Comments on: More Mercury!

By: Steve Dutch

Steve Dutch — Tue, 29 Jul 2008 02:07:13 +0000

The near stationary appearance of the sun at Mercury’s perihelion is no accident. Mercury’s aphelion is 1.5 times its perihelion distance, and since tidal forces are inversely proportional to the cube of distance, the solar tides at perihelion are 3.5 times larger than at aphelion. So Mercury’s rotation is locked to the sun, but locked to the sun at perihelion, since the tidal forces are so much stronger then. We used to think Mercury was locked to the sun like the Moon is locked to the earth, but it’s a more complex kind of lock.

By: Steve Cooperman

Steve Cooperman — Sat, 19 Jan 2008 10:19:24 +0000

With the pictures of Mercury now coming in, I find it striking (no pun intended) that many of the craters have central rings or craters — many more than our Moon has.

I haven’t heard any comments about it yet, but they seem similar to the morphology of the craters on Ganymede (one of the moons of Jupiter):
http://img375.imageshack.us/img375/9899/ganmogac4gs.jpg

Here’s a picture of Mercury:
http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/EW0108829708G.4release.jpg

Now, Ganymede is rock and ice, but I’m not implying that Mercury is. But Ganymede may have a large rocky core topped by a rock-ice layer that the craters are in (although way more ice than the inner Galilean moons), and Mercury certainly has a large core (although made of iron). I’m suggesting that the central crater/ring is a seismic “bounce” in some way off the core from the impact.

On the Moon, craters that are small don’t have central peaks. As the craters get larger, they develop central peaks. For even larger craters, you can get double or more complicated central peaks and the largest have central rings. (Mercury has lots of craters with central peaks, too — I’m just suggesting that Mercury has MORE craters with central craters than it “should have” and wondering about the reason.) But the Moon also has a very small core.

Mercury’s surface is also saturated with craters, like Callisto’s — another moon of Jupiter:
http://astrored.org/astrofotos/albums/Sistema_Solar/Jupiter/callisto.jpg.html

Look how many craters are there, and most seem to have central craters! Callisto is thought to have an even larger core than Ganymede, but the saturation of large numbers of craters indicates a very OLD surface (nothing’s come by to erase the craters over the age of the Solar System.

This stuff is amazing to me . . .

BTW, for those interested, here’s a website that predicts sizes of craters on the Earth from various impacts:
http://www.lpl.arizona.edu/impacteffects/

— Steve >>>>

By: Ken B

Ken B — Fri, 18 Jan 2008 18:05:52 +0000

Clearly, it’s Kang (or Kodos) in that image.

http://www.hvcomputer.com/temp/mercury.html

By: Sally

Sally — Thu, 17 Jan 2008 21:57:31 +0000

Dude, you really should learn about geology. I think you’d dig it!

By: Jack Hagerty

Jack Hagerty — Thu, 17 Jan 2008 21:21:39 +0000

Quiet Desperation says: ” ‘— I’m guessing that in the future, Mercury will be home to a huge metal mining operation.’

In the Transmetropolitan graphic novels, it’s mentioned that Earth is powered by the energy transmitted from Mercury, which has been completely covered by solar panels.”

Don’t forget “Runaround”, one of Asimov’s robot stories.

- Jack

By: Anthony

Anthony — Thu, 17 Jan 2008 21:10:31 +0000

Digging into Mercury, unless at the poles, won’t ever make it cool enough to survive. Underground will simply average out the sunlight, making it hot year-round.

By: Sabrina

Sabrina — Thu, 17 Jan 2008 16:55:02 +0000

Connect the dots la la la la Connect the dots la la la la

http://www.moostangproductions.com/temp/other.gif