Described as a cosmic milestone, NASA confirmed the existence of more than 5000 exoplanets after analysing the latest batch from the planetary odometer listing 65 new exoplanets.
1. 5000-plus worlds
Using NASA’s Transiting Exoplanet Survey Satellite (TESS), the 5000-plus worlds 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. Among them is a new system of five small planets orbiting a red dwarf star called K2-384, in a similar fashion to the famous TRAPPIST-1 system.
The TRAPPIST-1 planets have been examined with ground and space telescopes. Related studies revealed not only their diameters, but the subtle gravitational influence these seven closely packed planets have upon each other; from this, scientists determined each planet’s mass.
Most of the other newcomers are Super-Earths, which are possible rocky worlds, bigger than our own, and mini-Neptunes, as well as a few Jupiter-sized worlds.
It’s 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.
Jessie Christiansen, science lead for the NASA Exoplanet Archive and research scientist with the NASA Exoplanet Science Institute at Caltech in Pasadena
2. Exoplanets
An exoplanet is any planet beyond our solar system. Most orbit other stars, but free-floating exoplanets, called rogue planets, orbit the galactic center and are untethered to any star.
The first planet detected around a Sun-like star, in 1995, turned out to be a hot Jupiter: a gas giant about half the mass of our own Jupiter in an extremely close, four-day orbit around its star. A year on this planet lasts only four days.
“We’re opening an era of discovery that will go beyond simply adding new planets to the list,“ said Alexander Wolszczan, the lead author on the paper that, 30 years ago, unveiled the first planets to be confirmed outside our solar system.
Based on data retrieved by NASA’s Kepler Space Telescope, we know that there are more planets than stars in the galaxy.
3. The best is yet to come
The number of exoplanets could rise to tens of thousands within a decade, as more powerful satellites and robotic telescopes are being lofted into space.
NASA’s TESS, launched in 2018, continues to make new exoplanet discoveries. Soon, powerful next-generation telescopes and their highly sensitive instruments, like the recently launched James Webb Space Telescope, will capture light from the atmospheres of exoplanets, reading which gases are present to potentially identify tell-tale signs of habitable conditions.
Now we live in a universe of exoplanets. The count of confirmed planets is in the thousands and rising. That’s from only a small sampling of the galaxy as a whole.
NASA
The James Webb telescope is poised to study the TRAPPIST system in detail. The Nancy Grace Roman Space Telescope will launch in 2027 and aid in the search for exoplanets with a variety of techniques. The European Space Agency’s ARIEL mission, launching in 2029, will also study exoplanet atmospheres.
Of the 5,000 exoplanets known, 4,900 are located within a few thousand light-years of us. And think about the fact that we’re 30,000 light-years from the center of the galaxy; if you extrapolate from the little bubble around us, that means there are many more planets in our galaxy we haven’t found yet.
Jessie Christiansen, science lead for the NASA Exoplanet Archive and research scientist with the NASA Exoplanet Science Institute at Caltech in Pasadena
Describing the milestone as “mind-blowing”, Jessie Christiansen predicts that there must be as many as 100 to 200 billion exoplanets still to be found in our galaxy, the Milky Way.
The research has been accepted for publication in the Astronomical Journal.
