Posted on 04/29/2016 5:07:09 AM PDT by SunkenCiv
Explanation: If you could only see gamma-rays, photons with up to a billion or more times the energy of visible light, the Moon would be brighter than the Sun! That startling notion underlies this novel image of the Moon, based on data collected by the Fermi Gamma-ray Space Telescope's Large Area Telescope (LAT) instrument during its first seven years of operation (2008-2015). Fermi's gamma-ray vision doesn't distinguish details on the lunar surface, but a gamma-ray glow consistent with the Moon's size and position is clearly found at the center of the false color map. The brightest pixels correspond to the most significant detections of lunar gamma-rays. Why is the gamma-ray Moon so bright? High-energy charged particles streaming through the Solar System known as cosmic rays constantly bombard the lunar surface, unprotected by a magnetic field, generating the gamma-ray glow. Because the cosmic rays come from all sides, the gamma-ray Moon is always full and does not go through phases. The first gamma-ray image of the Moon was captured by the EGRET instrument onboard the Compton Gamma-ray Observatory, launched 25 years ago.
(Excerpt) Read more at 129.164.179.22 ...
[Image Credit: NASA, DOE, International Fermi LAT Collaboration]
How strong are those gamma rays?
That is an important question. It could make building a colony on the moon impossible, thereby shattering the dreams of millions of science fiction fans.
Gamma rays are the ones that damage DNA and cause cancer; at high doses, they are rapidly lethal.
Name a number that doesn't fit that description.
space now scares the hell out of me
so basically, the universe is a giant microwave oven, and we’re hotdogs
Everything about the universe, the solar system, the earth, etc. is scary. There are so many things that can kill you... this is why I try not to think about these things too much. It doesn’t help that I am also fascinated by these things.
There are existing caverns that would serve just fine, blocking the gamma rays.
That article is confusing. I get that the moon would look far “brighter” if we could see gamma radiation, but are they saying that it would be brighter than the visible-light version of the sun we currently see, or would it be brighter than the sun no matter what (because presumably the sun would also be pretty bright in the gamma spectrum)?
And that leads into another line of inquiry: Apropos the Asimov story “Nightfall”, how “dark” would the night sky appear to a life form that “saw” in the gamma spectrum?
Hmm.
I always imagined domes on the lunar surface, open to the starlight, where people could live and always look up to view the celestial scenery. In a cavern, they would be stuck looking at rock. Maybe shielded windows could give them a view.
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The Moon glows in the gamma ray spectrum because it’s reflective and has no mitigating atmosphere; the Sun does not glow in the gamma ray spectrum, because it doesn’t produce ‘em, and reflects nothing much.
Probably both.
“They could be entrances to a geologic wonderland,” says Mark Robinson of Arizona State University, principal investigator for the LRO camera. “We believe the giant holes are skylights that formed when the ceilings of underground lava tubes collapsed.”
http://science.nasa.gov/science-news/science-at-nasa/2010/12jul_rabbithole/
http://news.discovery.com/space/lunar-lava-tubes-could-host-underground-moon-cities-150402.htm
The moon surface and lack of magnetic field or atmosphere is very reflective. The sun being an active star just absorbs and recycles the energy.
Freekin gamma rays. They’re everywhere.
This lil bubble we live in IS the only ‘relatively’ safe place. Chalk and all.
This is really quite clear; I don't understand the confusion on the part of the other Freepers who are puzzling over this statement.
ANSWER:
The subordinate clause "...photons with up to a billion or more times the energy of visible light..." is really just an extra / unneeded explanation of what gamma rays are. So DELETE it! Sentence then reads:
If you could see only gamma-rays, the Moon [as viewed from the Earth] would be brighter than the Sun [as viewed from the Earth]!
NOTE: I've added the words "as viewed from the Earth" because I am assuming that, were both the Sun and the Moon placed at the same distance from the viewer, the Sun would still outshine the Moon - even in the gamma spectrum. This is the difference between the apparent magnitude of a celestial object (i.e., how it appears to a viewer stationed on Earth) and its absolute magnitude (i.e., its brightness at a set distance).
The meaning of this passage is then obvious: In the visible spectrum, the Sun has a greater apparent brightness (i.e., we here on Earth receive more visible photons from it) than the Moon, but in the gamma ray part of the spectrum, the Moon has a greater apparent brightness (i.e., we here on Earth receive more gamma photons from it) than the Sun (maybe only slightly brighter - the "billions or more times" refers to the more-energetic nature of a single gamma photon in comparison with a single photon of visible light).
The article does the reader a great disservice by not immediately explaining how / why a thermonuclear furnace like the Sun does not emit more gamma photos which reach Earth than the Moon.
Regards,
Pretty.
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