odd, about all the planets here.....?

Question

doing a little Googling, I ran across this site....the table on that page explains the sidereal and synodic periods.... it has confused me greatly....but... what I noticed was that the inner planets' keep the same face to the sun, as the moon does to us, both Earth and Mars have nearly the same day length, and then you hit the gas planets and the cloud movement around them goes crazy fast, then get us to the outlying planets and they're crooked and spinning like wild!.... what's bothering me most is why the change from spinning to nearly NO spin the closer you get to the Sun?... and what good reason is there, then for both Earth and Mars to be on basically the same period.....

would the Earth spin be connected to the hit that brought us the moon?... should Mars be turning faster?.... and why DOESN"T the moon revolve...is it it's proximity to Earth?... and that's what's up with the inner planets?....

I thought it strange that there's two of each, too...thanks for ideas....

I guess adding the site and the table would have been helpful?....

http://www.cseligman.com/text/sky/rotationvsday.htm

thank you , about the inner planets... ok.. they're just very SLOW 'days'...yes?.. but all sides of the planets eventually turn toward the sun, right?....NOT like the Moon/Earth set up....??

Answer 1

The reason is that the planets closer to the sun are subject to a much stronger gravitational attraction from the sun, which causes them to lose rotational speed. The planets further out have much less gravitational drag from the sun, and Jupiter, Saturn, Uranus and Neptune are much larger than the inner planets, in any case. The gravitational drag from the sun is causing the earth's rotation to slow gradually, maybe a second or so a century.

For the same reason, the moon's rotation has been slowed by the earth, to the extent that its rotational speed is the same as its orbit speed; hence it always shows us the one face.

An interesting fact about the moon is, unlike any other moon in the solar system, the gravitational effect acting on it from the sun is actually stronger than the gravitational attraction from the earth (otherwise, it would be a lot closer). The earth and moon, in this regard, are like a double planet, rather than planet and satellite.

Answer 2

Mercury does not keep the same face to the sun. The mercury year is 87.97 Earth days, while the Mercury day is 176 Earth days (two Mercury years). Mercury is in 3:2 spin–orbit resonance with the Sun, meaning that it rotates 3 times for every 2 orbits around the sun. After billions of years, Mercury's spin has become tidally locked to the Sun, because the Sun's gravity is so strong and Mercury is so close to the Sun.

Synodic period is relative to the Earth -- the time it takes for Mercury to reappear in the same place in the sky. It's a combination of the Mercury orbit period and the Earth orbit period.

Also Venus does not keep the same face to the Sun. A day on Venus lasts about 116.75 Earth days; with the sun rising in the West, and setting in the East!

The Mars day and Earth day being so close is mostly just coincidence.

The moon keeps the same face to the Earth because it is tidally locked to the Earth, like Mercury is to the Sun; except that the Moon is in 1 1:1 lock, while Mercury is in a 3:2 lock.

Answer 3

To answer part of your question, the moon is tidally locked to the earth. The earth's gravity slowed the moon down over time. Eventually, the moon will do the same to the earth, but it will take much longer.

And the inner planet are NOT tidally locked to the sun.

Answer 4

sorry.. i didnt understand the question. =(
Im no good at astronomy and space. :0)