Bye Bye Moon...

Do you have the simplest of telescopes? lol. Maybe I'll check it out on the live stream or something. Although I don't think I should pull a second all nighter in a row. My body is already angry enough at me.

I'm awake all night anyway (just a nocturnal person by nature - and luckily my schedule allows it), so that would be neat to see. Unfortunately I don't have ANY telescope, simple or otherwise... not usually much to see around here, between the fog and city lights. Oh well. :(

I wonder what the results were?

http://news.yahoo.com/s/ap/20091009/...shoot_the_moon

Quote:

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Originally Posted by Patrick Long

7:30am EDT 4:30am PDT Nasa is launching two rockets (LCROSS- Lunar CRator Observation and Sensing Satellite) into the moon in two different stages.

It will be visible from the most simple telescope as it will throw a cloud of dust 6.2 miles into the sky...


Check it out...I already got my alarm set!


http://www.nasa.gov/mission_pages/LC...ain/index.html

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ill still be sleep and its cloudy here anyway i trust youll take pics and post them right?:gj:

Apparently, no 6 mile plume. Just like there wasn't 20-30 feet of dust on the moon as scientist thought before the firstmoon landing. Did ever wonder why the moon lander had really long legs with giant snowshoe feet?

They suspect they hit a "dry" crater. Sucks for all the observatories who packed their stadiums full of people to watch....NOTHING.


I know I was bummed to stay up til 4:30

Quote:

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Originally Posted by Patrick Long

Not what I read online, OR heard on the news.

It says that the plume will be visible from the SIMPLEST of scopes.

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Actually, it says 10 to 12 inches in the NASA link given in the OP.

But let's do the math.... The plume was supposed to be about 6 miles tall. The distance to the moon is about 238857 miles.

angle on the sky = 6 / 238857 miles = 2.5 x 10^-5

This means that the angular size of the plume is 2.5 x 10^-5 radians (or, in astronomical terms, 5.2 arcseconds). We need an instrument with an angular resolution of at least 5.2 arcsec.

The resolution of a telescope, in simple terms, is wavelength / diameter of aperture. Fully dark-adapted, a human eye has an aperture of 8 mm. A 12-inch telescope is 305 mm. Let's use the peak wavelength of the sun's light since that's what the moon is reflecting: ~500 nm = 5 x 10^-4 mm

Resolution of human eye = 5 x 10^-4 / 8 = 6.25 x 10^-5 radians.

Resolution of 12-inch telescope: 5 x 10^-4 / 305 = 1.6 x 10^-6 radians.

So just in terms of resolution, we cannot hope to see a six-mile plume on the moon, but a 12-inch telescope can see it plain as day.

However, the problem isn't just resolution. The moon is insanely bright right now--a day shy of third quarter. A tiny, diffuse plume of dust will more than likely be rendered invisible to the human eye (and small telescopes) due to the overwhelming light from the moon. We can see how light from the moon washes out faint objects by looking at pictures from the Apollo moon walks. Note that there are no stars in the sky! This is because the moon's surface was so bright, the astronauts had to be sure to not over-expose the pictures! :)