You are here:

Astronomy/my grandma has a question for you

Advertisement

Expert: - 5/3/2009


Question
why do the planets orbit the earth on a parallel line like they all go across if you where to draw a line they would all be on the same line why

Answer
This is explained by the Solar Nebula theory of the origin of the Solar System. The planets formed out of a cloud of gas and dust rotating around the forming Sun. The contraction of such a cloud (due to the Sun's gravitational pull) causes it to form a flattened disk centered on its axis of rotation (and the Sun). Once that happens, any objects which form in the disk will move around the Sun in the same direction and plane that the disk was in. So as long as the planets built up from such a disk, they would all follow the same 'line' around the sky as seen from the Sun, or from any other object in the plane of the disk, such as the Earth.

Astronomy

All Answers

Answers by Expert:

Ask Experts

Volunteer

Courtney Seligman

Expertise

I can answer almost any question about astronomy and related sciences, such as physics and geology. I will not answer questions about astrology and similar pseudo-scientific rubbish.

Experience

I have been a professor of astronomy for over 40 years, and am working on an online text/encyclopedia of astronomy.

Publications
Astronomical Journal, Publications of the Astronomical Society of the Pacific (too long ago to be really relevant, but you could search for Courtney Seligman on Google Scholar)

Education/Credentials
I received a BA in astronomy and physics and a MA in astronomy, both from UCLA. I was working on my doctoral dissertation when I started teaching, and discovered that I preferred teaching to research.

Awards and Honors
(too long ago to be relevant, but Phi Beta Kappa and Sigma Xi still keep trying to get me to become a paying member)

©2012 About.com, a part of The New York Times Company. All rights reserved.