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Extrasolar planet - Wikipedia, the free encyclopedia

An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of 861 such planets (in 677 planetary systems, including 128 multiple planetary systems) have been identified as of March 22, 2013.[5] The Kepler mission has detected over 18,000 additional transit events, including 262 that may be habitable planets.[6][7] In the Milky Way galaxy, it is expected that there are many billions of planets (at least one planet, on average, orbiting around each star, resulting in 100–400 billion exoplanets),[1][2][3][8] with many more free-floating planetary-mass bodies orbiting the galaxy directly.[9] The nearest known exoplanet is Alpha Centauri Bb. Almost all of the planets detected so far are within our home galaxy the Milky Way; however, there have been a small number of possible detections of extragalactic planets. Astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) reported in January 2013, that "at least 17 billion" Earth-sized exoplanets are estimated to reside in the Milky Way Galaxy.[10]

For centuries, many philosophers and scientists supposed that extrasolar planets existed, but there was no way of knowing how common they were or how similar they might be to the planets of the Solar System. Various detection claims, starting in the nineteenth century, were all eventually rejected by astronomers. The first confirmed detection came in 1992, with the discovery of several terrestrial-mass planets orbiting the pulsar PSR B1257+12.[11] The first confirmed detection of an exoplanet orbiting a main-sequence star was made in 1995, when a giant planet was found in a four-day orbit around the nearby star 51 Pegasi. Due to improved observational techniques, the rate of detections has increased rapidly since then.[5] Some exoplanets have been directly imaged by telescopes, but the vast majority have been detected through indirect methods such as radial velocity measurements.[5] Besides exoplanets, "exocomets", comets beyond our solar system, have also been detected and may be common in the Milky Way Galaxy.[10]

Most known exoplanets are giant planets believed to resemble Jupiter or Neptune, but this reflects a sampling bias, as massive planets are more easily observed.[12] Some relatively lightweight exoplanets, only a few times more massive than Earth (now known by the term Super-Earth), are known as well; statistical studies now indicate that they actually outnumber giant planets[13] while recent discoveries have included Earth-sized and smaller planets and a handful that appear to exhibit other Earth-like properties.[14][15][16] There also exist planetary-mass objects that orbit brown dwarfs and other bodies that "float free" in space not bound to any star; however, the term "planet" is not always applied to these objects.

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Rocky alien planets may contain oceans - Indian Express

Rocky alien planets may contain oceans - Indian Express | MHS Astronomy | Scoop.it
Rocky alien planets may contain oceans
Indian Express
All rocky planets develop liquid-water oceans shortly after forming, suggesting that alien worlds potentially teeming with life may be common throughout the Universe, a new study has found.
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????

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Venus vortices go for chaotic multi-storey strolls around the poles

Venus vortices go for chaotic multi-storey strolls around the poles | MHS Astronomy | Scoop.it
A detailed study of Venus' South Polar Vortex shows a much more chaotic and unpredictable cyclone than previously thought.

Via Leopoldo Benacchio
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WOW! Wild Weather

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Migrating planets caused meteor storm - ABC Science Online

Migrating planets caused meteor storm - ABC Science Online | MHS Astronomy | Scoop.it
ABC Science Online
Migrating planets caused meteor storm
ABC Science Online
Meteor storm Migration of giant gas planets such as Jupiter created the biggest meteor storm in our solar system's history, according to a new study.
Cassie Anderson's insight:

Catastrophe that shaped the planets.

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Kelli Hudson's comment, March 26, 2013 8:56 PM
I think that MHS's offering of an astronomy class is astounding! As a science student, I know that reading current information, especially about space, made the course relevant and meaningful. Your Scoop-it demonstrates how "here and now" science is for every student. That is, your Scoop it makes astronomy relevant.I think that MHS's offering of an astronomy class is astounding! As a science student, I know that reading current information, especially about space, made the course relevant and meaningful. Your Scoop-it demonstrates how "here and now" science is for every student. That is, your Scoop it makes astronomy relevant.
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Canadian astronomers detect water in exoplanet's atmosphere - Yahoo! News Canada (blog)

Canadian astronomers detect water in exoplanet's atmosphere - Yahoo! News Canada (blog) | MHS Astronomy | Scoop.it
Yahoo! News Canada (blog)
Canadian astronomers detect water in exoplanet's atmosphere
Yahoo!
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Woot! Water = Life?

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