Proxima Centauri

Proxima Centauri is the closest star to Earth after the Sun. It is 4.25 light-years away in the southern constellation of Centaurus. This small, faint star was found in 1915 and is part of the Alpha Centauri star system.

Proxima Centauri is a red dwarf. It has a mass that is about 12.5% of the Sun's mass. Though it is very dim and hard to see without a telescope, it sometimes gets brighter quickly because of magnetic activity. Because it burns its fuel slowly, Proxima Centauri will keep shining for about four trillion years.

Scientists have found two planets around Proxima Centauri. The closest one, called Proxima Centauri b, is in the star’s habitable zone. This means it might have liquid water. However, the star’s bright flares make this uncertain. Another smaller planet, Proxima Centauri d, orbits very close to the star. There might also be a third, farther planet called Proxima Centauri c.

General characteristics

Proxima Centauri is a small, dim star known as a red dwarf. It is very faint and cannot be seen without special tools. It shines with only a tiny bit of the Sun’s brightness, mostly in infrared light.

This star is very dense, fitting a lot of mass into a small space. It is about one-seventh the width of the Sun but has a very high density. Its mass is about 12% of the Sun’s mass, which is around 129 times the mass of Jupiter.

Structure and fusion

Proxima Centauri is a small star. Its whole interior moves, which helps it share energy. This movement creates a magnetic field. Sometimes, this field causes bright flashes called flares. These flares get very hot and bright, but they only last a short time.

Even when Proxima Centauri is quiet, it is still very active, more than the Sun. This activity makes the star's outer layer very hot. Over time, stars like this tend to calm down. Proxima Centauri is already showing signs of this as it ages.

Life phases

Proxima Centauri is a small red dwarf star. It will stay on its main sequence for about four trillion years. During this time, it will slowly become smaller and hotter. It will eventually turn into what is called a "blue dwarf."

Near the end of this long period, it will become brighter. It will reach about 2.5% of the Sun's brightness. This might warm any planets that orbit it for several billion years.

Eventually, Proxima Centauri will use up its hydrogen fuel. It will transform into a helium white dwarf without becoming a red giant first. It will then slowly cool down over time.

Scientists think the Alpha Centauri system may have formed when a low-mass star like Proxima was captured by a more massive pair of stars. This could mean that Proxima and the other stars share similar elements. Its gravity might have also affected the early disks around the other stars. This could have brought more water and other materials to any planets forming there.

Motion and location

Proxima Centauri is the closest star to the Sun. It is about 4.25 light-years away. Proxima Centauri moves quickly across the sky. It is part of the Alpha Centauri system, which has two other stars. From Earth, Proxima Centauri looks very faint because it is a small, cool star.

Proxima Centauri is often called Alpha Centauri C. This is because it is connected to the Alpha Centauri binary star system. It orbits this system in a long path, sometimes coming close to the two main stars and then moving far away again. Together with several other stars, Proxima Centauri moves through space as part of a group.

Main article: Alpha Centauri

Planetary system

As of 2025, three planets have been found around Proxima Centauri. One of these planets, called Proxima Centauri b, is about the size of Earth. It is in the habitable zone, where liquid water could exist. Another planet, Proxima Centauri c, orbits farther out and might be a gas dwarf. A third planet, Proxima Centauri d, is one of the smallest planets ever found.

Scientists have looked for planets around Proxima Centauri since the 1970s. In 2016, they confirmed Proxima Centauri b using special telescopes. They also found hints of other planets, but some discoveries are still being checked.

Observational history

In 1915, an astronomer named Robert Innes found a star that moved like Alpha Centauri. He called it Proxima Centauri. Later, it was found to be about the same distance from the Sun as Alpha Centauri. At that time, it was the dimmest star known.

Because Proxima Centauri is very faint, we need a telescope to see it. It is also a flare star, which means it sometimes shines much brighter very quickly. In 2016, scientists saw the biggest flare ever from this star. The New Horizons spacecraft took pictures of Proxima Centauri in 2020, showing how it looks from different places.

Future exploration

Proxima Centauri is the closest star to Earth after the Sun. This makes it a good place for future space travel. With today's technology, a spacecraft would take thousands of years to get there. But new ideas, like Breakthrough Starshot, might help. These tiny space probes could travel very fast and reach Proxima Centauri in a few hundred years. They could take pictures and learn about any planets there. It would still take over four years for the information to come back to Earth.