In our solar system, do the planets line up on a certain plane, i.e., on the equatorial latitude of the sun?

Question

The planets are in orbit, if I could shot a hypothetical bullet through the middle of Mercury would it pass through the rest of the planets assuming that they were lined up one behind the other (like an eclipse) and also assuming the bullet could penetrate a planet.

Answer 1

The orbits of the planets are all more or less in the same plane (called the ecliptic and defined by the plane of the Earth's orbit). The ecliptic is inclined only 7 degrees from the plane of the Sun's equator.

As for why:

The orbits of the planets are coplanar because during the Solar System's formation, the planets formed out of a disk of dust which surrounded the Sun. Because that disk of dust was a disk, all in a plane, all of the planets formed in a plane as well.

Rings and disks are common in astronomy. When a cloud collapses, the conservation of angular momentum amplifies any initial tiny spin of the cloud. As the cloud spins faster and faster, it collapses into a disk, which is the maximal balance between gravitational collapse and centrifugal force created by rapid spin. The result is the coplanar planets, the thin disks of spiral galaxies, and the accretion disks around black holes.

Answer 2

The planets generally are in the same plane, not a straight line or the same path. The planets therefore appear in about the same arc in the sky, starting at the east horizon rising south upward and then down to the west horizon.

Answer 3

No, they don't line up that close. Close, but not that close. If you picked the orbits of just two planets, like Mercury and Venus, and draw all the possible lines from Mercury's orbit to Venus' orbit, then some of those lines would hit Earth's orbit. But when you continue those lines out, they would ALL miss Mars.

Think of it this way: if you were on the Earth, and you could see the orbits of Mercury and Venus as lines in the sky, then you would see those orbits appear to cross each other (actually, Mercury's is behind Venus'). So that means you could draw a line from a point on Mercury's orbit, to Venus', to Earth. BUT .. that line, continued in both directions, does NOT hit the orbit of any other planet. And at different times of the year, you could draw different lines, but none of them would hit Mars.

Answer 4

They line up, but not that well, the only one which was out of the plane was a certain ex-planet, who shall remain nameless. He was at about 7 degrees from the plane of the solar disk. It didn't help his cause, so now he is a minor planet, demoted and wandering aimlessly in the cold, dark void.


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Answer 5

You know, planetary alignments have been predicted for centuries and were interpreted as all kind of omens. But when science tries to measure it, it is never that well aligned.