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How big is the Distance from the Sun to Proxima Centauri?

40 billón kilómetros!

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Distance from the Sun to Proxima Centauri

Proxima Centauri is the closest known star to the Sun as of 2026, and the distance between them is about 40 trillion kilometers. That is about 4.2 light-years, where a light-year is the distance light travels in one year, about 9.46 trillion kilometers. Earth is so close to the Sun by comparison that the distance from Earth to Proxima Centauri is almost exactly the same.

Distance

Astronomers measure the distance to nearby stars by parallax. As Earth travels around the Sun, a nearby star seems to shift slightly against the much more distant stars behind it. Measuring the star's position six months apart, from opposite sides of Earth's orbit, gives the size of that shift, and from it the distance. Even for Proxima Centauri the shift is less than one arcsecond, which is 1/3,600 of a degree.

The European Space Agency's Gaia spacecraft measured the positions of nearly two billion stars and other objects between 2014 and 2025. Its third data release gives Proxima Centauri a parallax of 0.768 arcseconds, which puts the star 1.302 parsecs away. A parsec, about 3.26 light-years, is the distance at which the average distance between Earth and the Sun would span an angle of one arcsecond. Gaia's figure works out to 40.17 trillion kilometers, or 4.25 light-years.

An earlier measurement, used in a 2017 study of the star's orbit, gave 1.3008 parsecs, less than 0.1% shorter. The distance is also slowly shrinking. Proxima Centauri is moving toward the Sun at about 22 kilometers per second, which brings it about 700 million kilometers closer each year, a tiny fraction of the whole distance.

Size comparisons

  • The distance is about 270,000 times the average distance from Earth to the Sun.
  • It is about 1.3 parsecs, the unit astronomers usually use for distances within the Milky Way.
  • The Helix Nebula, the next larger object in the explorer, is a cloud of gas about 5.3 light-years across, so this distance is about four-fifths of its width.
  • If the Sun were shrunk to the size of a basketball, Earth would be about 26 meters (85 feet) away from it. Proxima Centauri would be about 6,900 kilometers (4,300 miles) away, a little more than half the width of Earth.
  • Light, which travels about 300,000 kilometers per second, takes about 4.2 years to cover the distance. Voyager 1, which in 2024 was the farthest human-made object from Earth, travels at about 17 kilometers per second, and at that speed the trip would take about 75,000 years.

A star in a triple system

Proxima Centauri is a cool red dwarf, a star much smaller and fainter than the Sun. It is too faint to see with the unaided eye, and it was discovered only in 1915.

It is the smallest of three stars that travel through space together. The other two, Alpha Centauri A and Alpha Centauri B, orbit each other about 4.37 light-years from the Sun, a little farther away than Proxima. A 2017 study found that Proxima is held by the pair's gravity. It lies about 13,000 times the Earth–Sun distance from them and takes about 550,000 years to circle them once.

Sources

La Escala del Universo > Distance from the Sun to Proxima Centauri

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