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Stop Press! Possible Earth-Sized Planet Orbiting Nearest Star.


bornagainathiest

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Enjoy!

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The Bad Astronomer doesn't rule out 100 % that the planet might even be Earth-like... of course possibility doesn't mean reality :scratch:

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Well, that is fascinating!

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I guess you could say it's earth-like... for certain definitions of earth-like.

 

But a planet that's at least 1.3 earth masses and (probably) tidally locked around a red dwarf (which, if I'm not mistaken, puts out more heat than visible light, and even that's much more in the red part of the spectrum) sounds pretty unlike earth to me.

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In the sense that similar life forms could have emerged I guess

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Folks, please remember that Proxima Centauri b is Earth-sized.

 

That's important for the following reasons.

 

1.  

If your 'scopes can't detect anything as small as the Earth, then there's no point in looking for Earth-like planets.  You simply won't find them.  You first have to have the ability to find Earth-sized planets before you can determine if they are Earth-like or not.

 

2.

The Kepler probe has found 1,000's of planets and a clear pattern emerges from the data.  Stars are almost never orbited by just one planet.  The stats indicate that if you've found one planet orbiting a star, it's almost certain to be one of several.  So, Prox b is overwhelmingly likely to one of a system of planets.  The fact that such a small planet was the first to be discovered suggests that some of the others will also be small.  The logic behind this is that a larger planet creates a larger signal, which would show up first in the data.  Since such a large planet hasn't been detected, we can tentatively conclude three things.  

 

First, there are no large planets anywhere near Prox b's orbit in that star's habitable zone.  This is good news.  It leaves room for other small planets to orbit in or near the hab zone.

 

Second, if there is a large planet in this system, it must orbit sufficiently far out not to have a significant effect on the data acquired so far.  In a nutshell, since Mercury's orbit takes 88 days, you'd only have to observe for 264 days to see it go round the Sun three times.  So if you'd watched for 365 days you'd see three spikes in the data - a clear indicator of a planet in a regular orbit.  But since Jupiter takes 12 years to complete one orbit, you'd have to wait the best part of five decades to see three similar data spikes.  Therefore, a giant planet could be orbiting Prox b, but we need a lot more data, taken over a longer period to detect it.

 

Lastly, if there is a giant planet further out than Prox b, this could also be a good thing.  According to some models of our solar system's gravitational dynamics, the strong gravity of Jupiter 'sweeps up' rogue comets and asteroids before they can enter the inner orbits of the smaller planets like Mars, the Earth, Venus and Mercury.  If that's so here, then it could also be the case around Proxima Centauri.  A giant planet in a Jupiter-like orbit might keep small fry like Prox b safe from devastating asteroid and comet impacts.  Or at least, somewhat safer. 

 

 

3.

Small planets orbiting close to their stars cannot be gas giants like Jupiter, Saturn, Uranus and Neptune.  Their atmospheres would be vaporized by the heat of their host star.  Nor can they be icy worlds like Pluto or the icy moons Titan, Europa, Ganymede or Callisto.  The icy crusts and mantles of such worlds would first melt and then vaporize in such close proximity to the star.  This process of elimination leads us to conclude that an Earth-sized planets like Prox b, orbiting where it is - must be composed of rock and metals, like the four inner planets of our solar system.

 

Thanks,

 

BAA.

 

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  • 2 weeks later...

More on Proxima b.

 

http://phl.upr.edu/press-releases/proxb

 

Enjoy!

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