Image Credit: Axel Mellinger

Whenever a new exoplanet discovery is announced, some of the excitement is marred by the true fact that space is so incredibly large, it's very unlikely that we'll ever be able to venture to any of these far-away, exotic worlds. All of that changed back in 2012, when, after years of searching, astronomers from the European Southern Observatory detected an exoplanet located in Alpha Centaurithe triple-star system that makes up one of the brightest points of light in our sky, and more importantly, is home to our nearest celestial neighbors! 

Two of the stars,  which can be found about 4.3 light-years from Earth, dubbed Alpha Centauri A and B (respectively) are both medium-mass stars that share many of the same characteristics as parent star (including age, size, mass and composition). The primary stars in the system are separated by a distance of about 11 AU (that is 11 trips from the Earth to the Sun and back), which equals out to the distance Uranus is from the Sun. The third is a slightly smaller, dimmer and more distant star, known as a red dwarf. Whereas, the primary stars are relatively close-by, Promima Centauri is about 13,000 AU's from the main stellar duo.


For a long time now, astronomers from space agencies across the globe have studied the system, looking for tell-tale signs indicative of an orbiting planet. Studying the starlight leads to understanding the composition of the stars in the system and others like it. Stars that appear to be anemic (containing less iron) may allude to the presence of a rocky world. Such a planet would have used up a small, but noticeable fraction of the heavy elements present in the protoplanetary disk enveloping young stars. This method may be one of (if not THE) best circumstantial evidence of terrestrial planets like Earth!

Credit: ESO/L.Calcada

Other than being able to single out the stars most capable of having orbiting rocky worlds using the stellar fingerprinting method, finding an exoplanet in the Alpha Centauri system is a groundbreaking revolution. The planet, is approximately 1.13 times more massive than Earth -- is one of the least massive exoplanets discovered to date. This brings us just a smidge closer to finding THE Terra Nova...another planet in the galaxy with similar mass and composition to Earth, circling a sun-like star in the goldilocks region where water may exist in liquid form. Statistically speaking, there should be MILLIONS of them scattered throughout the Milky Way alone! Many of the parent stars of these potential planets may be around the same age as our Sun.

The planets in the planetary system may have evolved in a similar time frame as our solar system did...bringing about the possibility that any microbial life that exists on the planet may have had several billion years for said life to evolve into multi-cellular organisms...possibly even into semi intelligent beings (such as ourselves).

Speaking of ideal conditions, this planet is much too hot to sustain life. Alpha Centauri B is slightly cooler than the sun, but the exoplanet has an orbital period of about 3.24 days, which indicates the planet may be as close as 4 million miles (6 million km) from the star. In comparison, Mercury's elliptical orbit takes it between 29 million miles (46 million km) and 44 million miles (70 million km) from the sun. More information must be unlocked about the planet in order to pin down a precise estimate of the surface temperatures on the rocky planet.


Distance to Alpha Centauri visualized

One last thing... though this system is VERY close-by (in cosmological distances), it's still pretty far away. It would take light traveling at maximum speed over 4 years to reach the Alpha Centauri system, but for humans... traveling at the maximum speed of 17,600 mph (28,300 kph) it would take hundreds of thousands of years (165,000 to be exact) using current technology to arrive to the triple star system, which are about 25 TRILLION miles away.

The voyager probes that launched in the late 1970s have barely even been able to escaped from the outer region of our solar system. In fact, it would take some 296,000 years for Voyager 2 to pass within 4.3 light-years of Sirius, the brightest star in our night sky. If you could imagine the planet Earth as a grain of sand, Alpha Centauri would be over 10 kilometers – or about 6 miles – away. So it appears we're stuck here for the foreseeable future, but that doesn't taint the awesomeness of this discovery.

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