Late last month the European Southern Observatory, or ESO, announced they found an exoplanet orbiting Proxima Centauri. An exoplanet is a planet found outside our own solar system. The planet found will be called Proxima B. We have been finding exoplanets since 1988, and have since then found over three thousand exoplanets. So a question is raised: what makes Proxima B’s detection a significant and important one? Locating it was remarkable. It was made by watching the small movements that the star, Proxima Centauri, makes as Proxima B’s gravity pulls on Proxima Centauri during orbit. Unlike most other exoplanets we have found, it could not be located by looking for a slight dimming as the planet passes in front of the star. This is because Proxima B does not pass in front of its star from our perspective.
One thing that makes this exoplanet special is its distance from our own solar system. Its parent star, Proxima Centauri, is about 4.2 light-years or about 25 trillion miles away from Earth. Although this is still incredibly far, all hope should not be lost. There is still a good opportunity to learn a great deal about this exoplanet.
This brings us to Proxima B’s amazing features, starting with its size. Most exoplanets we have found in the past have been very large and are comparable to the large gas giants in our own solar system. But Proxima B is much smaller and is only slightly more massive than Earth. It is also moving very quickly around its host star, completing a full orbit in around 11 days - much shorter than Earth’s 365-day orbit. The next important thing to note is the type of star Proxima B, is orbiting. Proxima Centauri is a red dwarf. Red dwarves do not produce much energy when compared to a star like the Sun. This allows Proxima B to be very close to its star. Its average distance from Proxima Centauri is 5 million miles. This is small in comparison to the 93 million miles Earth is from the Sun, but even at this small distance from its host star, it is still in the habitable zone. The habitable zone is a range of orbits that a planet could have where you could reasonably expect it to be a suitable temperature to have liquid water. This makes Proxima B a great candidate for searching for evidence of life out in the universe and it will surely become the focus for many professionals in the field of Astrobiology.
The Proxima Centauri system has always been thought of as one of the first possible destinations for exploration outside our own Solar System. We may send deep space probes, and possibly one day, people there; although sending people is still a long shot. However, there has been some talk of an initiative called the Starshot Program, which has plans to send probes that would arrive at Alpha Centauri, a neighboring star not far from Proxima Centauri, within our lifetime, so also sending them to Proxima Centauri would not be out of the question. If we were able to do this, we could learn more about the exoplanet Proxima B than we have learned about any other exoplanet in the past.
Proxima B’s greatest quality will be our ability to learn about Earth’s formation and the start of life from it. If learning from Proxima B is all we are ever able to accomplish, then it will have served a greater purpose than I think we will ever realize.
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