A thick atmosphere has been identified around a planet about twice as big as Earth that sits outside our solar system, according to newly released research.
The discovery was reported in the journal Nature on Wednesday.
Known as 55 Cancri e or Janssen, the so-called 'super-Earth' is one of the few rocky exoplanets outside our solar system with a significant atmosphere, surrounded by carbon dioxide and carbon monoxide. Earth's atmosphere is comprised of gases such as nitrogen, oxygen and argon.
The research presents "the firmest evidence yet" that the planet has an atmosphere, Ian Crossfield, an astronomer at the University of Kansas who studies exoplanets, told the Associated Press.
According to NASA, super-Earths are a class of planets unlike any in our solar system. They are larger than Earth yet smaller and lighter than the likes of Neptune and Uranus, and can be made of gas, rock or a combination of both. They are between twice the size of Earth and up to 10 times its mass.
Super-Earth is a reference only to an exoplanet's size, but does not suggest they are necessarily like our home Earth. The true nature of these planets remains uncertain as we have nothing like them in our own solar system.
As per NASA, 55 Cancri e is "relatively close" to Earth at a distance of 41 light-years (one light-year is nearly 9.7 trillion kilometres). It orbits very close to its star, Copernicus, rotating around it every 18 hours. Due to this proximity, it's tidally locked by gravity just as the Moon is to Earth. This means one side of 55 Cancri e, referred to as the 'day side', is always under the heat of its star; alternatively, the 'night side' remains in the dark and is much cooler. The temperature difference is dramatic: the hottest side is nearly 2426C, and the coolest is 1126C.
The surface of the exoplanet is covered with magma oceans, the research noted, the gases from which may play an important role in holding its atmosphere steady. The molten surface is completely uninhabitable.
Scientists say the discovery indicates other such planets with thick atmospheres could exist - some of which may be more hospitable than 55 Cancri e.
Scientists believe exploring the super-Earth may lead to greater understanding of how Earth and Mars might have evolved.
