Shooting the Moon

MoonThis is simply too cool not to share.

After voting for WDTPRS (which will take about 5 seconds) take a look at this.

This from Astronomy Pic of the Day.

About 1,300 images from the Lunar Reconnaissance Orbiter spacecraft’s wide angle camera were used to compose this spectacular view of a familiar face – the lunar nearside. But why is there a lunar nearside? The Moon rotates on its axis and orbits the Earth at the same rate, about once every 28 days. Tidally locked in this configuration, the synchronous rotation always keeps one side, the nearside, facing Earth. As a result, featured in remarkable detail in the full resolution mosaic, the smooth, dark, lunar maria (actually lava-flooded impact basins), and rugged highlands, are well-known to earthbound skygazers. To find your favorite mare or large crater, just slide your cursor over the picture. The LRO images used to construct the mosaic were recorded over a two week period last December.

That, folks, is very cool.

About Fr. John Zuhlsdorf

Fr. Z is the guy who runs this blog. o{]:¬)
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  1. Tony Layne says:

    I just wish one could get a glimpse, or even a glint, from the descent stage of the Eagle somewhere out there in Mare Tranquillitatis. That shot truly is too cool for school.

  2. Mike says:

    Fantastic. This is simply amazing stuff.

  3. Andrew says:

    Ecclesiasticus cap. 43:
    6 Et luna stat in tempus suum,
    in ostensionem temporis et signum aevi.
    7 A luna signum diei festi;
    luminare, quod minuitur in consummatione.
    8 Mensis secundum nomen eius est,
    crescens mirabiliter in consummatione.

  4. frjim4321 says:

    That is cool.

    Has mention been made here of the following site:

    It is fairly amazing. I saw an Iridium Flare right overhead the other night at it was fantastic!

  5. Venerator Sti Lot says:

    Thank you for sharing this! A site to remember. (Michaelangelo’s depiction of the creation of heavenly bodies in the virtual Sistine Chapel is even more attractively zoomable-into, than the lunar surface here, but that is no major quibble, not even necessarily a desideratum.)

    One thing I do not ‘get’ and am none the wiser about, after clicking the gloss-link on the site, is why it says “The moon rotates”. Isn’t “rotates” exactly what the moon does not do as it orbits? That fact may be interesting in itself – why does a (given) heavenly body rotate or not? – but that is a different matter.

  6. Legisperitus says:


    The moon does rotate, but it completes one rotation in the same time period as one revolution around the Earth. That’s how it keeps the same face toward Earth at all times.

  7. Legisperitus says:

    Also, the phrase “tidally locked” is the key to why the moon keeps the same face toward us. It’s the gravitational attraction between the moon and our oceans. The oceans “bulge” toward the moon as they rotate under it, and the mass of the oceans exerts enough corresponding attractive force back upon the near side of the moon to keep it from rotating away from the Earth. I’m not an expert, but I think it works something like that.

  8. Andrew says:

    I saw a National Geographic program explaining how life on Earth would not be possible without the Moon. Obviously, life on Earth would also be inconceivable without the Sun. And life on Earth would also be impossible if the Earth wasn’t tilted against its orbital plane about 23 degrees or if the Earth did not have a magnetic field to shield us from harmful radiation. It is stunning to consider how many variations favor life on Earth. This planet, surrounded by vast empty hostile spaces is teaming with life, and we take it for granted that the Sun will rise, and the rains will come, and our crops will grow. And many, many people live as if God did not exist.

  9. Legisperitus says:


    When you tally up the staggering improbability that all these things could have happened at random (also factoring in the improbability of the whole universe’s coming into existence at all, the improbability of living cells forming by themselves, and many others), it still doesn’t faze the atheists. The fact that all this occurred is, to them, simply proof that many staggeringly improbable things do happen at random.

  10. Random Friar says:

    I’m sorry, Legisperitus, were you calling me? My ears were burning.

  11. Legisperitus says:

    My apologies, Friar, I’ll have to be more careful.

  12. John V says:

    If you read through the Explanation and click on the
    full resolution mosaic
    link, you can really zoom in.

    Tony Layne: Did you know you can see images of the Apollo landing sites taken from the orbiter at the LROC web site ? Lots of other amazing pictures there too.

  13. irishgirl says:

    Yes, this is very cool! What a neat picture of the moon!
    I saw a beautiful view of the crescent moon with the planet Venus outside my window a couple of nights ago. Whenever I see the crescent phase, I always call it ‘The Immaculate Conception Moon’ (re: pictures by artists such as Murillo with the crescent moon under Our Lady’s feet).

  14. scaron says:

    Actually, its not strictly true that we only see half the moon’s surface from earth – we actually see a great deal more than that because of a neat trick of orbital mechanics known as libration. The moon does not move in a strictly circular orbit around the earth, but in an ellipse (this is why some tides are higher than others). As it moves around the ellipse, from the view of earth its orbit “speeds up” in some places, allowing us to see “around the edge” of the lunar ball. Also, the moon does not orbit in the same plane as the earth’s equator (if it did, there would be solar eclipses on every new moon and lunar eclipses for every full moon – but only for people living on the equator). So usually the moon is “higher” or “lower” than the earth’s equator, allowing us to look “over” or “under” the edge to the back side. This video -> shows this pretty well. Instead of just 50% of the moon’s surface, we actually see almost 60% from earth.

  15. JohnE says:

    I’m glad you raised the question about rotation Venerator because I was feeling pretty stupid when my 1st-grader’s class was studying the Moon. If I was the Earth and held the Moon’s axis out from me there is no rotation of the moon on its axis since the same side always faces Earth. However, if I hold the Moon’s axis and stand outside the Moon’s orbit then it becomes more obvious that the Moon truly is rotating on its axis. And if the orbit gradually became smaller and smaller until the Moon was at the center of the orbit (the Earth getting out of the way of course), then it would become more obvious that the Moon truly is spinning on its axis.

  16. Tony asked for a glimpse of the lunar landers. Shots of them have been taken from lunar reconnaissance satellites (LRO in this case). Here is the URL:

    Also, one way to think of the tidally locked moon that shows us more-or- less always the same face is to think of a boat on the ocean and we are at the bottom of the sea. The forces (and moments) acting on the boat tend to keep the boat upright. We at the bottom of the sea would only see the bottom of the boat as it floats in the ocean. Likewise, the moon floats, if you will, in a sea of gravitational forces (and moments) that tend to keep one side facing us at all times.

  17. “tidal”, is just a bit more wonderful than simply the moon pulling on our oceans; but even just at that, the tides flow on Earth because the Moon pulls most on the oceans facing it, least on the oceans facing away, and only sideways on the bits of Earth and ocean seeing moonset and moonrise; but the “tidal locking” described is actually how the Earth pulls most on the bit of Moon facing Earth, and least on the bits facing away. The net effect is that the Moon gets stretched out (very slightly) along the direction between Earth and Moon. Now, if the Moon weren’t locked, that stretch would be changing its direction all the time, which would heat the Moon slightly by friction, and that energy would tend to glow away into space… kinda weird really.

    The same effect hasn’t yet locked the Earth to the Sun (or the Moon) in part because the Earth is still runny enough that tidal heating doesn’t drain away that much kinetic energy (and the water, of course, is even runnier); and the Earth is still runny enough because there’s just enough trace Uranium and other slow radioisotopes in the mostly-silicate mantle to keep it melting hot! Something to think about. Geothermal energy is nuclear! And it keeps the Earth turning, without which we couldn’t live!

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