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Warm Jupiter exoplanet orbiting distant star detected

Astronomers report the discovery of a new warm Jupiter exoplanet orbiting a distant star in the open cluster Messier 67. The newfound extrasolar world, designated S1429 b, is almost twice as massive as Jupiter. The finding ...

Astronomers discover new Saturn-sized exoplanet

An international team of astronomers reports the discovery of a new exoplanet orbiting a solar-type star. The newfound alien world, designated TOI-1135 b is young, hot and comparable in size to Saturn. The discovery was detailed ...

New ultra-short-period exoplanet discovered

Using NASA's Transiting Exoplanet Survey Satellite (TESS), astronomers have detected a new ultra-short-period exoplanet. The newly found alien world is nearly two times larger than the Earth and orbits its host star in less ...

Astronomers reveal a new link between water and planet formation

Researchers have found water vapor in the disk around a young star exactly where planets may be forming. Water is a key ingredient for life on Earth and is also thought to play a significant role in planet formation, yet ...

Study finds the West is best to spot UFOs

In July of 2023, retired commander in the U.S. Navy David Fravor testified to the House Oversight Committee about a mysterious, Tic Tac-shaped object that he and three others observed over the Pacific Ocean in 2004. The congressional ...

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Planet

A planet (from Greek πλανήτης, from the verb πλανώμαι planōmai I wander), is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.[a]

The term planet is ancient, with ties to history, science, myth, and religion. The planets were originally seen by many early cultures as divine, or as emissaries of the gods. Even today, many people believe in astrology, which holds that the movement of the planets affects people's lives, although such a causation is rejected by the scientific community. As scientific knowledge advanced, human perception of the planets changed, incorporating a number of disparate objects. Even now there is no uncontested definition of what a planet is. In 2006, the IAU officially adopted a resolution defining planets within the Solar System. This definition has been both praised and criticized, and remains disputed by some scientists.

The planets were thought by Ptolemy to orbit the Earth in deferent and epicycle motions. Though the idea that the planets orbited the Sun had been suggested many times, it was not until the 17th century that this view was supported by evidence from the first telescopic astronomical observations, performed by Galileo Galilei. By careful analysis of the observation data, Johannes Kepler found the planets' orbits to be not circular, but elliptical. As observational tools improved, astronomers saw that, like Earth, the planets rotated around tilted axes, and some share such features as ice-caps and seasons. Since the dawn of the Space Age, close observation by probes has found that Earth and the other planets share characteristics such as volcanism, hurricanes, tectonics, and even hydrology. Since 1992, through the discovery of hundreds of extrasolar planets (planets around other stars), scientists are beginning to understand that planets throughout the Milky Way Galaxy share characteristics in common with our own.

Planets are generally divided into two main types: large, low-density gas giants, and smaller, rocky terrestrials. Under IAU definitions, there are eight planets in the Solar System. In order from the Sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four gas giants, Jupiter, Saturn, Uranus, and Neptune. The Solar System also contains at least five dwarf planets: Ceres, Pluto (originally classified as the Solar System's ninth planet), Makemake, Haumea and Eris. With the exception of Mercury, Venus, Ceres and Makemake, all of these are orbited by one or more natural satellites.

As of June 2009, there are 353 known extrasolar planets, ranging from the size of gas giants to that of terrestrial planets.

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