How Many Exoplanets Are There? Scientists Discover Dozens of New Worlds

NASA said 40 new exoplanets have been discovered, bringing the known total to 4,512.

The space agency's Exoplanet Exploration Program announced the new planets in a tweet on Monday. The vast majority of them were discovered using data from the Kepler space telescope, which retired in 2018.

NASA Exoplanets tweeted that "astronomers are still finding worlds" in Kepler's old measurements.

At the time of writing, NASA listed 7,721 planetary candidates that could potentially be exoplanets, but the agency is still awaiting confirmation before it adds them to the total.

The database, outlining all of the confirmed exoplanets, is available online and is updated continuously.

Among the most recent additions to the database are TOI-251 b, a planet with the mass of Jupiter that is located 325 light-years away. It takes just 4.9 days to complete one orbit of its star.

Another is TOI-178 b, an exoplanet that falls under the "super Earth" category, with a mass of around 1.5 times that of our own planet. It takes less than two days to orbit its star.

An exoplanet is defined as any planet that exists beyond our own solar system. Using various detection methods, researchers can determine how large these planets are, what their mass is, and even what they are made of.

Exoplanet discovery is a relatively recent branch of astronomy. The first ones were discovered in the 1990s, and since then the number has shot up dramatically.

Scientists have to rely on telescope observations because exoplanets are way too far away for us to visit with existing technology. Even the closest known exoplanet, Proxima Centauri b, is four light years away.

A Very Long Space Journey

If someone were to get into their car and drive toward the planet at 60 miles per hour, it would take them 47 million years to get there. Even the Voyager probes, which are flying out of our solar system at tens of thousands of miles per hour, would take around 75,000 years to get there, according to NASA.

Scientists detect exoplanets using a variety of methods. Many are found using the transit method, in which scientists look at a distant star and measure how much it dims when an exoplanet passes in front of it.

Of particular interest are exoplanets that exist within the habitable zone of their stars—an area not too hot and not too cold for liquid water to exist on their surface. Such planets could be potentially habitable and play a key part in the ongoing search for life elsewhere in the universe.

Some exoplanets, such as K2-18b, which is located around 124 light-years away, have been identified as more likely to be habitable than others.

A stock image shows an artist's impression of moons orbiting an exoplanet. Thousands of exoplanets have been confirmed using detection methods over the years. Pitris/Getty