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How Astrophysicists Hope To Turn the Entire Moon Into a Cosmic Ray Detector
KentuckyFC writes One of the great mysteries in astrophysics surrounds the origin of ultra-high energy cosmic rays, which can have energies of 10^20 electron volts and beyond. To put that in context, that's a single proton with the same energy as a baseball flying at 100 kilometers per hour. Nobody knows where ultra-high energy cosmic rays come from or how they get their enormous energies. That's largely because they are so rare--physicists detect them on Earth at a rate of less than one particle per square kilometer per century. So astronomers have come up with a plan to see vastly more ultra high energy cosmic rays by using the Moon as a giant cosmic ray detector. When these particles hit the lunar surface, they generate brief bursts of radio waves that a highly sensitive radio telescope can pick up. No radio telescope on Earth is currently capable of this but astronomers are about to start work on a new one that will be able to pick up these signals for the first time. That should help them finally tease apart the origins of these most energetic particles in the Universe .
This seems not very much. How do we know of them at all?
"That's no moon..."
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Your mom is a visible light detector every time anyone looks at her.
Put differently, the moon is not being turned into a detector of anything, but "astronomers are building a telescope" is not a very catchy headline.
If the baseball analogy is accurate, the impact of such a ray should cause something more than just a burst of radio waves. Why don't we see evidence of inexplicable pockmarks on the earth's surface? Or do we? 1 per km2 per centry is a lot when you have such a large surface area like the Earth. Heck, we should have reports of people being stricken down in broad daylight from time to time.
Put my fist through my alarm clock with its ding-dong death inside my ear. - The Blackjacks.
Humanity's cross section is about 2000 km^2, so we should expect about 20 hits per year on people.
Describing a baseball's speed in kilometers per hour feels like mixing systems of measurement.
You people and your slight differences disgust me! - Prof. Farnsworth
The earth's surface area is pretty large, but from any given point on the earth, you can only see a small bit. And it's probably cheaper to aim a detector at the moon than it is to put one in orbit and look at the earth.
While what you say is true, you fail to consider the number of protons in a baseball.
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It's about the detection area. You can't pave the earth with detectors (half) the surface area of the moon. Or well - maybe you can but that would cost a lot more than a single indirect detector using the moons surface.
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