Hi! I was wondering if any of you guys know how often the 9 main planets are aliegned almost perfectly (within 20 degrees)

Short answer, not very often.

visit the B.A.'s page on planetary alignments for info and lots of links.

http://www.badastronomy.com/bad/misc/planets.html

Aligned within twenty degrees from the Sun?

I assume that since you've included the Earth. Of course, that means that Mercury and Venus will be on the other side of Earth from the rest of them.

The BA includes discussion about it in his book.

Thanks for ghe information but it didn't really help actually answer my question...anyone else have any ideas?

Well, Glutomoto's link is the BA's page, and the BA links to Brian Monson's conjunction analysis page. Brian lists ten dates in the last thousand years when Mars, Jupiter, Saturn, and the Sun would be within ten degrees of each other. Of course, that means Jupiter and Saturn were on the other side of the Sun from the Earth--which is why I wondered what you meant exactly.

When you include all planets, that makes the alignment a lot less likely, since Pluto and Neptune align only every 500 years--but they're within 20 degrees of each other for about fifty years each time. Uranus takes 84 years to go around the Sun, so a third of the time, it probably doesn't join them--Saturn will since it only takes thirty years to go around the Sun but there is no guarantee that it'll be there when Uranus is there.

Why do you ask, anyway?

Thanks for the info! I ask because my astrophysics club does a "question of the month" type thing and I havn't been able to find any other information this month. And plus all this stuff is really cool so why not talk to people who probably know a lot more about it? ^_^