New astronomical milestone: NASA has just confirmed that the number of known planets beyond our solar system has exceeded 5,000.
NASA Exoplanet Archive
The exoplanet census reached this milestone with a recent batch of 65 exoplanets confirmed thanks to data from NASA’s now-defunct K2 mission, the “second life” of the prolific Kepler space telescope.
Following these latest findings, NASA’s official exoplanet count now stands at 5,005.
“It’s not just a number,” said Jessie Christiansen, a research scientist at NASA’s Exoplanet Science Institute at Caltech in Pasadena, California. “Each exoplanet discovered represents a new world. I get excited about all of them because we don’t know anything about them.”
An exoplanet is any planet that is beyond our solar system, which may or may not be (like Earth) in the habitable zone of its system.
In the 30 years since scientists discovered the first planets orbiting another star, they are now so common that astronomers expect most stars to host at least one planet. So we ‘ve probably just scratched the surface of everything out there . 5,000 exoplanets is a small number compared to what is likely to actually exist. The more we find, the closer we will be to detecting life on another planet.
The Kepler space telescope, launched in 2009, contributed more than 3,000 confirmed exoplanets to the list, with another 3,000 candidates awaiting review.
What are these exoplanets like?
The 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. Most are gaseous, like Jupiter or Neptune, rather than terrestrial, according to NASA’s online database.
Among the recently confirmed exoplanets is K2-377 b , a ‘super Earth’ with a mass of 3.51 Earths that takes 12.8 days to complete one orbit around its star. Some exoplanets orbit two stars at once, like the planet Tatooine from the 1977 “Star Wars” movie.
And how are planets outside the solar system detected?
Studying exoplanets directly is very tricky because they are small, very faint, very distant, and often very close to a bright star whose light drowns out anything the exoplanet might reflect.
There are several techniques. Most are detected by measuring the dimming of the star as an object passes in front of it, called the transit method. Another way to detect exoplanets is the Doppler method, which measures the ‘wobble’ of stars due to the gravitational pull of orbiting planets.
These planets are at the root of the Fermi paradox, which states that we should have detected extraterrestrial life given the fact that there are probably billions of exoplanets in the Milky Way alone. Newer instruments like the James Webb Space Telescope launched in Christmas 2021 are likely to unlock a wealth of new information about alien worlds. At some point, we will find some kind of life somewhere, many scientists think.
“Not only are we going to find lots and lots of exoplanets, but we are also going to start being able to characterize the planets,” the experts say.
Referencia: Jet Propulsion Laboratory. NASA. Cosmic Milestone: NASA Confirms 5,000 Exoplanets. March 21, 2022.
J.L. Christiansen et al. Scaling K2. V. Statistical validation of 60 new exoplanets From K2 campaigns 2–18. arXiv:2203.02087. Submitted March 4, 2022. doi: 10.48550/arXiv.2203.02087.
