Astronomy Picture of the Day 3-12-03

NASA ^ | 3-12-03 | 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.

2003 March 12

Lunar Farside from Apollo 11
Credit: Apollo 11 Crew, NASA

Explanation: The far side of the Moon is rough and filled with craters. By comparison, the near side of the Moon, the side we always see, is relatively smooth. Since the Moon is rotation locked to always point the same side toward Earth, humanity has only glimpsed the lunar farside recently -- last century. The light highlands of the far side are older than the dark Maria of the near side. A thinner crust on the near side that allowed for more dark lava flows is thought to be the cause of differences between the two sides. The cause for the crust thickness differences is still being researched, however. The large impact basin pictured above is Crater 308. It spans about 30 kilometers and was photographed by crew of Apollo 11 as they circled the Moon in 1969.

[petuniasevan]

We're way overdue in returning astronauts to the Moon. It's been over 30 years, NASA! What gives?

The radar signature of water ice was recently detected in some of the Moon's polar craters (bottoms in permanent shadow) by spacecraft Cloementine. The purposeful crash of Lunar Prospector, though, did not detect water ice so the jury's out. Here's the link:

Ice on the Moon

South Pole of the Moon from spacecraft Clementine

[petuniasevan]

[MozartLover]

bump

[MeekOneGOP]

Good mornin' ! Thanks. . .

[BossyRoofer]

Beautiful pictures! Great job APOD!

[RightWhale]

Here's a question for astronomy buffs: How many planets does the sun have?

[RightWhale]

Here's a hint:

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Having Pups Over Pluto And The Planetary Misfits Of The Kuipers

Ask any kid how many planets are in our solar system, and you'll get a firm answer: nine. But knock on a few doors in Berkeley's astronomy department, and you'll hear, amid the hemming and hawing, a whole range of numbers. Professor Gibor Basri, who plans soon to propose a formal definition of a planet to the international body that names astronomical objects, argues that there are at least 14 planets, and perhaps as many as 20. To the well-known list of nine he adds several large asteroids and more distant objects from the rocky swarm called the Kuiper Belt circling beyond the orbit of Neptune.

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Someday kids may be stumping their parents with planet names such as Vesta, Quaoar and Varuna, if not Ixion or Radamanthus. They'll be around for a while -- at least a few billion years -- so you might as well get used to them.