Science & Technology

Proxima B: Neighbouring Planet in the Cosmic Sweet Spot

Proxima B orbits our nearest star
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It’s what astronomers and comic-conners have been waiting to hear for decades: an Earth-like planet has been discovered within travelling distance from Earth; orbiting our nearest star, Proxima Centauri.

This planet, dubbed Proxima B, has been discovered on the back of 16 years analysis of Doppler signal data initiated by the Pale Red Dot Campaign based at the European Southern Observatory in Chile. In other words, the researchers have been closely monitoring ‘light-wobbles’ which result from “the periodic stretching and compressing of the light from Proxima Centauri due to the motion induced on it by the planet”.  [Hugh R. A. Jones, 2016]

As our closest neighbouring star outside our own solar system, Proxima Centauri resides at a mere 4.37 light-years away [that’s 41,343,392,165,178 km]. With current technology, it would take us centuries to reach it but there are already plans in place to send a small probe out which could reach the exoplanet within 20 years. Nobel-prize-winning physicist, Stephen Hawking, alongside Russian billionaire, Yuri Milner, have developed Project Breakthrough Starshot which aims to send a gram-scale nanocraft, on a sail pushed by a light beam to the Alpha Centauri star system. It is also within our engineering capabilities to build telescopes that could observe Proxima B now.

Proxima B - a nearby terrestrial planet?

Artist’s representation of Proxima B

 

A common red dwarf star, Proxima Centauri is smaller and cooler than the sun and therefore burns longer. Formed just like any other star; clouds of dust and gas pulled together by gravity which then starts to rotate. Once the critical temperature is reached, the fusion commences – and light is emitted!

Proxima B sits in the ‘Goldilocks zone’ around Proxima Centauri – that cosmic sweet spot where life has the potential to thrive.

The search for life often begins with the search for liquid water – where water can exist, life can survive. We reside happily at 149.6 m km from our sun (an average-sized main-sequence star) – this is a good distance for a star as big and hot as our sun. Proxima B lies at 7.5 m km away from Proxima Centauri – the ideal distance from this cooler and smaller red dwarf star.

Although bigger than Earth, Proxima B is still relatively small in planetary terms which indicates that it could have a rocky composition as most gas planets would be larger. Due to its propinquity to its star, Proxima B has a rapid orbit of 11.2 days and potentially it could be in tidal lock with Proxima Centauri (in the same way that the Moon is with the Earth). This would indicate that Proxima B does not rotate which may preclude an uneven atmosphere and leave a dark side which would be less habitable and somewhat gloomy.

So far research has indicated that temperatures would average -40C (comparable to our own terrestrial temperatures). This is where our atmosphere comes into play by absorbing and retaining heat from the sun which allows us to maintain our balmy temperatures. If Proxima B also has an atmosphere, the temperatures would be highly comparable to Earth.

The biggest argument against habitability so far is the high dosage of X-ray radiation that Proxima B is subject to due to its close orbit to Proxima Centauri – approximately 400 times that which is experienced by Earth.

This exciting discovery re-opens the ethical and moral debates surrounding species relocation. If Proxima B is habitable for mankind – would we relocate there if Earth became inhabitable due to climate change, or eventually, heat from an expanding sun?

If we relocate due to destroying our planet by anthropogenic global warming, it is debatable whether this would be a just choice. Humanity is certainly not known for its ability to learn from its mistakes – it would be a high risk to presume that we could treat another planet with more love and care than our current one. Surely, if we ruin one planet, we cannot be responsible for another – we would simply be galactic parasites.

On the other hand, regardless of our own destructive tendencies, the expanding sun will eventually make life on Earth impossible (billions and billions of years into the future) so perhaps a viable alternative is fair game. Unless, intelligent life is already present on Proxima B – in which case, it is not our decision. But perhaps if we ask nicely, they will share with us.

 

References:

 “A Terrestrial Planet Candidate In A Temperate Orbit Around Proxima Centauri”. Nature(2016): n. pag. Web. 24 Aug. 2016.

Daley, Jason. “Stephen Hawking And Billionaire Announce Project To Send Tiny Probes To Nearest Star System”. Smithsonian. N.p., 2016. Web. 24 Aug. 2016.

How Does Our Sun Compare To Other Stars? :: NASA Space Place”. Spaceplace.nasa.gov. N.p., 2016. Web. 24 Aug. 2016.

Jones, Hugh R. A. “The Doppler Method And Proxima Centauri”. PALE RED DOT. N.p., 2016. Web. 24 Aug. 2016.

The Doppler Method And Proxima Centauri”. PALE RED DOT. N.p., 2016. Web. 24 Aug. 2016.

Red Dwarfs: The Most Common And Longest-Lived Stars”. Space.com. N.p., 2016. Web. 24 Aug. 2016.

 

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