How Astrophysicists Hope To Turn the Entire Moon Into a Cosmic Ray Detector 74
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 .
less than one particle per square kilometer/100yrs (Score:3)
This seems not very much. How do we know of them at all?
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By being really clever! My father was a cosmic ray physicist and had a cosmic ray lab on top of Mount Evans (14000+ feet) in Colorado to detect these critters. I honestly don't know if he ever "captured" one, but he was awarded a Gugenheim fellowship to continue his research world-wide, and a number of his graduate students who suffered a winter on top of the mountain got their PhD's continuing the research.
Re:less than one particle per square kilometer/100 (Score:5, Insightful)
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My first question when I saw this was how much time on the sky you'll get.
Is a few hundred hours/year statistically significant.
Are you likely to get much more than that considering all the competing survey proposals ?
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You're an idiot commenting about a subject you know nothing about.
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Can too.
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This seems not very much. How do we know of them at all?
Because there are a lot of square kilometers out there... especially when the blurb doesn't actually define what the surface area of observation is!
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We detect the particle spray that they start when they hit the upper atmosphere.
Finally! (Score:3, Funny)
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Um. Yeah. Yeah, it really is a moon.
Just because TFS and a line from Star Wars both have the word 'moon' in them, does not mean that this was a clever time to quote the movie.
By that logic (Score:5, Insightful)
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.
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Oh yeah?? Well your GRANDMA is a visible light detector every time anyone looks at her!
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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.
But it's not like they are just bouncing the high energy particles off the moon and then detecting them, they are letting the particles hit the moon, then are picking up the secondary effects.
If you want a "your mom" analogy, I think a better analogy would be if they hoisted your mom by crane and dangled her in front of a microwave antenna to make her a "microwave detector" - scientists on the ground will measure her temperature with an IR camera, he she heats up, then there's microwave radiation.
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he she
Hey, that's the guy's mom you're talking about!
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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.
That's no moom...
Wait. What?
Yo momma's so fat, astronomers can use her to detect cosmic rays.
There we go. I knew there was a kitschy joke in there somewhere.
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While what you say is true, you fail to consider the number of protons in a baseball.
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While what you say is true, you fail to consider the number of protons in a baseball.
Sure, but if you don't live in a country where baseball is commonly played then it is hard to have a frame of reference for how large a baseball is. Conversely if you do live in a country where baseball is commonly played then you likely don't use the metric system in daily life.
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Fine a baseball thrown by a varsity high school player
Is that a European school or a South African school?
(well, somebody had to ask!)
SubjectsInCommentsAreStupid (Score:2)
mini-explosion? (Score:3)
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.
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Re:mini-explosion? (Score:4, Insightful)
"Your gonna put an eye out" (Score:2)
So an astronaut could be just working away in space and suddenly Booof! they are gob-smacked by one of these and lose an eye?
I suppose a pebble-sized meteor out of nowhere is also a danger to them.
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The total surface area of all astronauts is far less than 1 km squared so on average one should be hit by one once in far more than a century. We haven't been in space for a century.
Pebble sized meteors at far lower speed but with far higher impact energy are far more common.
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No, not really.
1 per km^2 per century is one hit every six seconds for a planet this size.
For the face of the moon we can see, it'd be about one hit every three minutes...
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What are the symptoms? (Score:2, Insightful)
Humanity's cross section is about 2000 km^2, so we should expect about 20 hits per year on people.
Re: What are the symptoms? (Score:1)
Well there are a lot of things I could write about cosmic rays interacting in the upper atmosphere making it improbable to be hit by a cosmic ray proton rather than it's (usually) less dangerous products. But the important thing is actually is that even if you do get hit by just one, what's it gonna do? Probably just interact with another particle in you, resulting in both exploding into other particles which carry away the energy, some of which may interact again within your body, but most not. My point is
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running for Congress
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Doesn't matter. The particles hits the upper atmosphere. (it either hits an atom head on, desintegrating it (low chance), or the magnetic field interactions with a lot of atoms drain energy from it to the other atoms (that's more likely)). In both cases a waterfall of lower energy particles showers down. These particles are detected with our detectors. Not the particles themselves.
In other words: unless you are unshielded in the upper atmosphere you are not going to be hit by one. Even in that case I would
How? (Score:1)
hat should help them finally tease apart the origins
How do you "tease" something apart?
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tease:
gently pull or comb (something tangled, especially wool or hair) into separate strands.
Waiting for the inevitabl (Score:1)
I'm just wondering how long before the anti-science crowd (or the news media, in order to drum-up readership) starts presenting this as some sort of dire threat, like they did with the CERN Large Hadron Collider. That had to be stopped because it might create black holes that would eat up the entire Earth.
How will this new development be presented? "It's focusing all the cosmic rays bouncing off the moon down to the Earth; it could boil us alive!"
Whatever they come up with, I hope they work quickly though;
100 kph? (Score:4, Funny)
Describing a baseball's speed in kilometers per hour feels like mixing systems of measurement.
Re:100 kph? (Score:4, Funny)
you are correct, the hour is not a SI metric unit of measurement
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lagrange point location (Score:1)
Put the new telescope in one of the stable earth-moon lagrange points so that the moon will always be visible. The one on the other side would even be quieter! That will be $0.02, please. Zaza
Are we finally going to (Score:1)