Near and Far

By Sean Carroll | October 30, 2006 8:59 pm

Confession time: I didn’t successfully figure out what these two crescents were, until I read the explanation at Astronomy Picture of the Day. Can you?


The big one is the Moon; the small one is Venus. A few minutes after this picture was taken, Venus was eclipsed by the Moon.

  • Brock Tice

    My first thought was that one of them was some kind of lens artifact. The truth is so much more interesting!

  • Al Z

    My guess was that the smaller crescent was our moon and the larger an atmospheric phenomenon of some sort. Great picture!

  • Supernova

    Sorry, the title of the post gave it away for me. :) Excellent photo!

  • Ali Soleimani

    It’s not to hard to figure out the small one is probably Venus, but I also guessed the larger was a lens flare, with this photo chosen for its resemblance to the Venus crescent. Should have thought about the scal more — the clouds fooled me.

  • PK

    Yes, I thought the large one was an atmospheric effect as well. I did not have a good idea of the relative apparent size of Venus and the moon. Now I do. What a fantastic picture!

  • joseph

    You have a very strange concept of “near”, Sean. Since when is the Moon near? I would’ve called this “far and even farther”.

    Although, of course, that would be much less poetic…

  • Pingback: JayH Log » Moon and Venus()

  • Cynthia

    And I thought I was being cast under Einstein’s spell: the spell that some-sorta-gravitational-lensing was taking place here. After all, it is Halloween. Then, unfortunately, reality hit me: only quantum – not general relativity – has the power to create spookiness.;)

  • Rob Knop


    I looked at it and thought, “Moon and sundog.”

    By the way, the Moon is near. So is Venus. Really near. I mean, really, really, really near. The distance from the Earth to Venus is more than a hundred thousand times less than the distance from Earth to the nearest star… and the nearest star is so close that in any drawing you see online of the Milky Way, the Sun and the nearest star are well within the same pixel.

    The Moon is near. Venus is near.

    So, for that matter, is the Virgo Cluster. They’re all part of the “local supercluster.” We’re gravitationally bound to the Virgo Cluster. It’s near.


  • Alex R

    I guessed correctly that it was the Moon and Venus, but I was a surprised by how bright Venus looked, as compared to the Moon.

    But then I realized: Hey, Venus is closer to the Sun, and of higher albedo than the Moon, of course its surface brightness is higher than the Moon’s…

  • Mark

    My first inclination was to blame it on an optics effect. When I read what it really was, I was impressed. Of course, I was thinking that the scale was something close to what is seen with the naked eye or with most typical cameras.

  • Troublemaker

    By the way, the Moon is near. So is Venus. Really near. I mean, really, really, really near.

    Well, near is relative. They’re far away compared to the size of a human. They’re far away compared to the size of an atom. They’re far away in Planck units.

  • Arun

    In this era, is there anything scientifically useful extractable from the occultation of Venus by the Moon? Or is it back to being merely something beautiful?

  • Lucky Jim

    In this era, is there anything scientifically useful extractable from the occultation of Venus by the Moon? Or is it back to being merely something beautiful?

    When wasn’t it merely something beautiful?

    And what is the current definition of scientifically useful, can it really be defined for things at present?

    The calculus involved in the timing of this image would probably bring any ancient astronomer’s heart to a near stop.

    This picture to me is not merely something beautiful – it sums up the failure of aristatilian philosophy to desribe the heavens, its a snapshot of the copernican revolution, and thank you note to newton for his calculus.

    What more can you extract?

  • Arun

    Lucky Jim,
    I was thinking of things like the profile of the Venusian atmosphere, better astrometry and the like. But now there’s better technology than having to wait for a occultation.

  • Eugene


  • Pingback: » links for 2006-11-02()

  • Aaron

    Whoaaaaaaaaa! My first guess was some sort of crazy atmospheric lensing, but this is SO MUCH COOLER!


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Cosmic Variance

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About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] .


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