Closest Habitable Planet to Earth Found | Pale Red Dot’s Proxima b | What the Physics


Today a pretty awesome discovery has
been announced by the team behind Pale Red Dot. They’ve found a potentially
habitable earth-like exoplanet orbiting around the nearest star to the Sun,
Proxima Centauri only 4.24 light-years away. Now you might remember Pale Red Dot back
from my video in March about the hunt for exoplanets around red dwarf stars,
worlds which may be very similar Superman’s home planet of Krypton. I encourage you
to watch the full video for all the details, but TLDW, Pale Red Dot was a campaign
taking radial velocity measurements of Proxima Centauri each night for around
three months at the beginning of 2016. They were looking for wobbles in
that star’s motion to indicate the presence of a planet, a planet that might
have been hinted at before but we weren’t able to properly pin down
because of the star’s variability. Here you can see the actual measurements they
took and our best fit to the data. What’s great is that you can clearly see
oscillations in the star’s relative velocity to us, the tell-tale sign of a
planet now dubbed Proxima b. So what’s this planet like? Well from our fit to
the data we can work out a lot of the properties of Proxima b. Firstly its
year, the amount of time it takes to do a full orbit around its star, is incredibly
short just 11.2 days. That means the planet is incredibly close to the star,
just five percent of the distance between the Sun and the Earth, or about a
tenth of that to mercury. But red dwarf stars are a lot smaller and cooler than
main-sequence G-type stars like our Sun. In fact Proxima b would only be
receiving sixty-five percent of the stellar radiation that we get here on
earth, placing it firmly within the habitable zone: the region where we think liquid water might be able to form on
the surface. Now there are some caveats to that, if Proxima b has no atmosphere
it would be a rather chilly minus 39 degrees C, but the same calculation
applied to the Earth puts us at only a few degrees warmer. In our case it’s the
presence of greenhouse gases which makes it suitably warm for liquid water, and
therefore life as we know it, to form. The same could be true of Proxima b, it’s just we don’t know yet.
What about the size of the planet? The radial velocity method can give a direct
estimate of mass but because of potential orientational effects, it’s
just a lower bound known as the minimum mass.For Proxima b this is 1.3 times
that of the Earth. Now unlike the transit method, we can’t
measure the physical size of the planet but using the minimum mass and assuming
it has a similar density to Earth then it’d only be ten percent bigger with ten
percent stronger gravity on the surface. And from that surface, the red dwarf star
would appear three times bigger in the sky than our Sun from Earth this could
make for a pretty stunning view if we ever get there. With current technology
and some clever slingshot maneuvers it would take at least 15,000 years to
reach Proxima Centauri. On the other hand the ambitious Starshot project wants to
send tiny robots propelled by powerful earth-based lasers taking only 20 years. This really is just the first step into
finding out what the closest exoplanet to us is really like and only by looking
more closely with different scientific instruments and upcoming ones as well
can we start to answer all of these questions that are just beginning to
crop up, including the big one: is there anyone out there? It’s an exciting time
to venture into the unknown. thank you so much for watching this
video I hope you enjoyed it if you did you can give it a like you can also
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well thank you very much

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