
A low-mass planet candidate orbiting Proxima Centauri - pinewurst
https://advances.sciencemag.org/content/6/3/eaax7467
======
JimboOmega
1.5 AU from Proxima (so 50% farther than earth is from the sun), which is
itself much less luminous than the sun? I'd imagine it's a very, very cold
planet and receives many times less light than earth does.

Neat to find a planet, but it doesn't sound like one humans would want to have
much to do with.

~~~
hazeii
Plus at 5.8 times (+-1.9) Earth's mass it's only low mass compared to most
extrasolar planets.

Still, there may be life that's happy with slow and heavy.

~~~
jbotz
Keep in mind that surface gravity depends very much on density. The earth is
pretty dense, having a core of mostly iron. Even a rocky planet can be a lot
less dense if it's iron-poor, and so could have a reasonable surface gravity
(by our standards) even if several times the earth's mass.

~~~
bmgxyz
Indeed. I learned this the hard way when I made some claim to a political
science roommate about the local acceleration due to gravity near one of the
outer planets and was corrected and embarrassed. It's easy to forget that
gravitation is the result of many tiny things all pulling on each other, not
just a few big and small things.

I looked through the paper and didn't see anything about the radius of the
planet candidate. I suppose it's quite difficult to determine it from so far
away. Is a value known? If so, that would obviously give a good idea about the
local _g_.

~~~
Robotbeat
The radius is often not known. Radius is found most easily with transiting
exoplanets, which are easy to detect but also only visible if you're lined up
along the plane of the exoplanet's orbit.

You can also possibly find it via imaging, but even then, since you can't
directly resolve it better than a point light source, you're making
assumptions about albedo that lead to a wide dispersion in possible radii.
High resolution optical imaging would require a telescope roughly 1-2km in
diameter. Pretty tough... and because of the glare of the star, would be
nearly impossible to image with an interferometric (i.e. non-filled-aperture)
telescope since the light gather power would be so low. However, astronomers
are incredibly clever at pulling data out of tiny points of light, so there
may be some way.

~~~
bmgxyz
Thanks for this, it's quite interesting.

I have a friend who used to work in a lab doing super-resolution microscopy
(i.e. beating the diffraction limit by various means) for use with bio/medical
applications. Some of the techniques he told me about have to do with more or
less taking lots of data from many images and assembling it all into something
meaningful. I suppose what you're describing as "pulling data out of tiny
points of light" is kind of the same thing. It's just that the scale is
different.

------
nafey
The Trisolaran home world

------
unlit_spark
I get excited every time I hear about a possible habitable planet, but after
10 seconds I remember that this means nothing and will mean nothing for a few
centuries as we won't be able to reach any other planet that's billions of
kilometers away.

~~~
lazyjones
Some sort of cryogenic hibernation for space travel is not unrealistic within
the next few decades.

[https://www.airspacemag.com/space/hibernation-for-space-
voya...](https://www.airspacemag.com/space/hibernation-for-space-
voyages-180962394/)

~~~
Cthulhu_
Even with that I hope we get to see missions where they send unmanned craft in
that direction in my lifetime. I mean it's still only Voyager and New Horizons
(afaik) that have been sent on a trajectory out of our own solar system on
purpose. (faux edit: looking up the wiki page, it's the 5th to escape the
solar system).

An unmanned mission would probably have to go even faster, and probably has to
be a bigger craft with better on-board power supply (with backups) and a big
communications array. Maybe it would even need similar craft following it
after a while to form a chain of communications relays on their way out.

~~~
mkl
Nitpick: 5th to reach solar escape velocity. New Horizons, Pioneer 10, and
Pioneer 11 have not passed the heliopause yet, which is usually considered the
"boundary" of the solar system.

------
Apocryphon
Sid Meier's Proxima Centauri

~~~
deepaksurti
Related HN discussion I guess [1]

[1]
[https://news.ycombinator.com/item?id=21901268](https://news.ycombinator.com/item?id=21901268)

