More than 5,000 confirmed worlds beyond our solar system: NASA

NASA calls it a “cosmic milestone.”

The space agency has confirmed that there are more than 5,000 exoplanets beyond our solar system and more to be discovered.

After 30 years of space exploration by NASA’s space telescopes, this landmark means we’re one step closer to finding other habitable homes or maybe even reside worlds.

“It’s not just a number,” NASA Exoplanet Science Institute researcher Jessie Christiansen said in a press release. “Each of them is a new world, a whole new planet. I’m excited about each one because we don’t know anything about them.

What are exoplanets?

For most of human history, we have known only a small number of planets orbiting our sun.

An exoplanet is any planet beyond our solar system, according to NASA – and there are probably hundreds of billions of such worlds in our galaxy. Most orbit other stars like our sun, but there are also “rogue planets”, which are free-floating exoplanets.

The first exoplanets were discovered in 1992 by astronomers Alexander Wolszczan and Dale Frail, who found planets outside our solar system orbiting a neutron star.

“If you can find planets around a neutron star, the planets must be pretty much everywhere,” Wolszczan told NASA. “The planet’s production process must be very robust.”

Types of exoplanets

NASA/W. Stenzel

Scientists have classified exoplanets into four types: gas giant, neptunian, super-Earth and terrestrial.

Gas giant planets are usually the size of Jupiter, which is the largest planet in our solar system, or even larger. These planets are usually very hot with temperatures reaching thousands of degrees Celsius.

Neptunian planets are close to the size of Neptune with atmospheres composed mainly of hydrogen and helium and rocky cores.

Super-Earths are larger than Earth, but lighter than Neptune, and are generally terrestrial planets that may not have an atmosphere.

Terrestrial planets are made of rock, silicate, water or carbon. They are either Earth-sized or smaller. According to NASA, a survey of these planets could find signs of habitability.

What worlds have been discovered so far?

The majority of exoplanets have been discovered by NASA’s Kepler space telescope.

Some of the weirdest discoveries include a world that has two suns, just like Luke Skywalker’s home planet, Tatooine in star wars; a planet plunged into total darkness; and a world torn apart by its star.

The Transiting Exoplanet Survey Satellite (TESS) continues to find new exoplanets. NASA expects the next generation of powerful telescopes, starting with the recently launched James Webb Space Telescope, to read whether certain planets have habitable conditions.

Arline J. Mercier