Thirty years ago, scientists had identified only two planets outside our solar system.
But now, thanks to space telescopes finding new exoplanets by observing “transits” – the slight dimming of light from a star when its tiny planet passes between it and our telescopes – NASA is announcing that more than 5,000 planets have been detected beyond our solar system.
A new batch of 60 planets was recently discovered by the NASA Exoplanet Archive. Those 60 combined with an additional five planets from other observatories now brings the known number of exoplanets to 5,005 to be precise. And NASA’s Exoplanet Exploration page is marking the occasion with a brief animation.
The planets found so far include small, rocky worlds like Earth, gas giants many times larger than Jupiter, and “hot Jupiters” in close orbits around their stars. There are “super-Earths,” which are possible rocky worlds bigger than our own, and “mini-Neptunes,” smaller versions of our system’s Neptune. Add to the mix planets orbiting two stars at once and planets stubbornly orbiting the collapsed remnants of dead stars.
“It’s not just a number,” said Jessie Christiansen, science lead for the archive and a research scientist with the NASA Exoplanet Science Institute at Caltech in Pasadena. “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.”
Since 1992, the number of known exoplanets has doubled roughly every 27 months. And now that rate is on the rise. Scientists believe our galaxy likely holds hundreds of billions of such planets.