In Douglas Adams’ “The Hitchhiker’s Guide to the Galaxy” (T) Alpha Centauri is a very important place in the Universe. There you can find the Local Planning Department, where you can learn about the local affairs and make formal complaints should you find, let’s say, that the Earth is to be destroyed to make room for a new intergalactic bypass. But don’t panic! This is not an article to warn you that the Vogons are coming (sorry! too many Douglas Adams’ references to explain)! But there are interesting new discoveries in the region near stars from the Centaurus constellation.
Proxima Centauri is one of the stars of the Centaurus constellation. It is less bright than Alpha Centauri but it is a bit closer to Earth than that star. In fact, Proxima Centauri is the closest star to our planet apart from the sun. Now, scientists have found that there is a planet similar to Earth orbiting that star.
Figure 1. Proxima Centauri is a small star near Alpha Centauri.
To find the planet the scientists studied the data collected by instruments from the European Space Observatory (ESO). They studied the light emitted from Proxima Centauri and realized that the data suggested the presence of a small planet around this star. When a planet orbits a star, the star doesn’t stand still. In fact, both the planet and the star rotate around a point called the center of mass of the system. Therefore it is possible to infer the presence of a planet by observing the motion of a star.
But how can scientists realize that the star is moving, if it is so far away? By looking at the color of the light emitted by the star. Have you ever noticed that there is a difference between the sound made by a car when it is approaching, and when it is moving away from you? This happens because the sound is a wave. The same thing will happen for the light emitted from the star. Light can be thought of as a wave and when the star is moving towards (or away from) the Earth the color of the light is slightly different. This allows the scientists to gather information about the movement of stars even if the stars are not near us.
Figure 2. Scientists found that there is a small, Earth-like, planet orbiting Proxima Centauri.
The planet is small and rocky, with a mass of about 1.3 times that of the Earth. Plus, its equilibrium temperature is such that water could exist in a liquid form in the planet. This means that this is a great candidate for the search of extraterrestrial life. Or, at the very least, it can allow scientists to learn more about the formation of planets similar to ours.
Though there isn’t (hopefully) a plan to build an intergalactic bypass that passes trough Earth, it is still quite interesting to find an Earth-like planet so close to ours, in Proxima Centauri. Soon the scientists will be able to learn more about the formation and dynamics of planets such as our own.
Kellen Manoela Siqueira
The full work can be found in the August 2016 edition of Nature.