What Is The Closest Exoplanet?

Our solar system consists of planets orbiting the sun. Exoplanets are planets that exist outside our solar system, but also orbit a star. There’s over four thousand confirmed exoplanets, with the nearest one to Earth being Proxima Centauri b.

Learning about exoplanets is incredibly difficult. They’re tricky to detect, and are most commonly confirmed based on the effect these planets have on their star. Any further details are even trickier to come by, with observation helping us to develop theories.

Exoplanets are fascinating, especially as they might reveal the potential for life on other planets. Read this guide to find out more about our exoplanet neighbors.

What Is An Exoplanet?

An exoplanet is a complicated sounding name for something that’s actually quite simple. An exoplanet is any planet orbiting a star outside the solar system. 

In our solar system, all the planets are in orbit around the sun. An exoplanet is similar, but it’s a planet orbiting a sun outside our solar system.

Exoplanets can be incredibly difficult to detect, because the bright light of the star they orbit makes them difficult to see. For that reason, to find exoplanets we have to look for evidence that indicates a planet is in orbit. This has been typically accomplished by looking for “wobbly” stars. As the planet orbits off-center, from a distance it can seem as though the star is “wobbly”. Scientists can use this method to find larger exoplanets.

Another way to detect exoplanets, and to find smaller exoplanets, is the “transit” method. As the exoplanet passes in front of the star, the light from the star is partly blocked. By detecting this reduced brightness, scientists can find smaller exoplanets, and even figure out the size.

By using these methods, we’ve been able to confirm the identity of over 4000 exoplanets, with thousands more that have potentially been detected.

What Is The Closest Exoplanet To Earth?

Proxima Centauri b is the closest exoplanet to Earth. It orbits Proxima Centauri, a red dwarf star that’s the closest star to our sun. Proxima Centauri b is roughly 4.2 light years away from earth, and it inhabits the habitable zone of its star.

Proxima Centauri b isn’t the only planet that orbits Proxima Centauri. Proxima Centauri c is thought to be a gas dwarf planet, and it orbits much further out, on a colder orbital track.

It is thought that there could potentially be a third exoplanet orbiting Proxima Centauri, smaller than the others, and closer to the star. However, this has yet to be confirmed.

Proxima Centauri c was only discovered in 2016. Before this, the closest known exoplanet to Earth was considered to be Epsilon Eridani b. Orbiting the star Epsilon Eridani, observations indicate that the exoplanet has a mass roughly 1.5 times that of Jupiter. 

Due to the proximity of the Proxima Centauri star, it’s thought that there are unlikely to be any exoplanets closer to Earth than Proxima Centauri b. Any stars closer would have been discovered at this point. As there are no closer stars, there are no closer exoplanets.

There is a small possibility that a rogue planet may exist closer to Earth than Proxima Centauri b. Rogue planets are interstellar objects with masses comparable to the planets of our solar system. Rather than orbiting a star, rogue planets travel freely. Although rogue planets have been confirmed, it’s thought that it’s unlikely one would be that close to Earth.

Although there is always more to learn about our galaxy, it seems no new discoveries will take the title of “closest exoplanet” away from Proxima Centauri b. 

All About Proxima Centauri B

Proxima Centauri b is the nearest exoplanet to Earth, and it could potentially be habitable. Although we still don’t know much about our nearest neighbor, observation will teach us more about this fascinating exoplanet.

Proxima Centauri b was first discovered in 2016, using Doppler spectroscopy. This is an indirect method used to identify exoplanets by detecting Doppler shifts in the spectrum of the star the planet orbits. This is often known as the “wobble method”.

Proxima Centauri b is thought to be similar in mass to Earth, with a minimum mass of 1.17 Earth mass. However, these are only estimates, and the size and radius are still unknown.

Day and night are thought to be very different on Proxima Centauri b. In fact, one half of the planet might have no daytime at all. Because Proxima Centauri is a dwarf star, it has less heat. A planet needs to be closer to be warm, and this proximity can “tidal lock” the planet into place. One side will always face the star, while the other will always face away.

A year on Proxima Centauri b will pass in just 11 days. The close proximity to the star allows the exoplanet to orbit in a very short period of time. The star would be much larger in the sky on Proxima Centauri b.

Other than that, there’s very little we know about Proxima Centauri b, including how it was formed. It’s thought that the exoplanet may have formed at a greater distance, and later migrated into a closer orbit. How it formed, and the composition of elements used to form the exoplanet, could make a massive difference to how we understand Proxima Centauri b.

How Long Would It Take To Get To Proxima Centauri B?

Proxima Centauri b may be the closest exoplanet to Earth, but it’s still a distance of 4.2 light years away. In terms of the universe, and even the galaxy, this is a short distance. But even with our greatest available technology, it would still take around 6,300 years to reach Proxima Centauri b. 

What Is The Second Closest Exoplanet To Earth?

Ross 128 b is an exoplanet orbiting in the habitable zone around the red dwarf star Ross 128. At a distance of 11 light years away, it’s thought to be the second-closest terrestrial planet to Earth. It may even be inside the habitable zone of Ross 128, meaning there could be water.

Ross 128 b has many similarities to both Earth and Proxima Centauri b. It’s thought to be roughly 1.3 times the mass of Earth, and experience similar temperatures.

Like Proxima Centauri b, Ross 128 b orbits very close to its star. It may also be tidal locked, with one side always experiencing day time. A year on Ross 128 b would last for around 10 days.

What Is The Closest Habitable Exoplanet To Earth?

Proxima Centauri b is both the closest exoplanet to Earth, and the closest potentially habitable exoplanet. For a planet to be considered hospitable, there has to be the possibility that liquid water might exist on the surface.

Potentially, Proxima Centauri could have the right conditions for liquid water to be found on the surface, and an atmosphere. However, there’s still so much that we don’t know about Proxima Centauri b, and about the habitability of red dwarf systems. Still, it’s an exciting area for future research.


Exoplanets are planets that orbit a star outside our solar system. The nearest one to us is Proxima Centauri b, and the size and warmth of the planet make it potentially habitable. However, at 4.7 light years away, with current technology, it would take over six thousand years to visit.

Gordon Watts