55 Cancri e

A thick atmosphere has been detected around the rocky planet 55 Cancri e.

About 55 Cancri e:

• Formally named Janssen, it is an exoplanet orbiting a Sun-like host star, 55 Cancri A.
• It was discovered in August 2004, making it the first super-Earth discovered around a main sequence star, predating Gliese 876 d by a year.
• Its mass is about eight Earth masses and its diameter is about twice that of the Earth.
• It is the innermost planet in its planetary system, taking less than 18 hours to complete an orbit.

About Rocky Planets:

• Rocky planets, also known as terrestrial planets, are those made up mostly of solid rocks or metals.
• Their compositions include silicate rocks and metals, with a dense metallic core.
• Unlike gas giants, rocky planets have solid, well-defined surfaces.
• They tend to be smaller and denser than gas giants.
• Their atmospheres are usually thinner, and they can range from having no atmosphere at all, like Mercury, to having a robust atmosphere with weather systems, like Earth.