Astronomy Picture of the Day 9-14-02

NASA ^ | 9-14-02 | Robert Nemiroff and Jerry Bonnell

[petuniasevan]

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2002 September 14

X-Ray Moon
Credit: J. Schmitt et al., ROSAT Mission, MPE, ESA

Explanation: This x-ray image of the Moon was made by the orbiting ROSAT (Röntgensatellit) Observatory in 1990. In this digital picture, pixel brightness corresponds to x-ray intensity. Consider the image in three parts: the bright hemisphere of the x-ray moon, the darker half of the moon, and the x-ray sky background. The bright lunar hemisphere shines in x-rays because it scatters x-rays emitted by the sun. The background sky has an x-ray glow in part due to the myriad of distant, powerful active galaxies, unresolved in the ROSAT picture but recently detected in Chandra Observatory x-ray images. But why isn't the dark half of the moon completely dark? It's true that the dark lunar face is in shadow and so is shielded from direct solar x-rays. Still, the few x-ray photons which seem to come from the moon's dark half are currently thought to be caused by energetic particles in the solar wind bombarding the lunar surface.

[petuniasevan]

Astronomy Fun Fact:

We've come a long way in 12 years! This image was technologically advanced in 1990. Now the Chandra spacecraft sends back images that make this look like a cheap enlargement.

I've got to get this post done and go to bed. Felt lousy all day at work, and just checked my temp.
Errgghh! 100 F. Gotta work tomorrow too!

[petuniasevan]

[sleavelessinseattle]

Yo, P7 If you gots da contagion, drop me a note...I gots the 15th APOD if you needs da break! Get BETTER!;-D I am still squeamish about long term space travel until some sort of field can be generated to stop Xrays and Cosmic Rays hitting the crew...The stories of the astronauts on the space station "seeing" cosmic rays in the darkness originating from the sun sort a creeps me out, aright?

[BossyRoofer]

Great picture and explanation! Hope you feel better soon! Thanks for all your hard work. APOD is great!

[RightWhale]

The stories of the astronauts on the space station "seeing" cosmic rays in the darkness

Reports are they can be seen inside the eyeball. Kind of a bubble chamber, a flash of light inside the eye when it is completely dark.

[sleavelessinseattle]

One chap even tried holding a lead battery next to his head between him and the sun(source of the solar flare that was bombarding the ISS with Xrays). No success, though. I'd rather NOT have my melon allow me to become a direct observer of nuclear particle reactions...Lets leave that to CERN!

[2Trievers]

Feel better 'tunia! Maybe we should stop all this space exploration and work on the commom cold? &;-)

[sleavelessinseattle]

Without occasional challenges to the immune system we would be wide open to diseases that would normally not be serious!

[petuniasevan]

Thanks, but that doesn't help a lot. :)

I'll be okay to do the APOD.

I got 11 hours' sleep (!) and feel a bit better.

[Imperialist]

"But why isn't the dark half of the moon completely dark?"

Could it be that the dark side of the moon is reflecting back what the Earth reflects onto the dark side of the moon?

[petuniasevan]

That's what it is. It's called "Earthshine".