Fancy jetting off somewhere new and exotic for your holidays this year? How about the newest, most expensive option out there?
Proxima b is your newly discovered, closest neighbouring habitable planet. Only 4.25 light years away, this rocky planet orbits our nearest star, Proxima Centuri. With a mass 1.3 times that of Earth, and a surface temperature which may, hopefully, if there’s an atmosphere, allow liquid water oceans to form, this planet may just be visit-able. A year long holiday on this planet is the perfect length – it lasts only 11.2 Earth days, excluding the 70,000 years of travel on modern spacecraft each way.
Okay, so the average surface temperature could be anything from -33°C to the high hundreds, depending on whether there is an atmosphere (and its nature if there is one), and since the planet and star are tidally locked only one side ever sees its sun, which appears as a dull red glow three times the size of Earth’s sun (Proxima Centuri is a red dwarf, meaning it is small and burns less brightly than our sun). And yes, if there isn’t an atmosphere the bursts of ultraviolet and X-ray radiation regularly emitted from Proxima Centuri would kill you, but there’s a small chance that the atmosphere and magnetic field will be just right to protect you, and to ensure that the heat from the planet’s star is distributed evenly over the whole planet, allowing you to holiday in style.
The planet was first spotted in 2013, when astronomers saw signs of a small gravitational pull exerted by the planet on its star. It could just be a random blip in the data that they collected, but the scientists spent weeks trying to explain the signal away, testing whether it may have been caused by noise in the measurement or the star’s own activity. Convinced that the mystery couldn’t be resolved that way, they checked the data from other telescopes, and started searching further in their ‘red dot campaign’. Only a third of the way in to their 60 planned nights of data collection, the team were convinced – the new planet is there.
Apart from the planet’s mass, and the fact that it orbits the star 7.3 million km away from it (a mere 5% of the distance between the sun and Earth), we don’t know much about this new planet, which they named Proxima b. Some scientists want to send a probe to the planet. Indeed, a project, known as Breakthrough Starshot, already exists for this purpose, but it only has $100 million of the billions of dollars of funding it would need to get there. Failing that, we will be able to find out more about the planet if it passes between its star and us, in an event called transit. In the unlikely event that this does happen, we may be able to use the Hubble telescope to see features in Proxima b’s atmosphere, by analysing the light which passes through.
If that’s not good enough though, don’t worry too much. In 2024, the European Extremely Large Telescope, or E-ELT to its friends, is due to be built. This 40 meter wide telescope might manage a whole pixel image of the planet. Pretty disappointing, but astronomers reckon that monitoring how the pixel changes over time might be able to tell us about the cloud patterns or even continents of the planet. Alternatively, the James Webb Space Telescope, due to replace the Hubble in 2018, might be able to tell us something.
For now, the planet is a bit of a puzzle – it’s unlikely to have formed so close to the star, so how did it get there? What we do know, though, is that you might not want to start packing just yet.
Guillem Anglada-Escudé, Pedro J. Amado, John Barnes, Zaira M. Berdiñas, R. Paul Butler, Gavin A. L. Coleman, Ignacio de la Cueva, Stefan Dreizler, Michael Endl, Benjamin Giesers, Sandra V. Jeffers, James S. Jenkins, Hugh R. A. Jones, Marcin Kiraga, Martin Kürster, Marίa J. López-González, Christopher J. Marvin, Nicolás Morales, Julien Morin, Richard P. Nelson, José L. Ortiz, Aviv Ofir, Sijme-Jan Paardekooper, Ansgar Reiners, Eloy Rodríguez, et al., Nature, 536, 437–440, 24th August 2016, doi:10.1038/nature19106 (accessed 29/08/2016)
Jacob Aron, New Scientist Vol 231 No 3088 pg 8, 27th August 2016, ‘The Earth Next Door’(https://www.newscientist.com/article/mg23130884-100-proxima-b-closest-earth-like-planet-discovered-right-next-door/)
Nicola Davis, The Guardian, 24th August 2016, ‘Discovery of potentially Earth-like planet Proxima b raises hopes for life’, https://www.theguardian.com/science/2016/aug/24/earth-like-planet-found-orbiting-our-suns-nearest-star-raises-hopes-for-life-proxima-b (accessed 29/08/2016)