Features of the Solar System: How can we deduce the origin and present state of the solar system? Until recently, all our observations of the Sun and planets have been made from the surface of the Earth. We see points of lights moving in the sky, but how can the information be translated into a vivid picture of a dynamic system?
Humans have studied the solar system for thousands of years, making observations and proposing models. Ancient scholars record the changing positions of the brightest planets, such as Venus and Jupiter. Applications of the telescope by Galileo led to the discovery of numerous new, faint objects, including several moons and other small bodies. Our present understanding of the solar system, therefore, represents the cumulative effect of centuries of observations.
As astronomers gather data on the solar system, they noticed several striking regularities the orbits of planets and the distribution of mass, that provides the key to understanding the evolution of our home.
Planetary Orbits: Think about what Newton's laws tell us regarding satellites orbiting around a central body. A satellite can go in ant direction: east to west or west to east, around the equator or over the poles. There are no constraints regarding the orientation of the orbit, and planets could orbit any which way around the Sun. Yet in our solar system we see two very curious features.
All planets orbit in the same direction around the Sun, and this direction is the same as that of the rotation of the Sun.
All planetary orbits are in more or less the same plane. The solar system resembles a bunch of marbles rolling around the same flat dish.
