Space

Potentially habitable planet discovered just 4 light-years away

Potentially habitable planet d...
Artists impression of the view from the surface of Proxima b
Artists impression of the view from the surface of Proxima b
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Artists impression of the view from the surface of Proxima b
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Artists impression of the view from the surface of Proxima b
ESO graphic displaying the distances to Earth's closest stars
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ESO graphic displaying the distances to Earth's closest stars
Graphic displaying the size of Proxima Centauri compared to nearby stellar bodies
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Graphic displaying the size of Proxima Centauri compared to nearby stellar bodies
ESO graphic displaying the location of Proxima Centauri in the southern sky
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ESO graphic displaying the location of Proxima Centauri in the southern sky
Scale of the Proxima Centauri system compared to that of our solar system
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Scale of the Proxima Centauri system compared to that of our solar system
Annotated shot of the sky around Proxima Centauri
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Annotated shot of the sky around Proxima Centauri
Graphic displaying how large Proxima Centauri would appear from the surface of Proxima b, compared to the size of the Sun from Earth
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Graphic displaying how large Proxima Centauri would appear from the surface of Proxima b, compared to the size of the Sun from Earth
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A team of astronomers has discovered clear evidence of a potentially habitable Earth-sized planet orbiting the closest star to our solar system, Proxima Centauri. This newly discovered world, which lies only four light-years from Earth in the direction of the constellation Centaurus, will become a key target for missions searching for life beyond the nurturing influence of our Sun.

Proxima Centauri is classified as a red dwarf. Considered to be relatively small and cool compared to our own Sun, red dwarfs are the most common form of star populating the Milky Way. Despite their diminutive nature, it is thought that planets orbiting in the habitable zones (HZs) of red dwarfs are capable of sustaining life.

A HZ is essentially a region of space surrounding a star in which an orbiting rocky planet can maintain liquid water on its surface. Since water is thought to be one of the key ingredients for the evolution of life, Earth-sized planets orbiting in these regions are a prized target for astronomers looking for extraterrestrial life. The HZ of a red dwarf is much closer to the star's surface when compared to that of a stellar body such as our own Sun.

The discovery of the exoplanet, which has been named Proxima b, was made thanks to an international effort known as the Pale Red Dot campaign. Named in reference to the reddish hue of light thrown off by Proxima Centauri, and as a tribute to CarlSagan's moniker for Earth as the "pale blue dot," the campaign was formed to keep an eye on our Sun's closest neighbor, in the hope of spotting an orbiting Earth-like exoplanet.

Graphic displaying the size of Proxima Centauri compared to nearby stellar bodies
Graphic displaying the size of Proxima Centauri compared to nearby stellar bodies

For the first half of 2016, Proxima Centauri was regularly monitored by a host of observatories spread across the globe. These telescopes, including the ESO's 3.6 m (11.8ft) telescope located at theLa Scilla observatory, Chile, were searching for minute wobbles that would serve as proof that the red dwarf was being disturbed by the gravitational influence of an orbiting exoplanet.

The first detection of Proxima b occurred in 2013, however the evidence was not sufficient to clearly point to the existence of the exoplanet. The intensive observations carried out in 2016 under the Pale Red Dot effort were more successful, providing clear evidence that the star was indeed wobbling through space. At points, the red dwarf was observed traveling back towards Earth at a rate of 5 km per hour (3.1 mph), and then away from our planet at the same pace. This cycle continued once every 11.2 days.

An analysis of the 2013 readings in conjunction with the Pale Red Dot observations of Proxima Centauri's wobble and light signature, provided clear evidence for the existence of Proxima b. It is estimated that the exoplanet has a mass 1.3 times that of Earth, and orbits its star at a distance of 7 million km (4.3 million miles), placing it well inside the HZ of a red dwarf star.

