Most comets are thought to originate in the outermost parts of the solar system, the Kuiper belt and the much more distant Oort cloud. Many comets have orbits that take them thousands of times farther out than Neptune. Neptune, the outermost planet, orbits the Sun from about 30 AU, or 2.8 billion miles (4.5 billion kilometers), away. There are eight planets in the solar system. One astronomical unit (AU) is defined as the average distance between Earth and the Sun. Astronomers use this distance as a basic unit of length in describing the vast distances of the solar system. Earth orbits the Sun at an average distance of about 93 million miles (150 million kilometers). ( See also the solar system at a glance.) The Solar System in SpaceĪstronomers do not know exactly how far out the solar system extends.
This dust and gas is very thinly scattered in the huge expanses between the planets and other bodies in the solar system. The solar system’s smallest members are the microscopic particles of dust and the even smaller atoms and molecules of gas of the interplanetary medium. It is quite small, however, compared to the Sun or the planet Jupiter, which are the largest members of the solar system.
Interactive Encyclopædia Britannica, Inc.Įarth is one of the larger bodies of the solar system. Proxima Centauri (closest star to Earth other than the Sun)Ĭenter of the Milky Way Galaxy (the galaxy to which Earth belongs)Īndromeda Galaxy (closest external galaxy) Travel time estimates to Pluto at its maximum distance from Earth are provided in parentheses, since Pluto's distance from **Pluto's orbit crosses Neptune's so that Pluto's minimum possible distance from Earth is actually a bit less than Neptune's. Also, in reality,Ī jet could not escape from Earth's gravity, and spacecraft have more complex trajectories. Is of course not the case) and that each body remains at about its minimum possible distance from Earth. For ease of calculation, they assume that the celestial bodies are not in motion (which Ray of light, 186,282 miles (299,792 kilometers) per second Rocket, 25,000 miles (40,250 kilometers) per hour Travel time from Earth to various objects in the solar system and beyond* destination Presumed similar to that of comets: water ice, other ices, silicates, organics Perhaps similar to Pluto: water ice, silicates, organics Presumed similar to that of comets: water ice, other ices, silicates ***Earth's mass is about 6.58 × 10 21 tons (5.98 × 10 24 kilograms).ĥ–30 (mainly between orbits of Jupiter and Neptune)
**By comparison, the density of water is 1 gram/centimeter 3. Sun, about 93 million miles (150 million kilometers). One astronomical unit (AU) is the average distance between Earth and the *Average distance, except where ranges are given. Properties of major objects of the solar system object
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