'Super-Earths and mini-Neptunes': A look at the 5000 other worlds that lie beyond ours in space
Sunday, 27 March 2022
There are now more than 5000 confirmed planets beyond our solar system, according to Nasa.
In a statement, the space agency said that not so long ago, we lived in a universe with only a small number of known planets orbiting the Sun. But after 30 years of space exploration and a new raft of recent discoveries, more than 5000 planets have now been confirmed to exist beyond our own solar system.
The space agency reached the milestone number after adding another 65 exoplanets to its archive this week. Exoplanets are planets that are outside Earth’s immediate solar family, and they orbit around other stars.
The archive records exoplanet discoveries that appear in peer-reviewed, scientific papers, and that have been confirmed using multiple detection methods or by analytical techniques, Nasa explained.
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Nasa research scientist Jessie Christiansen said the milestone was “not just a number”.
“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.”
Among the 5000 planets found to date are huge gas giants much larger than Jupiter. Nicknamed “hot Jupiters,” these gas giants orbit so closely to their stars that their temperatures soar into the thousands of degrees.
Other types of exoplanets include “super-Earths,” which are possible rocky worlds bigger than our own, “mini-Neptunes,” which are smaller versions of our system’s Neptune, and terrestrial planets which are rocky, Earth-sized or smaller.
Of the confirmed exoplanets to date, 35 per cent are Neptune-like, 31 per cent are super-Earths, 30 per cent are gas giants, and just 4 per cent are terrestrial, or rocky planets like Earth or Mars.
The search for exoplanets has come a long way in the past three decades, with scientist Alexander Wolszczan saying in a statement that we're in an era of discovery that goes beyond simply adding new planets to the list.
There are telescopes in space, on the ground and even in the air that are being used to hunt exoplanets, and Nasa has telescopes in space currently studying exoplanets.
“There’s tons of exoplanets out there,” astronomer Aurora Kesseli told Science News, “and even more waiting to be discovered.”
The ultimate goal of the exoplanet exploration programme is to discover planets around other stars, characterise their properties, and identify planets that could harbour life.
The recently launched James Webb Space Telescope is able to capture light from the atmospheres of exoplanets and read which gases are present to potentially identify tell-tale signs of habitable conditions.
“To my thinking, it is inevitable that we’ll find some kind of life somewhere – most likely of some primitive kind,” Wolszczan said.
The close connection between the chemistry of life on Earth and chemistry found throughout the universe, as well as the detection of widespread organic molecules, suggests detection of life itself is only a matter of time, he said.