Just over four light years away, a planet orbits its cool red-dwarf star – Proxima Centauri, the sun’s closest star neighbour. What is special about this planet is that after years of tracking it, astronomers have come to the conclusion that it is in the habitable zone of its star.
Informally designated Proxima b, the planet revolves around its star once every 11.2 days and is located at a distance of nearly 7 million kilometres from its star. This is only about 5 per cent the Earth-Sun distance. The mass of the planet is believed to be about 1.3 times that of the Earth. It could contain water and it is estimated that surface temperatures could be close to – 40 degrees C.
Put together, all these factors hint at the tantalising possibility that Proxima b can support life or is habitable.
The first exoplanets were spotted in 1995, and today there are over 3,000 known exoplanets. Yet this system is special for being close and lending itself to easy observation.
The star Proxima Centauri is about 4.2 light years away from the sun – a distance that it would take 4.2 years to traverse if you were travelling at the speed of light – a fact that looks very attractive when contemplating interstellar travel.
The star, Proxima Centauri, is not very bright and cannot be tracked with the naked eye, especially as it is very close to the brighter binary star pair Alpha Centauri AB.
Red dwarfs such as Proxima Centauri can also vary in brightness which can mislead the observer into thinking they are observing a planet. This possibility was ruled out by monitoring its changing brightness carefully.
Astronomers also deduce that its climate would be markedly different from the Earth’s, due to its manner or rotation – it appears unlikely the planet will have any seasons.