Related topics: orbit · stars · planets · solar system

Smile, wave: Some exoplanets may be able to see us, too

Three decades after Cornell astronomer Carl Sagan suggested that Voyager 1 snap Earth's picture from billions of miles away—resulting in the iconic Pale Blue Dot photograph—two astronomers now offer another unique cosmic ...

Finding vaporized metal in the air of an exoplanet

WASP-121b is an exoplanet located 850 light years from Earth, orbiting its star in less than two days—a process that takes Earth a year to complete. WASP-121b is very close to its star—about 40 times closer than Earth ...

NASA's TESS creates a cosmic vista of the northern sky

NASA's Transiting Exoplanet Survey Satellite (TESS) has discovered 74 exoplanets, or worlds beyond our solar system. Astronomers are sifting through some 1,200 additional exoplanet candidates, where potential new worlds await ...

Carbon-rich exoplanets may be made of diamonds

As missions like NASA's Hubble Space Telescope, TESS and Kepler continue to provide insights into the properties of exoplanets (planets around other stars), scientists are increasingly able to piece together what these planets ...

Natural starshades would help astronomers image exoplanets

In the past few decades, the study of extrasolar planets has grown by leaps and bounds, with the confirmation of over 4000 exoplanets. With so many planets available for study, the focus of exoplanet researchers is shifting ...

Could mini-Neptunes be irradiated ocean planets?

Many exoplanets known today are 'super-Earths,' with a radius 1.3 times that of Earth, and 'mini-Neptunes,' with 2.4 Earth radii. Mini-Neptunes, which are less dense, were long thought to be gas planets, made up of hydrogen ...

Astronomers see unexpected molecule in exoplanet atmosphere

SRON-astronomers have found the signature for aluminum oxide (AlO) in the spectrum of exoplanet WASP-43b. This came as a surprise because AlO is expected to stay hidden in the lower atmospheric layers. It is only the second ...

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Extrasolar planet

An extrasolar planet, or exoplanet, is a planet beyond our Solar System, orbiting a star other than our Sun. As of June 2009[update], 353 exoplanets are listed in the Extrasolar Planets Encyclopaedia. The vast majority have been detected through radial velocity observations and other indirect methods rather than actual imaging. Most announced exoplanets are massive gas giant planets thought to resemble Jupiter, but this is a selection effect (bias) due to limitations in detection technology. Projections based on recent detections of much smaller worlds suggest that lightweight, rocky planets will eventually be found to outnumber extrasolar gas giants.

Extrasolar planets became a subject of scientific investigation in the mid-19th century. Many astronomers supposed that such planets existed, but they had no way of knowing how common they were or how similar they might be to the planets of our Solar System. The first confirmed radial velocity detection was made in 1995, revealing a gas giant planet in a four-day orbit around the nearby G-type star 51 Pegasi. The frequency of detections has tended to increase on an annual basis since then. It is estimated that at least 10% of sun-like stars have planets, and the true proportion may be much higher. The discovery of extrasolar planets sharpens the question of whether some might support extraterrestrial life.

Currently Gliese 581 d, the fourth planet of the red dwarf star Gliese 581 (approximately 20 light years from Earth), appears to be the best example yet discovered of a possible terrestrial exoplanet that orbits within the habitable zone surrounding its star. Although initial measurements suggested that Gliese 581 d resided outside the so-called "Goldilocks Zone", additional measurements place it firmly within.

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