Shatner Basoon

    Oooh I can see my home from here : )

  3. Ella

    This might be a bit of a silly question, but why does the Earth not have more of a circular appearance in the photo? I know it’s not perfectly spherical, but in that photo it appears like a wonky sphere with a bit of a bulge.

  4. Steven

    This makes us realize how small we truly are, and very few people can truly make us realize that like the great Carl Sagan. Great post, and I agree with Carey, definitely a new desktop wallpaper.

  5. hhEb09'1

    “See how close together they look?”

    Part of the reason that they look so close, is they seem to be foreshortened (or, maybe, overexposed). The distance between them should be thirty times the width of the large one, it looks more like half that to me.

  6. M Tadano

    You are right. Even though you always have some pretty amazing pictures, video, and information regularly, this picture is cool for all the reasons stated. Makes you think. Thanks.

  7. Messier Tidy Upper

    By Jove ..er .. Juno! ;-)

    Great thought provoking image and poetic article. :-)

  8. OtherRob

    If you’d given me a cutout of the Earth and one of the Moon at those sizes and told me to place them in the proper relation to each other, I’d have put them much closer together. So I really do appreciate pictures like this.

  9. Messier Tidy Upper

    @ ^ OtherRob & #1. Carey & # 3. hhEb09’1 :

    See :

    http://blogs.discovermagazine.com/badastronomy/2011/02/24/how-far-away-is-the-moon/

    For a good demonstration on how far apart our Moon and Earth really are.

    ****

    Five Quotes to put some things in perspective.

    “If we could transport Phobos and Diemos to our own Moon, they would fit comfortably inside the wide crater Copernicus with room enough for two moons of similar size.”
    - Stephen James O’Meara, page 102 “The Demon Sprites of Mars” in ‘Sky & Telescope’ magazine, June 2001.

    “To get a sense of the scale of the Jovian system, consider that if the Earth was placed at the centre of Jupiter, our Moon would lie inside the orbit of [Jupiter’s nearest large moon] Io, while distant [outer moon] Sinope would be a third of way to Mars.
    - P. 186, Ferris, ‘Seeing in the Dark’, Simon & Schuster, 2002.

    “If our Earth is 1 cm from our Sun – & Pluto is 50 cm from it – then the edge of the Oort Cloud of Comet’s would be 1/2 a kilometer away!”
    - Brian Cox, Wonders of the Solar System documentary. (Paraphrased from memory so hope I’ve got that right but pretty sure I have. Circa March 1st 2011.)

    “Around us is a vast galaxy arrayed on scales so gigantic that galactic structure becomes discernible only once the solar system has dwindled to a dot the size of the period of this sentence.”
    - P.211, Ferris, ‘Seeing in the Dark’, Simon & Schuster, 2002.

    “Yet here we are with our eyes and our minds and our curiosity, six+ billion passengers aboard a tiny blue boat, bobbing and wheeling our way around one vast Catherine wheel among many.”
    - P.246, Ferris, ‘Seeing in the Dark’, Simon & Schuster, 2002.

    + Today that figure is apparently seven billion humans – less than a decade later.

  10. J Hinkle

    I think it is unfair to not credit Carl Sagan. This whole post is very similar to The Pale Blue Dot, yet you didn’t mention Carl Sagan at all.

  11. M

    The link to Carl Sagan’s “Pale Blue Dot” is a welcome and humbling addition to the post. Personally, though, I would recommend this version: http://www.youtube.com/watch?v=2pfwY2TNehw
    It has stunningly creative visuals put tothe music of Mogwai.

  12. hhEb09'1

    Hmmm, it appears that the path of Juno parallels the earth orbit for a while ( http://www.nasa.gov/images/content/582402main_MissionStatus_082411.jpg ), and Aug. 27 was close to a new moon, so that pic should show minimal foreshortening. They just look too close together, to me… :)

  13. Charlie

    #3 and #4, it looks to me like the if the moon is actually further away than the Earth in this picture. The full distance is viewed at an angle, making the moon seem closer than it would have otherwise been.

  14. Lascas

    U cant tell the distance from that picture…. so if the moon was closer to Juno and in the picture it would seem right on top of earth, would you say “oooh look, how cute it is the moon is so close to earth…”

    Unless someone can confirm the moon and earth were at same distance from the probe at the time the shot was taken, that picture means nothing. At best, gives you an idea..

    Other than that, great pic, keep up the updates Phil, i’m a great fan.

