Related topics: stars · planets · solar system · jupiter

Distant giant planets form differently than 'failed stars'

A team of astronomers led by Brendan Bowler of The University of Texas at Austin has probed the formation process of giant exoplanets and brown dwarfs, a class of objects that are more massive than giant planets, but not ...

Why some planets eat their own skies

For many years, for all we knew, our solar system was alone in the universe. Then better telescopes began to reveal a treasure trove of planets circling distant stars.

Water common—yet scarce—in exoplanets

The most extensive survey of atmospheric chemical compositions of exoplanets to date has revealed trends that challenge current theories of planet formation and has implications for the search for water in the solar system ...

First giant planet around white dwarf found

Researchers using ESO's Very Large Telescope have, for the first time, found evidence of a giant planet associated with a white dwarf star. The planet orbits the hot white dwarf, the remnant of a Sun-like star, at close range, ...

Gas giant composition not determined by host star

A surprising analysis of the composition of gas giant exoplanets and their host stars shows that there isn't a strong correlation between their compositions when it comes to elements heavier than hydrogen and helium, according ...

New 'warm Jupiter' exoplanet discovered

An international team of astronomers reports the discovery of a new "warm Jupiter" alien world transiting a main sequence late F-type star on an eccentric orbit. The newfound exoplanet, designated TOI-677 b, is about 20 percent ...

Why a rocky planet with three suns has astronomers' attention

Planets that are even a little like Earth are hard to find. That's why when astronomers like Jennifer G. Winters come across a body that may be solid, rocky, and possibly have its own atmosphere, they get excited. And especially ...

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Gas giant

A gas giant (sometimes also known as a Jovian planet after the planet Jupiter, or giant planet) is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in our Solar System: Jupiter, Saturn, Uranus, and Neptune. Many extrasolar gas giants have been identified orbiting other stars.

Gas giants can be subdivided into different types. The "traditional" gas giants, Jupiter and Saturn, are composed primarily of hydrogen and helium. Uranus and Neptune are sometimes considered a separate subclass called ice giants, as they are mostly composed of water, ammonia, and methane; the hydrogen and helium in Uranus and Neptune is mostly in the outermost region. Among extrasolar planets, Hot Jupiters are gas giants that orbit very close to their stars and thus have a very high surface temperature; perhaps due to the relative ease of detecting them, Hot Jupiters are currently the most common form of extrasolar planet known.

Gas giants are commonly described as lacking a solid surface, although a more accurate description is to say that they lack a clearly-defined surface. Although they have rocky or metallic cores - in fact, such a core is thought to be required for a gas giant to form - the majority of the mass of Jupiter and Saturn is hydrogen and helium. In the planet's upper layers, these elements are gaseous, as they are on Earth, but further down in the planet's interior, they become compressed into liquids or solids, which become denser toward the core. Similarly, although the majority of Uranus and Neptune is icy, the extreme heat and pressure of these planets' interiors put the ices into less familiar physical states. Therefore, one cannot "land on" gas giants in a traditional sense. Terms such as diameter, surface area, volume, surface temperature, and surface density may refer only to the outermost layer visible from space.

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