Re: OT: Astronomy Picture of the Day
 

Re: OT: Astronomy Picture of the Day
 

I saved this last one. I collect similar images (as opposed to artist's conceptions like the previous one). I have other images of the planet, like those from the Hubbel telescope, but none of this scope and resolution.

Re: OT: Astronomy Picture of the Day
 

Re: OT: Astronomy Picture of the Day
 

Re: OT: Astronomy Picture of the Day
 

Been looking at this picture of Mars, and eating ham sandwiches, so here's what I came up with:

That big trench is where a tan meteor plowed into Mars, creating an Extinction Level Event to a normally dark colored world. The craters indicate that it happened a long time ago--say a bajillion years? K, so I've never really believed there's such a thing as a 'stable' orbit. Things go sailing off, or they fall back down. And all the planets are basically burped out by the Sun every so often. So...a bajillion years ago Mars was where Earth is today, and had a thriving civilization on it. And in another bajillion, it will be Venus' turn. We should send archeology excavator robots to Mars.

So um, guess I'm just saying, don't eat ham sandwiches after midnight.

Re: OT: Astronomy Picture of the Day
 

From http://antwrp.gsfc.nasa.gov/apod/ap060730.html ,

"The origin of the Valles Marineris remains unknown, although a leading hypothesis holds that it started as a crack billions of years ago as the planet cooled."

Planetary orbits seem to be more stable than stars themselves.

I don't think planets are likely burped out of stars, but are probably formed back when the star itself was formed.

However, the star's behavior can change, and things can smash into planets and change their environments (or, their human-stupid inhabitants can destroy their environments themselves...).

PvK

Re: OT: Astronomy Picture of the Day
 

These guys suggest orbital "changes" are the reason that gas giants have been found in very close proximity to their host stars.

"we might expect any planetary system to follow the general plan of our own, with small, dense, rocky worlds occupying orbits close to the central star and large, low-density, gassy worlds orbiting at much greater distances. However, the majority of the first batch of extrasolar planets to be confirmed do not conform at all to this scheme. Planets with masses even greater than that of Jupiter have been found in near-circular orbits within 2 astronomical units (and, in some cases, within 0.1 AU) of their host stars."

Perhaps the concept of changing from one stable position to another isn't necessary. One can just envision a decaying orbit.

Perhaps Global Warming is just orbital decay.

Re: OT: Astronomy Picture of the Day
 

I think the astronomers would notice that.

Re: OT: Astronomy Picture of the Day
 

I think it's more likely that large gas giants in close orbits have been discovered so far due mostly to the methods that we currently have to use to detect extra-solar planets. The most fruitful efforts detect minor gravitational perturbations that the planet induces in the parent star in order to detect the planets. This method will inherently favor discovery of large planets that are close in. Planets that are smaller or that are farther out will induce much smaller gravitational perturbations within the parent star, so will be much harder to detect with our current instruments...though hopefully the proposed TPF (Terrestrial Planet Finder) array will change that if it ever gets off the ground.

Re: OT: Astronomy Picture of the Day
 

A humorous method of interstellar communication I've had pop up in my mind now and again involves very good telescopes...And very large signs.

"We are sorry to hear,"
"About your nuclear winter,"
"We hope the plans we sent"
"You, cool the planet off."
"Burma Shave."