Closest Not-Really-Earthlike Earthlike Planet Found Sort of!

[JasonPratt]

 ::)

So the interwebs are atwitter this weekend and past week, with the discovery of what (due to its orbital characteristics) is most likely a rocky planet orbiting close around Proxima Centauri, our nearest known solar system. (Discovered or maybe distance-located after Alpha Centauri, due to the star's relative dimness and size, which will be a factor soon.)

Instead of announcing that a Mercury-like planet has been (probably) detected in the Proxima system, well shoot that don't market well. So IT'S THE CLOSEST EARTHLIKE PLANET TO US EVAR GUYZ!

Of course the problem is that it's ludicrously close to its star, but the star is relatively weak enough that it might not be cooking the surface like on Mercury so liquid water could, in theory, exist in small amounts. Somewhere.

But unless its rotational/orbital characteristics are completely different from anything else we've discovered or astrocalc'd up theoretically, it either has no day-night cycle at all, or a weird day-night cycle like Mercury (two cycles every three orbits around the star, with an 11 day orbit for Proxima b) -- so, very different in fact from Earth.

Really, it's only similarity to Earth is that it's probably a rocky planet about 1/3 our mass: gas planets are usually the close ones in, our solar system being a rare exception (the new mechanics not being at all well understood for why we'd have so many gas planets so far out and so many rocky planets so close), but at that distance even Proxima's relatively weak gravity pull would likely rip a gas planet apart quickly, especially one so much less massive than us (if such a gas planet could even exist -- I've honestly never heard). So it's probably rocky, in a broad temperature range that doesn't in itself immediately exclude liquid water, and that's the total limit of how Earthlike this planet is. Ah well.

[Pete Dero]

http://www.skyandtelescope.com/astronomy-news/exoplanet-found-around-proxima-centauri-2408201623/

Astronomers have discovered a planet in the habitable zone of the closest star to the Sun.

Whether Proxima Cen b actually is habitable remains a wide-open question. Technically it lies at the right distance from its star that, if it has the right composition and atmosphere, it would be the right temperature to sustain liquid water on its surface.


No mention of Earthlike in this scientific article.


By the way : Alpha and Proxima Centauri are both stars of the same system.
It is actually a triple-star system (bound together by gravity). Alpha Centauri A and B are two bright, closely orbiting stars with a distant, dim companion, Proxima Centauri. The inner binary appears to the unaided eye as a single star, the third brightest in the night sky, but it lies 4.37 light years from the Sun. Proxima Centauri alone claims the honor of being our true nearest stellar neighbor at only 4.24 light years away.

[mirth]

I think we all know who lives there

[bbmike]

If our universe is anything like a 4x game pirate ships are already on the way to Earth.

[mirth]

If our universe is anything like a 4x game pirate ships are already on the way to Earth.

If they can keep Hillary out of the White House, I welcome our new alien overlords.

[JasonPratt]

I think we all know who lives there

...restraining.... geek.... commmeennnntttttt.....!

If our universe is anything like a 4x game pirate ships are already on the way to Earth.

Yep, on reading the news (even after cynically fact-checking it ;) ), I immediately wanted to fire up a game of Sword of the Stars or Distant Worlds: Universe! sigh. 

[mirth]

I think we all know who lives there

...restraining.... geek.... commmeennnntttttt.....!

Dammit!  You saw through my attempt to get you to expound on how the Centauri aren't from the Alpha Centauri system :P

[JasonPratt]

I had it typed up. I could only resist so far. It felt therapeutic.  :))

You will notice I also refused to expound on the difference between Proxima and Alpha, although being quite the baroque operator I just mentioned it anyway...  :P

[mirth]

You will notice I also refused to expound on the difference between Proxima and Alpha, although being quite the baroque operator I just mentioned it anyway...  :P

Well played, sir. Well played.

[Nefaro]

Really, it's only similarity to Earth is that it's probably a rocky planet about 1/3 our mass: gas planets are usually the close ones in, our solar system being a rare exception (the new mechanics not being at all well understood for why we'd have so many gas planets so far out and so many rocky planets so close), but .....
<snip>

Keep in mind the reason for the large majority of discovered exoplanets being huge gas giants, many of which orbit closely around their star - the methods being used to find them.

They're measured either by dips in light output when a planet crosses in front of the star (the Transit Method), or by the gravitational wobble an exoplanet has on the parent star while circling it.

Both methods generally only find very large/massive planets, in relation to the parent star, due to those detection methods.  However, they don't need to be as quite as massive when they're in close orbits.


Simply put, these two main methods, which have been the source for nearly all exoplanet detections, is heavily skewed towards finding large gas giants, planets in very close orbit, and especially a combination of the two.  Rocky planets aren't detected as often because many wouldn't have enough mass, or orbit close enough, to be found yet.

The overall picture is still very incomplete regarding exoplanetary system make-up.  We just don't have the capability to detect every possible planet around any other star.

[BanzaiCat]

The "Breakthrough Starshot" project might...MAYBE...allow us to visit other stars within our lifetime. If it's not utter BS. And we live a long, long, long time.

Long story short, it's a proof-of-concept project where they hope to build unmanned probes that can travel at upwards of 20% of the speed of light, getting them to Proxima Centauri within 20-30 years or so. I think they were saying that they might possibly be able to launch the first probe by 2036.

So if they keep to their timetable (hahahahaha), it'll be 2056 to 2066 or so before our Earth probes reach Proxima Centauri. I don't hold out hope that I won't be senile by then, if I'm even alive still.

[Pete Dero]

And add another 4.5 years for any signal to get back to us ...

[MikeGER]

even faster way to check exoplanets for atmosphere composition ....and a nice picture for the media also in the package
a occulter floating in space block the central star and a space telescope (that could be a dedicated or the planed replacement for Hubble which will get launched 8/2018 anyway) capturing the dim exoplanets radiation....   and its only $750Mio for the starshade occulter
 
https://en.wikipedia.org/wiki/New_Worlds_Mission

[BanzaiCat]

And add another 4.5 years for any signal to get back to us ...

Meant to mention that.  O0

[JasonPratt]

Keep in mind the reason for the large majority of discovered exoplanets being huge gas giants, many of which orbit closely around their star - the methods being used to find them.

True, although I think there are also theories for why gas giants ought to be closer and rockies farther out.

But you're also right, the current detection technology skews a particular direction.