  15. Sharku

    @hhEb09’1 except if this shot was taken when the Moon is about 30° off the Earth – Juno line in it’s orbit, then the apparent distance (da) between the Moon and Earth would be about half of the real Earth – Moon distance (dr): da ≈ dr * cos (60°).

  16. Sam

    reminds me of carl sagans speech of earth floating in a sunbeam taken from voyager.

  17. Chris

    I think it’s the intensity which is causing the optical illusion of being farther away. Earth-moon distance is around 375000 km, compared to the 10 million km where this pic was taken. So Less than a 4% difference, and based on the geometry, probably less than 1%. Even with the inverse square law it’s not too much difference in intensity. The Earth is much bigger (and has clouds) than the moon making it look much brighter.

  18. Erulóra

    They probably look so close together because the angle of the picture is not perpendicular. The Moon may be a bit closer or farther away than the Earth in that picture.

  19. Mark

    It’s almost poetic irony that this view is pretty much what Galileo saw when he first looked at Jupiter.

  20. J Hinkle (12): Try clicking the link at the end of the post. :)

  21. Chris

    It makes me wonder every time we take an picture of the stars in the sky, how many civilizations are living out lives like ours, how many have a completely different existence, how many are looking at the sky for the first time wondering if anyone is looking back, and how many are millions of years more advanced than us.

  22. Nigel Depledge
  23. QuietDesperation

    This might be a bit of a silly question, but why does the Earth not have more of a circular appearance in the photo?

    Maybe the angle of the Sun. You’re seeing a gibbous Earth, not a full Earth.

  24. Grand Lunar

    Sagan’s words on this manner hold true well into this day.

  25. Messier Tidy Upper

    @13. M :

    The link to Carl Sagan’s “Pale Blue Dot” is a welcome and humbling addition to the post. Personally, though, I would recommend this version: http://www.youtube.com/watch?v=2pfwY2TNehw
    It has stunningly creative visuals put tothe music of Mogwai.

    Thankyou. That is a great one. :-)

    Those words of Carl Sagan’s there are, I think, some of the truest, finest and best ever spoken. My own all-time favourite videoclip for that is this one :

    http://www.youtube.com/watch?v=Sbq0WYnph0w

    accompanied with the music of Sigur Rós and some very thought-provoking and appropriate images.

    @26. QuietDesperation :

    “This might be a bit of a silly question, but why does the Earth not have more of a circular appearance in the photo?”
    Maybe the angle of the Sun. You’re seeing a gibbous Earth, not a full Earth.

    Indeed. Our world like Venus and our Moon and water has phases.

    Our planet is the Morning and Evening Star of Mars.

    (Plus for Jupiter and the planets beyond too – although it’d be fainter and kept closer to our daytime star from those further spheres.)

  26. alfaniner

    Interesting that some think they look really close together, and others think they look too far apart! It’s possible that it is not even at apogee, and hence could be even farther away.

  27. Chris S

    But, but … according to my calculations, I have personally travelled over 45 billion kilometers.

    Ok – I *was* riding on a planet at the time. But it’s all in your mode of transportation!

  28. VinceRN

    Great picture. I think few people (except here of course) have a good idea of the relative size and the distance of the moon. This gives a good perspective. My kids liked seeing it and I think it improved their understanding.

  29. I saw someone post the We Are Here video. Here’s an HD version of the same video: http://www.youtube.com/watch?v=zTip1RDYOJ8

    It’s a compelling way to express the message by using moving pictures that are also very dear to us. This one doesn’t have nearly as many hits but the quality is better than the 240p one. :D

  30. Marcus

    I personally love this version of the Pale Blue Dot. The visuals finally compliment the poetic words Carl is reading: http://www.youtube.com/watch?v=XEwdRE8MKQg

  31. hhEb09'1

    @CJ, the Odyssey pic looks better, but even it seems too close! :)

    The caption says each pixel is 900km, but I measure 370 pixels from earth to moon, so 333,000 km, but the caption points out the actual distance is 385,000 km

    @Lascas (#16), @Sharku (#17), @Erulóra (#21), I tried to look into the possibility it was foreshortened (see my post #14)

  32. Dragonchild

    One rumor I heard about Pale Blue Dot is that Sagan had to actually fight to get the picture taken. The story goes that other scientists were concerned that the Earth was so (relatively) close to the bright Sun that the latter would damage the sensitive optical equipment. This confounds me. Voyager 1 was already past Saturn and scheduled to have systems shut down as its power source waned; the “Family Portrait” (including Pale Blue Dot) were AFAIK the last photographs Voyager 1 took of anything. What kind of damage is there to be concerned about?

