 To measure distances within the solar system, scientists have developed a measuring unit based on the average Earth-Sun distance. This distance is called the astronomical unit and is equal to 149,600,000 kilometers or, using scientific notation, 1.496 x 108 kilometers. When solar system distances are expressed in astronomical units, it is easy to get a relative scale of distances (i.e., 0.7 times as far from the Sun as Earth, 5.2 times as far from the Sun as Earth, etc.). |
| It is not feasible to "power one's way" to another planet in our solar system. Instead, a vessel or shuttle traveling to another planet must travel fast enough to achieve a speed that will put the shuttle into an elliptical orbit about the Sun. Once in orbit, the shuttle becomes like one of the Sun's orbiting bodies and obeys the laws of planetary motion. To reach the desired planet, the shuttle's ellipse must tangentially intersect or just touch the orbit of the desired planet. To get home, it must also intersect the Earth's orbit. |
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