I would like to learn a little bit more about the interesting cosmic structures and planets out there. I already know about these planets and cosmic structures:

Gliese 436 b - Planet made of superheated ice

55 Cancri e - Planet made of Diamond

Huge LQG - Second largest cosmic structure, stretching 4 billion light-years across and containing 73 quasars

Hercules-Corona Borealis Great Wall - Largest cosmic structure, border between the Hercules and Corona Borealis constellations stretching 10 billion light-years across

Kepler 186f - Planet that is quite similar to earth, having a very high chance of being habitable by other lifeforms

The Giant Void - A large void that is 1.3 billion light years across

Sagittarius A - Supermassive black hole in the center of the milky way galaxy. It has a mass of about (4.31 ⁺ 0.38) x 10⁶.

I do know more, but they are not coming to my mind, and I would like to learn a little bit more about this, as it is quite interesting. Also, other people who want to learn more can do so by looking at this discussion.

The composition of extrasolar planets is unknown very accurately. A handful of teams claim to have observed atmospheres and even a composition, but this relies on a few received photons, and to my knowledge, has not been observed by two independent teams. So while we may have this knowledge in the future, presently it's more hype and buzz for popular science and the general press.

The composition of extrasolar planets is unknown very accurately. A handful of teams claim to have observed atmospheres and even a composition, but this relies on a few received photons, and to my knowledge, has not been observed by two independent teams. So while we may have this knowledge in the future, presently it's more hype and buzz for popular science and the general press.

 

This really doesn't answer my question