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February 2017 - Proxima b = Water World?
Report #24 - January 2017
Earth Number Two?
The search for another planet like Earth may finally be over. Scientists believe they have discovered an exoplanet orbiting Proxima Centauri, the closest star to our own, that could be habitable.
Proxima Centauri
It all started with several observations made by the European Southern Observatory of the red dwarf star, Proxima Centauri, for a program known as the Pale Red Dot campaign. ESO scientists noticed the star "wobbling" through noting the changing variations of its light, which revealed whether the star was moving towards or away from Earth. The only cause of these fluctuations had to be from the prescence of a planet orbiting the star, gravitationally tugging on the star. It is through these wobbles that ESO astronomers were able to learn about this exoplanet without even seeing it.
Meet Proxima b
ESO scientists named the planet, Proxima b. While this exoplanet seems like a promising candidate for housing lofe, it is a far cry from being like Earth. Here's why:
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Proxima b is believed to be 1.3 times the size of Earth
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Promixa b is extremely close to its star, located 4.3 million miles from it, 5 percent of the distance from the Earth to the Sun
- Proxima b's orbit around its star only takes a short 11.2 days (one eighth that of Mercury's orbit), making it unlikely that the planet has any seasons and affecting its climate so that it is "very different" than Earth's
- Proxima b's close distance to its star would "blast" the planet with far more radiation than Earth
This animation is artist's impression of Proxima b in respective to its star, Proxima Centauri.
Credit: ESO/M. Kornmesser
It may seem impossible that such a planet that close to its host star can house any life at all, but the answer is in the fact that Proxima Centauri is a cool red dwarf star. These type of stars are smaller and fainter than our Sun, allowing a planet to still contain liquid water and have a very close orbit to it, and it just so happens that Proxima b's location from Proxima Centauri is the most ideal for liquid water to exist on its surface. The first step in determining whether or not a planet is habitable is if it can support liquid water, and Proxima b may just pass the test. If it does, astronomers believe that water would most likely be present in "regions that are always facing the Sun or along some kind of tropical belt," according to a recent article released by The Verge.
An artist's interpretation of Proxima b's surface.
Credit: ESO/M. Kornmesser
What's the Next Step?
The next step to determing whether or not Proxima b is a true candidate for housing live and liquid water is to find out the composition of its atmosphere. Doing so will allow scientists to conclude if the planet contains the essential gases for life in the first place, such as nitrogen, hydrogen, and oxygen. Imaging Proxima b is the only way scientists can begin to decode the planet's atmosphere, but, because of its super close vicinity to Proxima Centauri, it would be difficult to nearly impossible to get a clear image of the planet without capturing all of Proxima Centauri's light. Hence why scientists are looking into using a laser in order to send a spacecraft to Proxima b, a process that would take a short 20 years compared to modern propulsion, which would take more than ten thousand years to reach the exoplanet.
Until then, Proxima b will continue to remain at the top of the list for potential habitable planets, a reminder to never rule out the possibility that life could exist beyond Earth.