

Robotic telescope discovers three super-earth planetary neighbors - anigbrowl
http://newscenter.berkeley.edu/2015/04/28/robotic-telescope-discovers-three-super-earth-planetary-neighbors/

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kbenson
Is super-earth some term with meaning here, or are they purely using it as a
headline? I don't imagine with orbits closer to their host start than mercury
and mass 7-8 times that of the earth that they are actually all that earth-
like.

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antognini
It's a term used to describe a planet more massive than the Earth, but less
massive than Neptune. These planets are thought to be typically rocky. From
the introduction of the paper:

> The archetypical planets of our Solar System --- Jupiter the gas giant,
> Neptune the "ice" giant, and Earth the terrestrial planet --- represent an
> incomplete inventory of the planet types in our galaxy. We are locally
> impoverished in "super-Earths," the broad category of planets intermediate
> in size and mass between Earth and Neptune.

~~~
logfromblammo
Solar inner planets are mostly metal-silicate worlds. The seven major
satellites are mostly hydric.

Under different circumstances, particularly if there were no Jupiter, we might
expect a metal-poor, water-rich rocky planet in the system, larger in volume
and more massive than Earth.

Jupiter has had a huge influence on the solar system, and if that mass were
not concentrated there, it would have to be _somewhere_. The H and He would
probably have blown away, but the silicaceous, carbonaceous, hydric, and
metallic materials might have contributed to terrestrial planets.

If you squashed all the moons of Jupiter together along with the entire
asteroid belt, you almost get a wetter, less dense Mars. Add the 5% of Jupiter
that isn't light gases, and you get about 1*10^26 kg, which is about 16 times
the mass of Earth.

So if the light gases blew away instead of forming Jupiter, and the remaining
mass formed asteroids that combined via capture and collision, the solar
system could have had a super-Earth. But instead, Jupiter sucked down most of
that mass and put the rest into stable orbits around itself.

