The search for exoplanets has been very fruitful over the past few years, with thousands found to be dotting the skies beyond our solar system. In 1992, no planets were known other than those orbiting the sun, but the hunt for planets outside our space pen has led astronomers to believe that the galaxy is full of them.
Little evidence has surfaced yet to point towards any semblance of life on far-flung planets, but a huge leap forward has been taken in the exploration. The latest discovery means the search for Earth-like planets – and consequently life – may not need to take place hundreds to thousands of light years away; rather, a knock on the door of our closest cosmic neighbour may just do the trick.
Long a muse of science fiction writers, Proxima Centauri, the sun’s closest stellar counterpart, has now become the star at the centre of astronomers’ attention with the finding of a new, Earth-like exoplanet orbiting it.
Part of the Alpha Centauri star system, Proxima Centauri is the sun’s equivalent of a next-door neighbour. It is a star that has been studied in detail and can be found in the southern constellation Centaurus, glowing with a pale red light. As a result, it is known as a red dwarf – a term for the smallest, coolest known stars. The majority of stars close to the sun are thought to be red dwarfs.
In comparison to our sun, which can burn at temperatures as high as 15m degrees Celsius, Proxima Centauri reaches little more than 2,700 degrees Celsius. It has a mass of around 12 per cent of the sun, making it, on the surface, a star unlike our own. This raises questions about how any possible planet orbiting Proxima Centauri could harbour life.
The exoplanet found by researchers has been called Proxima b, and based on the conditions scientists believe are required for a planet to station life, Proxima has a great deal of potential. It is thought to be at least 1.3 times the mass of Earth, have a year that lasts 11.2 days and sits much closer to its star than Earth does.
Despite being much hotter than Proxima Centauri, the sun is 91 million miles away from Earth. In comparison, Centauri b is a mere 4.5 million miles away from its star. The proximity of Centauri b to Proxima Centauri means that despite the star’s coolness, the planet is comfortably seated in the “Goldilocks zone” – a region not too far from, nor too close to a star, a region which could make any planet it hosts habitable as liquid water could be running on its surface.
The researchers who made the observations published their results in the journal Nature, making clear just how exciting the findings are. Speaking to the journal, Guillem Anglada-Escudé, astronomer at Queen Mary University and leader of the research team that made the discovery said: “The search for life starts now.”
To find the planet, Anglada-Escudé and his team spent 54 days making observations with a telescope in Chile. The telescope is built to detect wobbles in starlight which result from the gravitational pull of a planet being in effect when passing by its star in front of the telescope. Picking up on these wobbles is what allowed the scientists to discover the presence of the planet and its attributes.
Research in the exoplanet field is moving, and it’s moving rapidly. In July 2015, Nasa scientists and astronomers at the Harvard-Smithsonian Centre for Astrophysics believed that “six percent of red dwarf stars have an Earth-sized planet in the habitable zone” and the closest exoplanet worth exploring was 13 light years away. Earlier this year, Nasa’s Kepler Space Telescope confirmed the discovery of 1,284 exoplanets, doubling the number of planets previously thought to exist. Of the 1,284, nine were found in the Goldilocks zone.
As promising as the research is, any hopes of reaching the planet in the near-future should quickly be abated. Proxima Centauri is 4.2 light years (approximately 25 million miles) away from our planet, which, on a space scale, is tiny. That tininess, however, does not translate over well to ease of travel to the star, as a spacecraft travelling at 20 per cent the speed of light would still take more than 20 years to reach its destination.
Venture capitalist Yuri Milner announced earlier this year that he was making a foray into the business of space travel and hopes to develop a spacecraft which uses lasers to propel itself. It would make travel far faster and aid exoplanet research tremendously. He has gained support from the likes of Stephen Hawking and Mark Zuckerberg in an initiative called Breakthrough Starshot. It’s the type of technology that would be required to get to Proxima b in less than two to three decades.
The researchers who discovered Proxima b seem to be a little more realistic in their expectations of reaching the planet, but maintain optimism, stating that there could be a planned “robotic exploration in the coming centuries.”
As limited as we may be in reaching the star and planet with current technology, the excitement surrounding the discovery is primarily driven by just how close Proxima b is. A great deal of information can be gathered to determine the environmental makeup of the planet’s atmosphere. Unless we miraculously stumble upon a star closer to our solar system than Proxima Centauri, Proxima b is probably going to be our best bet for interstellar travel, as it is the next destination on the cosmic freeway.
The painstaking efforts of astronomers to find Earth-like planets and potential life in space are promising. As Proxima Centauri and Proxima b become central sites of exoplanet research, our first point of contact with life in the universe may just be at our doorstep.