Search results
Results from the WOW.Com Content Network
The eight planets of the Solar System with size to scale (up to down, left to right): Saturn, Jupiter, Uranus, Neptune (outer planets), Earth, Venus, Mars, and Mercury (inner planets) A planet is a large, rounded astronomical body that is generally required to be in orbit around a star, stellar remnant, or brown dwarf, and is not one itself. [1]
The definition of the term planet has changed several times since the word was coined by the ancient Greeks. Greek astronomers employed the term ἀστέρες πλανῆται (asteres planetai), 'wandering stars', for star-like objects which apparently moved over the sky.
Eris's discovery contributed to a debate about the definition of a planet because it is 25% more massive than Pluto [219] and about the same diameter. It has one known moon, Dysnomia. Like Pluto, its orbit is highly eccentric, with a perihelion of 38.2 AU (roughly Pluto's distance from the Sun) and an aphelion of 97.6 AU, and steeply inclined ...
A planet in the Solar System beyond the asteroid belt, and hence refers to the gas giants. Pulsar planet: A planet that orbits a pulsar or a rapidly rotating neutron star. Rogue planet: Also known as an interstellar planet. A planetary-mass object that orbits the galaxy directly. Superior planets: Planets whose orbits lie outside the orbit of ...
Because new planets are discovered infrequently, the IAU did not have any mechanism for their definition and naming. After the discovery of Sedna, it set up a 19-member committee in 2005, with the British astronomer Iwan Williams in the chair, to consider the definition of a planet. It proposed three definitions that could be adopted: Cultural
The abundance of water, particularly liquid water, on Earth's surface is a unique feature that distinguishes it from other planets in the Solar System. Solar System planets with considerable atmospheres do partly host atmospheric water vapor, but they lack surface conditions for stable surface water. [209]
The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a young protostar orbited by a protoplanetary disk. There are eight planets within the Solar System; planets outside of the solar system are also known as exoplanets.
The Sun and planets of the Solar System (distances not to scale). The Solar System is the gravitationally bound system of the Sun and the objects that orbit it. It formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.