The latest addition of 65 exoplanets to NASA’s archive of exoplanets contributed to the scientific breakthrough on Monday. This archive is home to discoveries of exoplanets from peer-reviewed scientific papers that have been confirmed using multiple planetary discovery methods.
It’s not just a number,” Jesse Christiansen, lead archival science and research scientist at the NASA Institute for Exoplanet Science at the California Institute of Technology in Pasadena, said in a statement. “Each one of them is a new world, a whole new planet. I’m excited for each one because we don’t know anything about them.”
We are currently living in a golden age of exoplanet discovery. Although the existence of planets outside our solar system has been previously suggested and certainly portrayed in science fiction, these worlds were only first discovered in the 1990s.
The diversity of exoplanets represents groups of planets unlike anything found in our solar system. They include rocky worlds larger than Earth called super-Earths, tiny Neptunes that are larger than Earth but smaller than Neptune, and scorching hot Jupiters that dwarf the largest planet in our solar system and orbit closely around their host stars.
Scientists have also found planets orbiting more than one star and even some around the remains of dead stars called white dwarfs.
To date, of the confirmed exoplanets, 30% are gas giants, 31% are super-Earths, and 35% are Neptune-like. Only 4% of planets are terrestrial or rocky like Earth or Mars.
When Christiansen was a graduate student in the early 2000s, there were only about 100 known exoplanets.
“That’s partly why I wanted to get into this field – because it was so new and exciting that people were finding planets around other stars,” Christiansen said in a question-and-answer session shared by Caltech. “Now, exoplanets are almost normal. My colleague David Ciardi (chief scientist for the NASA Exoplanet Archives) pointed out a few days ago that half of the people alive have never lived in a world where we did not know about exoplanets.
Christiansen said Kepler has helped scientists discover about two-thirds of the 5,000 confirmed planets.
In the new batch of 65 planets, many are deep Earth- and Neptune-like planets, along with some hot Jupiter-sized planets. There are also two Earth-sized planets, Christiansen said, but they are about 620 degrees Fahrenheit (327 degrees Celsius), so they are more like “hot rocks” than habitable planets.
She also noted that one is a system with five planets orbiting a small, cool red dwarf star — not unlike the TRAPPIST-1 system, where a similar star hosts seven rocky planets.
Space observatories join the hunt
The Webb Telescope prepares to study the TRAPPIST system in detail.
The Roman space telescope, Nancy Grace, will be launched in 2027 and will help search for exoplanets using a variety of technologies. The European Space Agency’s ARIEL mission, which will launch in 2029, will study the atmospheres of exoplanets.
Although scientists have confirmed the existence of more than 5,000 exoplanets, there are likely hundreds of billions of them throughout the Milky Way.
“Of the 5,000 known exoplanets, 4,900 are within a few thousand light years of us,” Christiansen said. And think about the fact that we are 30,000 light-years away from the galactic center; If you extrapolate from the tiny bubble around us, that means there are many more planets in our galaxy that we haven’t found yet, up to 100 to 200 billion. It’s amazing.”