  33. Jes

    Absolutely humbling. I could never understand why anyone thought the little Pale Blue Dot was the biggest, most important thing in the universe. Perhaps to us, it is, but in the grand scheme, we’re nothing but a spec, gone in the blink of an eye.

    I too thought it looked too close, my first reaction was “huh, I thought it’d be farther away than that” even though I’m really not consciously aware of the distance in any relatable way, it was just a gut feeling. I love this photo.

  34. Dan

    Dragonchild,

    You are correct. Some scientists didn’t want the “pale blue dot” picture to be taken. My understanding is that this wasn’t because they were concerned about the optical equipment. It was because such a photo “wouldn’t be science.” To which I say, bah humbug! Talk about lack of imagination. Luckily Sagan, who appreciated that space probes offer us more than pure science, pushed to have the photo taken and got his way.

    I’m guessing the Voyager cameras are now beyond hope of salvaging, but I’d be very curious to see what they’re seeing now. The sun must look like an intensely bright point. The planets would probably no longer be visible.

    One question about the Juno photo: It’s taken from 6 million miles away, roughly the same distance that Voyager II took its iconic 1977 photo of the earth and moon together. So why in this photo are the earth and moon just points of light, whereas in the 1977 one from the same distance, you could see so much more detail?

  35. CJ

    @hhEb09’1 I did a quick calc by putting a ruler next to the monitor and using Earth as a baseline. On my monitor, Earth had a diameter of approx 6.5mm, and the Earth-to-Moon distance was ~190mm. The ratio between the two is about 29.23. Taking the actual mean diameter of the Earth and multiplying by the ratio gives 12,742 km x 29.23 ~= 372,449 km which is only off by 3%, so I figure my crude method got close.

    I also carry the impression that the gap should be larger, but that’s why we analyse the data instead of relying on what we might believe.

  36. hhEb09'1

    I counted the pixels, but I may have made a mistake somewhere. I’ll go back and look.

    I saved the image, re-counted, and I get 122 pixels between the two, and the earth image is about 8 pixels wide, that’s a ratio of 15.25

    Earth would actually be more than 8 pixels wide, because as someone noted, it would be gibbous rather than a disk. How are you measuring the earth disk?

  37. DrFlimmer

    @hhEb09’1 and others:

    You should take into account that the “Juno-Earth-Moon”-System is not necessarily a right angle triangle. The projection of the moon’s position with respect to earth will most likely not give you the full distance, but rather a shorter one.

    (Hard to explain. Probably, you should draw a picture where there is no right angle at earth’s position and the moon is either closer to Juno or farther away than Earth, but on a circle around it.)

  38. CJ

    @hhEb09’1 Sorry, I was referring to the Mars Odyssey pic not the Juno pic. For the Juno pic I got Earth at 11 px and the distance at 124 px, giving a ratio of 11.27 (with a resulting distance of 143,637 km between the Earth and Moon).

  39. hhEb09'1

    Thanks, CJ, that’s even worse! :) I was trying to be generous, and not count the last layer of pixels I guess.

    @DrFlimmer, yes, I thought of that–that it might be foreshortened (post#14). As CJ has verified, there should be about twice as much distance between them. However, the photo date is near a new moon, and the Juno track seems to parallel the earth orbit…

  40. In my opinion, Sagan’s “Pale Blue Dot” passage is quite possibly the most profound couple of hundred words ever written in the English language. Or any other language.

  41. Obviously fake. Where are the stars?

  42. un malpaso

    Look, I can see my Moon from here!

    (With apologies to @ShatnerBasoon and Sarah Palin :)

  43. analog

    @3 : because the earth is actually not circular but slightly ecliptic since the rotation of the earth spreads it along the equator. north to south pole differs by +43km. Also I think it may be partly night (left side).

  44. Dave

    Coming Soon to a laptop near you……..’Google Universe’!
    See where you live with our exclusive “Planet View” feature! ;-)

  45. klae

    @3 because of what #49 wrote. As well, since the earths tides are pulled on by the moon the earth seems to bulge towards the moon.

  46. I wish I was part of the JUNO journey which will never come back to Earth again. This is interesting. Whenever I see new frontiers like this it always boosts up my dream of becoming an astronaut the more. I Love SPACE Xploration. . .

  47. Kim

    It may not be well-known, but it was Carolyn Porco (chief scientist of Cassini) who guided Voyager’s camera to take the family portrait and Pale Blue Dot’s shot.

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