*What Do You Know?

About planets...

My "What Do You Know?" posts have some facts I find interesting/obscure/whatever about a given topic...and you are encouraged to debate or add to them. I never claim to know it all. ;-) So click to continue and leave a comment.

The Big Bang theory basically states that about 15 billion years ago there was a cataclysmic fireball, and a few billionths of a second after that was the first matter. When the universe cooled enough, more familiar particles formed...the neutrons, electrons, and protons that make up everyday matter. Gradually these particles formed atoms--mainly helium and hydrogen, which collapsed under the influence of gravity and created stars and planets.

The Big Crunch theory is based on the finding that gravity is slowing the universe's expansion. The pull of gravity may cause the expansion to stop and reverse back on itself...slowly at first, but then speeding up until the last moment when all matter will coexist as a single point.

Mercury has wide variations of hot and cold temperatures because it has virtually no atmosphere to protect it. The sunny side of the planet is as much as 750 degrees F, while the dark side drops to minus 330 degrees F.

Venus is the hottest planet in our solar system...approximately 860 degrees F regardless of time of day. This is because of it's thick atmosphere of carbon dioxide...the Sun's heat warms the planet, but the heat cannot escape into space.

Earth is the only planet in the solar system with liquid water. Our atmosphere is so thin that if Earth were the size of an apple, the atmosphere would be as thick as the peel.

The favored theory of the Moon's creation is that about 4.5 billion years ago a giant object struck Earth and produced a cloud of rocky debris that eventually collected itself together to form the Moon.

Mars has four seasons and used to have water running on its surface. Now frozen water can be found there. Olympus Mons is an apparently dormant volcano on Mars which is larger than any mountain we have here.

Jupiter has more mass than the other planets put together. Its makeup (75% hydrogen and 24% helium) is similar to the Sun, and its gravitational pull controls 16 moons as well as assorted comets and asteroids that come too close. For all its size, Jupiter has a quick rotation period...less than 10 hours, which turns its cloud features into east-west stripes.

Saturn's rings are no more than a few hundred yards thick, but can be seen through a backyard telescope. Scientists think the rings will disappear eventually as the particles fall into Saturn.

Uranus is tilted almost completely to its side (by comparison, Earth has a 23 degree tilt). One theory is that an object the size of Earth crashed into it and more or less knocked it over.

Neptune is believed to be mostly frozen water, but the reason it is the blue planet is due to a layer of methane in the top of its atmosphere. It also has the only large moon that revolves backward...possibly due to a collision with another, long-gone moon.

Pluto was named after the Roman god of the underworld and has a moon that is about half its size. The moon, Charon, is only 12,100 miles from Pluto (our Moon is 239,000 miles away), and orbits the planet every 6.4 days.

Posted by Jennifer at November 6, 2003 10:46 AM

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