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posted by martyb on Thursday August 18 2016, @09:52AM   Printer-friendly
from the that'd-take-18,000-years-at-Helios'-top-speed dept.

Astronomers have reportedly discovered an Earth-like exoplanet in the habitable zone of Proxima Centauri, one of the closest stars to our Sun. However, the claim is based on an anonymous source who is said to have leaked the news ahead of an announcement by the European Southern Observatory:

[In] what may prove to be the most exciting find to date, the German weekly Der Spiegel [translation] announced recently that astronomers have discovered an Earth-like planet orbiting Proxima Centauri, just 4.25 light-years away. Yes, in what is an apparent trifecta, this newly-discovered exoplanet is Earth-like, orbits within it's sun's habitable zone, and is within our reach. But is this too good to be true? [...] Citing anonymous sources, the magazine stated:

The still nameless planet is believed to be Earth-like and orbits at a distance to Proxima Centauri that could allow it to have liquid water on its surface — an important requirement for the emergence of life. Never before have scientists discovered a second Earth that is so close by.

In addition, they claim that the discovery was made by the European Southern Observatory (ESO) using the La Silla Observatory's reflecting telescope. Coincidentally, it was this same observatory that announced the discovery of Alpha Centauri Bb back in 2012, which was also declared to be "the closest exoplanet to Earth". Unfortunately, subsequent analysis cast doubt on its existence, claiming it was a spurious artifact of the data analysis.

However, according to Der Spiegel's unnamed source – whom they claim was involved with the La Silla team that made the find – this latest discovery is the real deal, and was the result of intensive work. "Finding small celestial bodies is a lot of hard work," the source was quoted as saying. "We were moving at the technically feasible limit of measurement." The article goes on to state that the European Southern Observatory (ESO) will be announcing the finding at the end of August. But according to numerous sources, in response to a request for comment by AFP, ESO spokesman Richard Hook refused to confirm or deny the discovery of an exoplanet around Proxima Centauri.

[Continues...]

Here's an article we ran about the possible discovery of Alpha Centauri Bb.

There is some debate about the habitability of red dwarf systems in general. Nevertheless, one of the minds behind Breakthrough Initiatives/Project Starshot is enthused about the possible discovery. It seems likely that at the very least, almost all stars have planets or dwarf planets orbiting them.

Proxima Centauri will move closer to the Earth over the next 26,700 years at a rate of 22.4 km/s, until its closest approach of 3.11 light years.


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  • (Score: 5, Informative) by takyon on Thursday August 18 2016, @01:46PM

    by takyon (881) <reversethis-{gro ... s} {ta} {noykat}> on Thursday August 18 2016, @01:46PM (#389581) Journal

    The closer it is to Mercury's size, the harder it would be to detect. So there will be a bias towards things at least the size of Earth.

    As for super-Earths, it's possible that they are more conducive to life than the smallest of planets:

    http://www.universetoday.com/108964/super-earths-could-be-more-superhabitable-than-planets-like-ours/ [universetoday.com]

    Bigger rocky planets would have a host of advantages, argue McMaster University’s Rene Heller and Weber State University’s John Armstrong in a paper recently published in Astrobiology. Among them: These worlds would have tectonic activity that takes longer to happen, meaning that the conditions would be more stable for life. Also, a bigger mass implies it’s easier to hang on to a thick atmosphere and to have “enhanced magnetic shielding” to hold a planet’s own against solar flares.

    https://en.wikipedia.org/wiki/Super-Earth#Habitability [wikipedia.org]

    According to one theory,[84] super-Earths of about two Earth masses may in fact be more conducive to life than our own planet. The higher surface gravity would lead to a thicker atmosphere, increased surface erosion and hence a flatter topography. The end result could be an "archipelago planet" of shallow oceans dotted with island chains ideally suited for biodiversity. A more massive planet of two Earth masses would also retain more heat within its interior from its initial formation much longer, sustaining plate tectonics (which is vital for regulating the carbon cycle and hence the climate) for longer. The thicker atmosphere and stronger magnetic field would also shield life on the surface against harmful cosmic rays.[85]

    Things could get dicey as we move past 2-3 Earth masses to the realm of 5-10 Earth masses, but at least surface gravity shouldn't be increasing linearly with the increase in mass. For example, a ~7 Earth mass planet [centauri-dreams.org] might have a surface gravity of less than 2g.

    Finally, having an exoplanet in the habitable zone gives you another chance at life: exomoons. Having an exomoon around your exoplanet could bypass some of the effects of having the exoplanet tidally locked with the star. I guess the problem here might be the small size typical of most moons. But bodies like Titan give us hope that even smaller-than-Earth satellites can have thick atmospheres. Titan itself may become habitable [wikipedia.org] in the future.

    Our solar system's largest satellites [wikipedia.org] orbit the gas giants, with two exceptions being Earth's Moon and Pluto's Charon. In the future, we'll have a better understanding of the lower limits required for a satellite to have a thick atmosphere, and the upper limits of satellite size around smaller exoplanets. But if Proxima Centauri's possibly existing habitable exoplanet is closer in size to a mini-Neptune, that might mean it has more satellites, larger satellites, and a better chance to have satellites with thick atmospheres.

    We might get another chance to find interesting satellites in our own solar system, if "Planet Nine" [wikipedia.org] can be found and it is a mini-Neptune. Heck, even P9 and its satellites could support microbes in a subsurface ocean. Hopefully we will be able to image it with the James Webb Space Telescope.

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