NASA has confirmed that there are more than 5,000 known planets outside our solar system, known as exoplanets.
The US space agency has added another 65 exoplanets to the online NASA Exoplanet Archive, bringing the grand total to 5,005.
Exoplanets found so far include small, rocky worlds like Earth, gas giants many times larger than Jupiter, and ‘hot Jupiters’ in scorchingly close orbits around their stars.
However, NASA stresses that 5,005 is only ‘a tiny fraction’ of all the planets in the Milky Way galaxy alone, which could number hundreds of billions.
NASA confirms there are more than 5,000 planets beyond our solar system including several ‘hot Jupiters’, ‘super-Earths’ and ‘mini-Neptunes’. An artist’s impression of the variety of different exoplanets are depicted here
‘It’s not just a number,’ said Jessie Christiansen, research scientist with the NASA Exoplanet Science Institute at Caltech in Pasadena, California.
‘Each one of them is a new world, a brand-new planet. I get excited about every one because we don’t know anything about them.’
The majority of exoplanets are gaseous, like Jupiter or Neptune, rather than terrestrial, according to NASA’s online database.
The archive records exoplanet discoveries that appear in peer-reviewed, scientific papers that have been confirmed using multiple detection methods or by analytical techniques.
Among the most recently confirmed exoplanets are K2-377 b, a ‘super Earth’ with a mass of 3.51 Earths that takes 12.8 days to complete one orbit of its star.
Another, called TOI-1064 b, is a ‘potentially rocky world larger than Earth, according to NASA.
Most exoplanets are found by measuring the dimming of a star that happens to have a planet pass in front of it, called the transit method.
Another way to detect exoplanets, called the Doppler method, measures the ‘wobbling’ of stars due to the gravitational pull of orbiting planets.
The more than 5,000 exoplanets confirmed in our galaxy so far include a variety of types – among them a mysterious variety known as ‘super-Earths’ because they are larger than our world and possibly rocky
NASA’s milestone comes 30 years after the first exoplanets were discovered, back in 1992.
In January that year, Aleksander Wolszczan and Dale Frail announced the discovery of two rocky planets orbiting PSR B1 257+12, a pulsar in the constellation Virgo. A further planet was discovered in the system in 1994.
Finding just three planets around this spinning star essentially opened the floodgates for exoplanets, said Wolszczan, who still searches for exoplanets as a professor at Penn State.
‘If you can find planets around a neutron star, planets have to be basically everywhere,’ he told NASA. ‘The planet production process has to be very robust.’
Some of the exoplanets…
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