Graphic displaying how large Proxima Centauri would appear from the surface of Proxima b, compared to the size of the Sun from Earth
Graphic displaying how large Proxima Centauri would appear from the surface of Proxima b, compared to the size of the Sun from Earth

"I kept checking the consistency of the signal every single day during the 60 nights of the Pale Red Dot campaign" commented Dr Guillem Anglada-Escudé, one of the lead astronomers behind the Pale Red Dot campaign hailing from Queen MaryUniversity, London. "The first 10 were promising, the first 20 were consistent with expectations, and at 30 days the result was pretty much definitive, so we started drafting the paper!"

So, could this newfound planet, which orbits its star at only 5 percent the distance between the Earth andSun actually be habitable? Ultimately, we do not yet know. It is estimated that the surface temperature is conducive to the presence of liquid water, but that the environment may have been radically altered from anything we know here on Earth as a result of its disparate formation history, and the intense radiation pouring out from the nearby red dwarf.

Furthermore, it is possible that the planet is rotationally locked to its star. This means that one face of the world is bathed in perpetual daylight, and the other in constant night. According to one of the papers published on the discovery of Proxima b, if the exoplanet were to be rotationally locked, liquid water would likely only exist on the side bathed in sunlight. If the exoplanet's orbit is not locked, then it is thought that water could only endure in a tropical belt.

Scale of the Proxima Centauri system compared to that of our solar system
Scale of the Proxima Centauri system compared to that of our solar system

There are numerous reasons that have been given as to why life could not evolve on the planet. It has been suggested that Proxima b does not experience seasons, and that the atmosphere could be fundamentally different to our own, assuming that it hasn't evaporated away into space. On the bright side, none of these doom-and-gloom scenarios can be proven without direct observation of the planet, and this can only occur in the unlikely event that the exoplanet passes between Proxima Centauri and Earth.

Although it is extremely doubtful that this will happen, current and future Earth-bound and orbital telescopes will watch for just such an occurrence, which would allow astronomers to glean an understanding of the composition of Proxima b's atmosphere.

Scroll down to view a fly-through of the Proxima Centauri system.

Source:European Southern Observatory

A fly-through of the Proxima Centauri system

View gallery - 7 images
5 comments
VincentWolf
Time to call the Enterprise for a little visit.
Don Duncan
4 light years away? Doesn't that mean it would take 8 years to receive a "call back"?
Lbrewer42
QUote: "...Since water is thought to be one of the key ingredients for the evolution of life... ." And as soon as just ONE example of a creature changing from one species to another - not just filtering out an genetic expression from the gene pool it already originates from, we will have the very first data showing different kinds of animals can propagate from one root. In factual science, we have never witnessed an organism moving from one gene pool to another. Archaeopteryx was once heralded as the first missing link. It is now accepted as simply a bird with teeth. But Shhhh! This fact goes against the mainstream money flow. Welcome to the modern Dark Ages.
ChecMate
Yes Don, it would take 8 years at our current technology (speed of light) to receive a 'call back', but using a newer found form of communication ( Quantum Entanglement) this would be instantaneous!
TheAnalyst
The idea to search for an alternate planet for future habitat is simply stupid, no matter who proposes it. Here, we have a highly habitable and adapted planet. We are spending billions in searching for a habitable planet, while we may need fraction of cost to make this planet healthier. We only need to mend our habits to keep this plane perfectly habitable. We need to adopt ourselves to the climate, not change our ambiance to suit us. In the process of mending the ambiance for few million spoiled entities we are keep in life of 6 billion in danger and on the path to no where. Here we are not able to design mass transit system for our cities and there we are planning to relocate to a light years away planet. Will we be in position to relocate 6-7 billion people to such a planet even if close to the last planet in our solar planet in at least thousand years. We American are now just capable of sending our astronauts just outside Earth with high mortality risk. After the 1969's so called moon landing we were not able to send a human again on Moon since 1972. I just cannot understand the logic of even entertaining such thought. It is highly PRACTICAL AND RATIONAL to improve habitability of the planet we are born in and inherited rather than going beyond the Exosphere. It does not need scientist. PERIOD.