Scientists Confirm Existence of Moon

Bit of old news here — well, the existence of the Moon is extremely old news, but even this new result is slightly non-new. But it was new to me.

Ice Cube is a wondrously inventive way of looking at the universe. Sitting at the South Pole, the facility itself consists of strings of basketball-sized detectors reaching over two kilometers deep into the Antarctic ice. Its purpose is to detect neutrinos, which it does when a neutrino interacts with the ice to create a charged lepton (electron, muon, or tau), which in turn splashes Cherenkov radiation into the detectors. The eventual hope is to pinpoint very high-energy neutrinos coming from specific astrophysical sources.

For this purpose, it’s the muon-creating neutrinos that are your best bet; electrons scatter multiple times in the ice, while taus decay too quickly, while muons give you a nice straight line. Sadly there is a heavy background of muons that have nothing to do with neutrinos, just from cosmic rays hitting the atmosphere. Happily most of these can be dealt with by using the Earth as a shield — the best candidate neutrino events are those that hit Ice Cube by coming up through the Earth, not down from the sky.

It’s important in this game to make sure your detector is really “pointing” where you think it is. (Ice Cube doesn’t move, of course; the detectors find tracks in the ice, from which a direction is reconstructed.) So it would be nice to have a source of muons to check against. Sadly, there is no such source in the sky. Happily, there is an anti-source — the shadow of the Moon.

Cosmic rays rain down on the Earth, creating muons as they hit the atmosphere, but we expect a deficit of cosmic rays in the direction of the Moon, which gets in the way. And indeed, here is the map constructed by Ice Cube of the muon flux in the vicinity of the Moon’s position in the sky.


There it is! I can definitely make out the Moon.

Really this is a cosmic-ray eclipse, I suppose. We can also detect the Moon in gamma rays, and the Sun in neutrinos. It’s exciting to be living at a time when technological progress is helping us overcome the relative poverty of our biological senses.

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23 Responses to Scientists Confirm Existence of Moon

  1. Dan says:

    Boy, you’ll only see that once in a blue moon.

  2. Paulino says:

    A muon-less moon or when absence is evidence of presence.

  3. Jason Dick says:

    So, this is the Moon as viewed through the Earth? 🙂

  4. Pingback: Imaging the moon with muons. | Gordon's shares

  5. Ed Yong says:

    THAT’S NO MOON! It’s a spa… oh wait, it’s the Moon. My bad.

  6. rolandc says:

    if you were serious for a minit you would notice the color scheme and that the meaning of the color blue according to my caca reader oooops sowwy chakra reader … ahhh never mind … like santee close would say hohohohohoh could not keep it up till the end … anyhoo that coulda been a contender … not a ‘grette’ joke but decent … ‘grette’ is how my guatemalan teacher from dublin says great … i like colors … so sue me loretta …

  7. Carlos says:

    That’s no moon!

  8. On the lighter side: had Einstein known this, perhaps he would have rephrased his question, “Do you really think the moon isn’t there if you aren’t looking at it?”

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  10. rob says:

    einstein knew it

  11. tony says:

    Absence makes the muon grow fonder.

  12. Ken Kukec says:

    Do we have a definitive answer yet regarding the effect of gamma rays on man-in-the-moon marigolds? (Bears noting that the Pulitzer-prize winning playwright, Paul Zindel, was a science teacher before he took up Tennessee Williams-style drama.)

  13. Ken Kukec says:

    As to your final link, to your earlier post about the moon’s “pale fire” — no love for the meta-fiction posing as a footnote-packed poem by a Russian émigré (and S.J. Gould praised) lepidopterist?

  14. Platohagel says:


    It was important to me that clarification be looked at here as to how we see the moon in relation to what is transmitted “through the moon?” Use of IceCube. Do I have that right?

    We report on the observation of a significant deficit of cosmic rays from the direction of the Moon with the IceCube detector.Observation of the cosmic-ray shadow of the Moon with IceCube


    The Moon’s cosmic ray shadow, as seen in secondary muons generated by cosmic rays in the atmosphere, and detected 700 meters below ground, at the Soudan II detector.

    Looking at magma flows in volcanoes, or, even in transmitting to Gran Sasso, muon detection has become very useful tool.


  15. Chris says:

    I can see the headlines in the media now. “Scientists build neutrino telescope in Antarctica to confirm existence of the Moon.”

  16. rolandc says:

    please help with this one .. i was listening to the other ‘you’ on the tube -he is almost as great as you …9.99999 to your 10, larry krauss- and i am doing much better with the both of you ‘splaining’ physics … but i am stuck at the big whammo … it is a fact you say and was calculated as being a fact that the big bang ‘size’ was about ‘this big’ as you put it -1 cm. sq- … when it exploded or ‘banged’ how could it go in all directions -like from the center of a sphere outward- is this known?… my thoughts are where was the ‘impulse’, the small alteration/change in its smoothness state to make it go ‘boom’ … and disperse all the concentrating of thingies in the universe … if there is a ‘point’ , that point must have been pushing on/against ‘something to get ‘out towards’ all points of said sphere … i understand -i think- a vacuum where one needs impulse/energy to change location … but energy must react/push on something to ‘move’ … hope you can read this attempt at a question but i am not a surgeon … hahahaha get it … if not i’ll ‘splain to you when you answer … tanx a ‘googlion’ i am as free a man can be without knowing everything but an inquiring ‘mind’ wants to know … or a non-mind if you prefer … a consciousness in need of a knowledge fix …

  17. rolandc says:

    further thought on the question .. instead of trying to figure out the big bang why don’t they try a little bang … not particle accelerator little big bang but just a plain explosion of ‘nothing’ -almost nothing, the explosive whatever is used- will be real .. am sure it is feasible …

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  19. This is awesome on so many levels for me.I never even knew this experiment was going on, and that they just used it to show that the Moon blocks muons is simple yet so awesome. Go science 🙂

  20. Shantanu says:

    Christian, this is an old idea, proposed in 50s. This has been observed in a whole bunch of cosmic ray/neutrino underground experiments.
    See for example the following paper (which I am familiar with it)
    but there are many other references before this also

  21. Yeh I know about underground Neutrino experiemnts,but didnt realise they had done this. Suppose I always forget that some things are easy to do with the infrastructure in place. Thanks for the link to the paper.

  22. Anton Szautner says:

    That would be an extremely partial eclipse. The term “shadow” used by the IceCube folks isn’t very precise either. It is a silhouette of Luna against the cosmic ray background.