NASA confirms there are 5,000 planets outside our solar system

NASA has confirmed that there are over 5,000 known planets outside our solar system, called exoplanets.

The US space agency has added another 65 exoplanets to NASA’s Exoplanet Online Archive, bringing the total to 5,005.

Exoplanets discovered so far include small, rocky Earth-like worlds, gas giants several times larger than Jupiter, and “hot Jupiters” in extremely close orbits around their stars.

However, NASA points out that 5,005 is just a “tiny fraction” of all the planets in the Milky Way galaxy alone, which could number in the hundreds of billions.

NASA confirms that there are more than 5,000 planets beyond our solar system, including several “hot Jupiters”, “super-Earths” and “mini-Neptunes”. An artist’s impression of the variety of different exoplanets is shown here

HOW MANY EXOPLANETS ARE THERE?

An exoplanet is a planet located beyond our solar system. Most orbit other stars, but free-floating exoplanets, called rogue planets, orbit the galactic center and are not tied to any star.

5,005 exoplanets have been confirmed since the first exoplanet discoveries in the early 1990s, as of March 22, 2022.

The majority of these exoplanets are gaseous, like Jupiter or Neptune, rather than terrestrial, according to NASA’s online database.

The nearest exoplanet is called Proxima Centauri b, about 4.2 light years from our Sun.

“It’s not just a number,” said Jessie Christiansen, a NASA Exoplanet Science Institute researcher at Caltech in Pasadena, California.

“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.

The majority of exoplanets are gaseous, like Jupiter or Neptune, rather than terrestrial, according to NASA’s online database.

The archive records discoveries of exoplanets that appear in peer-reviewed scientific papers and that have been confirmed using multiple detection methods or by analytical techniques.

Among the most recently confirmed exoplanets are K2-377 b, a “super Earth” with a mass of 3.51 Earths that takes 12.8 days to orbit its star.

Another, called TOI-1064 b, is a “potentially rocky world larger than Earth”, according to NASA.

Most exoplanets are found by measuring the dimming of a star in front of which a planet passes, called the transit method.

Another way to detect exoplanets, called the Doppler method, measures the “wobble” of stars due to the gravitational pull of orbiting planets.

The more than 5,000 exoplanets confirmed in our galaxy so far include a variety of types - among them a mysterious variety known as

The more than 5,000 exoplanets confirmed in our galaxy so far include a variety of types – including a mysterious variety known as “super-Earths” because they are larger than our world and possibly rocky

NASA’s milestone comes 30 years after the discovery of the first exoplanets in 1992.

THREE ‘EXOPLANETS’ ARE REALLY STARS

Scientists examined the thousands of confirmed exoplanet discoveries in the Milky Way galaxy, and three of them turned out to be stars.

A team from MIT in Cambridge examined the discovered planets using NASA’s Kepler space telescope, double-checking the measurements to see which match known planet sizes.

They have identified three objects that are simply too big to be planets, based on new, more precise measurements taken by the European Space Agency’s Gaia Telescope.

Read more: Three “exoplanets” are actually stars

In January of the same year, Aleksander Wolszczan and Dale Frail announced the discovery of two rocky planets orbiting PSR B1 257+12, a pulsar in the constellation Virgo. Another planet was discovered in the system in 1994.

Finding just three planets around this spinning star essentially opened the floodgates for exoplanets, said Wolszczan, who still researches exoplanets as a professor at Penn State.

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

Some of the exoplanets since discovered, like Kepler 16-b, orbit two stars at once, like the planet Tatooine in “Star Wars.”

About 200 light-years away, Kepler-16b weighs about one-third the size of Jupiter and has a radius three-quarters that of Jupiter, making it similar to Saturn in size and mass.

Another exoplanet called WASP-121b, about 850 light-years from Earth, is an example of a “hot Jupiter” – a gas giant Jupiter-like planet in a close orbit around its parent star.

WASP-121b has one of the shortest orbits detected to date, circling its star in just 30 hours.

It is tidal locked, which means the same side always faces its star, while it is colder the “night” side is forever turned towards space.

Gliese 486b, meanwhile, is an example of a “super Earth” – a planet larger than Earth but smaller than the four gas giants Jupiter, Saturn, Neptune and Uranus.

Some exoplanets orbit two stars at once, like the planet Tatooine in the movie

Some exoplanets orbit two stars at once, like the planet Tatooine in the 1977 film ‘Star Wars’ (pictured)

Artist's impression of the exoplanet Kepler-16b, the most

Artist’s impression of exoplanet Kepler-16b, the most “Tatooine-like” planet ever found in our galaxy. Kepler-16b is represented by a small black circle surrounding two stars. The larger of the two stars, a K dwarf, is about 69% the mass of our sun, and the smaller, a red dwarf, is about 20% the mass of the sun.

Gliese 486b is the only planet detected so far orbiting the small star and has a radius 1.3 times larger than Earth but is 2.8 times more massive.

The planet has an iron silicate composition similar to Earth’s composition but is much hotter, with a surface temperature of 802°F (428°C), according to a 2021 study.

GJ 367 b, meanwhile, is exposed to an enormous amount of radiation, due to its short distance from its star – around 620,000 miles – which it orbits in just eight hours.

With a diameter of 5,560 miles, GJ 367 b is slightly larger than Mars (4,200 miles) but has the composition of Mercury.

NASA said its James Webb Space Telescope (pictured here in space) will capture light from exoplanet atmospheres to read what gases are present to potentially identify telltale signs of habitable conditions

NASA said its James Webb Space Telescope (pictured here in space) will capture light from exoplanet atmospheres to read what gases are present to potentially identify telltale signs of habitable conditions

Scientists are still trying to learn more about the exact composition of exoplanets and their atmospheres.

NASA said its James Webb Space Telescope will capture light from exoplanet atmospheres to read what gases are present to potentially identify telltale signs of habitable conditions.

The $10bn (£7.4bn) observatory, which launched on Christmas Day, will explore the universe in the infrared spectrum, allowing it to peer through clouds of gas and dust where stars are born.

EXOPLANETS HAVE “EXOTIC” ROCKS THAT CANNOT BE FOUND IN OUR SOLAR SYSTEM

Rocky planets outside our solar system, called exoplanets, are made up of “exotic” rock types that don’t even exist in our planetary system, according to a 2021 study.

Researchers have used data from the telescope to analyze white dwarfs – ancient stars that once gave life just like our Sun – in a bid to uncover the secrets of their ancient surrounding planets.

About 98% of all stars in the universe will eventually become white dwarfs, including our own Sun.

Experts have found that some exoplanets have rock types that don’t exist, or simply can’t be found, on planets in our solar system.

These types of rocks are so “strange” that the authors had to create new names for them, including “quartz pyroxenites” and “periclase dunites”.

Some 4,374 exoplanets have been confirmed in 3,234 systems since the first exoplanet discoveries in the early 1990s.

The majority of these exoplanets are gaseous, like Jupiter or Neptune, rather than terrestrial, according to NASA’s online database.

Read more: Rocky exoplanets are even weirder than we thought, study finds

Arline J. Mercier