"Accordingly, since nothing prevents the earth from moving...
...I suggest that we should now consider also whether several motions suit it, so that it can be regarded as one of the planets. For, it is not the center of all the revolutions." - Nicolaus Copernicus
The Size and Shape of Orbits
Figure below shows the relative sizes of the orbits of the planets, asteroid belt, and Kuiper belt. In general, the farther away from the Sun, the greater the distance from one planet’s orbit to the next. The orbits of the planets are not circular but slightly elliptical, with the Sun located at one of the foci (see opening image).
The relative sizes of the orbits of planets in the solar system. The inner solar system and asteroid belt is on the upper left. The upper right shows the outer planets and the Kuiper belt.
While studying the solar system, Johannes Kepler discovered the relationship between the time it takes a planet to make one complete orbit around the Sun, its "orbital period," and the distance from the Sun to the planet. If the orbital period of a planet is known, then it is possible to determine the planet’s distance from the Sun. This is how astronomers without modern telescopes could determine the distances to other planets within the solar system.
Scaling the solar system creates a scale to measure all objects in solar system: http://www.youtube.com/watch?v=-6szEDHMxP4 (4:44).
- The eight planets orbit the Sun along slightly elliptical paths, with Sun located at one of the foci.
- Kepler discovered that by using a planet's orbital period, it is possible to determine its distance from the Sun.
- The farther the planets are from the Sun, the greater their distance from each other.
Use this resource to answer the questions that follow.
1. What does this animation show?
2. Describe what you see in this animation.
3. How long would it take to travel the solar system on today's fastest spacecraft?
4. How long would the trip take at the speed of light?
5. How fast is this animation?
1. When you look at the diagram of planet orbits, which planet doesn't fit the criteria of a planet?
2. How can a planet's orbital period be used to determine a its distance from the Sun?
3. Why would your age be different on a different planet?