
A Second Planet May Orbit Earth's Nearest Neighboring Star - headalgorithm
https://www.scientificamerican.com/article/a-second-planet-may-orbit-earths-nearest-neighboring-star/
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jcims
From my stubby pencil work it seems that the apparent diameter of this planet
would be within an order of magnitude of the black hole image from earlier
this week (~120 vs 40 micro arcseconds), which is 3+ orders of magnitude
smaller than the resolving power of even our largest optical telescopes. I
have a feeling ill never see an image of another planet in this life. :(

~~~
hansjorg
[https://en.m.wikipedia.org/wiki/List_of_directly_imaged_exop...](https://en.m.wikipedia.org/wiki/List_of_directly_imaged_exoplanets)

[https://en.m.wikipedia.org/wiki/Methods_of_detecting_exoplan...](https://en.m.wikipedia.org/wiki/Methods_of_detecting_exoplanets#Direct_imaging)

~~~
jcims
I guess what I'm hoping for is something akin to Hubble's photo of Pluto. A
blurry blob with patches of color.

In the animated image at the top right of the page you linked, those planets
are between 14 and 69 AU from their star. Let's pick the one at about 5
o'clock, it's the second most distant at about 25AU, or ~2.5 billion miles
from the little yellow star.

Wikipedia says its ~1.3 times the radius of Jupiter, so let's round up to get
even numbers and say it's 125,000 miles in diameter. That means the actual
scale size of that planet is 1/20,000th the distance between those two dots in
the image, meaning that blurry dot is about 2,000 times as large as the planet
itself. We have a long way to go.

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acqq
> Midway in mass and size between Earth and giant worlds like Neptune, such
> worlds may either be mostly gassy worlds offering slim chances for life as
> we know it, or instead super-sized versions of our own habitable, rocky
> world.

However:

> Astronomers say they may have detected a second planet ... with a minimum
> mass roughly six times that of our planet’s.

If it's a planet 6 times more massive than Earth, it's a gaseous planet, and
nothing like Earth:

[https://www.forbes.com/sites/startswithabang/2016/11/08/is-e...](https://www.forbes.com/sites/startswithabang/2016/11/08/is-
earth-our-solar-systems-missing-super-earth/)

So don't expect that humans will ever land on that, even if they reach it once
(for it rotating around the nearest star).

Apparently "super-sized versions of our own habitable, rocky world" can be
just slightly bigger than Earth.

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gassyEarth
Doesn't 6 times the mass get ~6 times the gravity, if we're talking about a
rocky planet of comparable density?

If I weigh 600 Kg on a super-sized version of earth, it doesn't matter what
amount of water or atmosphere is present. It's not habitable, even if it's a
temperate 30 degrees celsius, with refreshing sun showers and a briney
primordial soup.

~~~
acqq
"6 times the mass get ~6 times the gravity, if we're talking about a rocky
planet of comparable density?"

There's no such thing, apparently, see the link I've already posted. According
to the latest research, six times the Earth mass the planet is gaseous
(Neptune-like). The limit over which the planet is Neptune-like is just two
times Earth mass, which corresponds to just a little bigger radius than
Earth's:

"a world that's 2.0 Earth masses and rocky will only be about 25% larger in
radius than Earth; larger than that and you're probably Neptune-like, with a
massive hydrogen/helium envelope."

[https://www.universetoday.com/22070/surface-of-
neptune/](https://www.universetoday.com/22070/surface-of-neptune/)

"In short, there is simply no way one could stand on the “surface of Neptune”,
let alone walk around on it."

