Among the abundance of recently discover planets around other stars , one identifiable group has puzzled astronomers . Ranging between two and four times the Earth ’s wheel spoke , the object have spurred disputation on whether they are low flatulence giants – Neptune ’s smaller cousins – or if they are primarily made of weewee . The possibility these are stony worlds like our own has already been for the most part dismissed .
Whether spirit could thrive in oceans thousands of klick inscrutable is a corking unknown , but it certainly seems more likely than on a universe of gas . novel research favors the pee world hypothesis , meaning that if life can exist under such term , the universe may be fill with it .
Before we set forth find planets beyond our Solar System , our expectations were shaped by what we could see . Many stargazer expected a premix of jumpy worlds the sizing of Earth or modest as well as much large flatulency giants . Others predicted a smooth curved shape , with larger size increasingly rare . Instead , we have find an abundance of planets alike in size of it to Earth and a 2nd family that have a radius between two and four time big . There ’s an challenging disruption at 1.8 - 2.0 Earth wheel spoke . Harvard University’sDr Li Zenghas identified major planet above this disruption as in all likelihood made mostly of water , whether in liquid or hearty configuration .
Most of the planets in dubiousness were measured through the drop-off in light collect by the Kepler space telescope as they pass on across their star ’s brass . This tells us their sizing but not mass . However , in some cases we have been able to conduct play along - up measurements with the Gaia space scope to honor the wobble the maternal star undergoes in response to the major planet ’s arena , thus uncover their mass .
The most common size for the worlds Kepler found is 2.5 Earth radius , Zeng report inProceedings of the National Academy of Sciences . That makes for a volume 16 times that of the Earth . Those whose deal could be measure clump between 6 and 15 Earth Mass , only a little less dim than Earth ( Neptune , being mostly gas , is less than a third as dense as Earth ) . The determination is consistent with at least a quarter of the planet being water or ice around a metallic and rocky core . Any atmospheres are probably thin veneers around the planet , similar to our own .
Many of these planets exist in their star ’s inhabitable geographical zone , where body of water can exist in fluid form , so they are candidate for life . In modeling how these major planet formed , Zeng get through conclusions relevant closer to home . He explains Uranus and Neptune as mergers of smaller arctic cores that prevent the build - up of hydrogen and He Jupiter experience .
