A certain Mr Hawking is well known for speculating that if the Human race is to survive into the future we must “take to the stars”, finding a new planet on which to settle down upon and start a new life, repeating this process until the end of time. However this leaves us with the problem of where to move too, obviously no planet in the solar system is able to support human life, ergo we must look further expanses of space. Presented are a few of the most likely candidates, providing most of the necessities to human life, although unreachable with today’s modern space travel methods.

OGLE-2005-BLG-390Lb

On August the 10th 2005, in Chile, a new exoplanet was discovered, and given the snappy title of OGLE-2005-BLG-390Lb. This was a groundbreaking discovery, with the planet being more similar to earth than any planet discovered to date.

OGLE-2005-BLG-390Lb is located close to the centre of the Milky Way galaxy in the Scorpio constellation, around 25,000 light-years away from Earth.

 The planet is about five times larger than the earth (although it was the smallest exoplanet ever found orbiting a star in 2005) and lies three times as far from its star as the Earth does from the sun. As opposed to our sun, the sun around which the planet orbits is expected to be a red dwarf (95% probability), which it completes a full orbit around approximately every 10 years.

Geologically the Planet is expected to be similar to the earth, having a similar rocky core, and have a thin atmosphere, with frozen volatiles such as water, ammonia and nitrogen being present on its surface, due to its cold planetary temperatures (-2200c). However it is possible that it could resemble an icy gas planet similar to Uranus, albeit a much smaller version, which would obviously lower its suitability to sustain human life. However even the first scenario means it is not directly suitable to uphold human life due to freezing temperatures, although if water is present (even if only in ice form) in theory through modifying characteristics (Terraforming) like the planets atmosphere the planet could become habitable.

Gliese 581c

Gliese 581c was discovered in Switzerland on 4th April 2007, located towards the Libra constellation around 20.5 light-years away from the Earth.

Although its mass is estimated to be around five times greater than that of earth it is not greatly bigger, being an estimated distance of 12,000 miles across (whereas Earth is 8000 miles pole to pole). The planets orbits 11 millions km away from its sun (Gliese 581), taking only 13 days to complete a “year”.

The planet is estimated to have a gravitational strength of about double that of the Earth, meaning a thick atmosphere is probable, and if oxygen or methane are proved to be present this may even indicated life is present already.

With moderate temperatures of 0-400c the planet is expected to contain liquid water in abundant quantities, which could result in a nearly surface wide ocean, with the only a few rocky islands and icebergs being the only form of land. However the presence of water along with the probability of a substantial atmosphere makes it a prime candidate for life.

Due to its distance it is also possible that if any inhabitants also had our level of technology they would be able to faintly pick up radio signals that have been sent out to space by our strongest military transmitters. On the discovery of this planet Williams Hill said it had shortened the odds on proving the existence of extraterrestrial intelligence from 1,000-1 to 100-1.

Alpha Centauri

Although not an individual planet the Alpha Centauri star system is the closest to our solar system, being located only 4.37 light years away from our sun, meaning that it is likely to be the first star system to be visited if interstellar travel ever becomes possible.

Although there is no definite proof that a suitable planet exists in these systems numerous computer programmes have predicted the formation of small, rocky, earth like planets have formed around the Alpha Centauri B planets. Some of which would be able to maintain life.

Standing on such a planet one would not only see the main star Alpha Centauri B, which is slightly smaller and less luminous than our sun, but a “secondary” sun, being Alpha Centauri A, which is larger and more luminous than our sun, although due to its distance being dimmer than Alpha Centauri B, although still many times brighter than our moon.

Other Planets

Hundreds of exoplanets have been discovered, although many are unsuitable for maintaining life, for a number of reasons, either due to size, temperature or composition (i.e. we cannot live on a planet made of gas). Also none of the planets we have deemed “suitable” to maintain life are not definitely able to, and cannot be proven with current levels of technology. Also many of the smaller planets that surely exist remain undiscovered, with detecting their spectral signatures being likened to finding a firefly in a searchlight, as the stars radiation greatly overpowers the smaller planets. However luckily for the human race the need for changing planets is not in the foreseeable future.

I do hope this article has provided an interesting and informative read; feel free to comment any suggestions or questions, which I will try to respond to.