The polar ice caps are melting, we are running out of food, fuel and water, and the Amazon is facing complete destruction. We seem deadset on the total and permanent incapacitation of our planet. It’s a bloody lucky thing then that astronomers have just discovered an ‘Earth-like’ planet, a pale red dot, a mere 4.25 light-years away. That’s close enough, right?
Not really. While 4.25 light-years is astonishingly close by intergalactic standards, it is painfully far by human – 40,208,104,508,468 km to be precise. To get there, you’d have to travel at relativistic speeds. By the time you made it back, everyone you knew would be old and wrinkly at best. Think of the end of Interstellar, but with fewer poltergeists and flying books.
The planet, currently named Proxima Centauri b, orbits our closest neighbouring star, Proxima Centauri. This makes Proxima Centauri b perhaps the closest Earth-like planet outside our solar system. ‘Earth-like’ meaning that the planet is similar in weight to Earth and so presumably composed of rock or terrain, rather than liquid or gas. The planet is also within Proxima Centauri’s ‘habitable zone’, which means the surface can support liquid water.
How long will it be until humans are exploring foreign planets?
While we know of about a dozen other planets located in various habitable zones, Proxima Centauri b is the closest. So close, in fact, that it was detected by a telescope only 3.6 metres in length. Proxima Centauri b orbits much closer to its sun than Earth, so if you were to stand on the planet’s surface and look up, it would be approximately three times as big as our own. Surface temperature estimates range from sub-arctic (–33°C) to the Eye of Sauron (>100°C).
So while it seems relatively promising so far, don’t pack your bags just yet. There are a few nagging questions that remain before Proxima Centauri b becomes the tropical holiday centrepiece of the next Price is Right showcase.
To answer these questions, scientists are hoping for a “transit” – where the planet will pass between Proxima Centauri and Earth. This will tell us whether the planet has its own atmosphere, and whether there’s water on the surface. A transit will also allow scientists to determine if there’s oxygen in the atmosphere. Oxygen reacts quickly with other chemicals (if you haven’t repressed high-school chemistry, you might have some familiarity with the concept of “rapid oxidation”, or what is more commonly known as “fire”). If there is oxygen in Proxima Centauri b’s atmosphere then there must be a source: hopefully, life. If the transit does happen, then we can use the ever-faithful Hubble space telescope to compare the light from Proxima Centauri as it passes through and around its planet.
Sadly, the chances of a transit happening are slim, just one in 67. Regardless of whether the transit occurs, we’re going to need a bigger telescope to find out more about this future honeymoon hotspot. There are a few candidates currently in construction. First up, we have the 24.5 m Chilean Giant Magellan Telescope. However, this might not be big enough, and we won’t be able see the dull planet up against the furnace behind it, which is 10 million times brighter. The second potential candidate is the Thirty Meter Telescope, destined for Hawaii.
An artist’s impression of Hawaii’s Thirty Meter Telescope
Unfortunately, Proxima Centauri is in the southern skies while Hawaii is in the north, making things logistically difficult. The third and final contender is the European Extremely Large Telescope (up all night on that one, naming guys?), which is 39 metres across. If you’re having trouble thinking about how big that is, think about the length of an Olympic swimming pool, or the height of the statue of Christ the Redeemer in Rio de Janeiro – some might say, Extremely Large.
When the Extremely Large Telescope is finished in 2024, it will hopefully be able to gather a single pixel of light from the planet. Watching how the light changes will enable an army of boffins to determine if there are clouds or continents on Proxima Centauri b, or take happy snaps of the colony that Tesla’s Elon Musk is undoubtedly plotting this very minute.
So there is hope yet for a brave new intragalactic world. Perhaps not in our lifetimes, but maybe in time to save our great (times 1015) grandchildren from the seemingly inevitable demise of Planet Earth.