An exoplanetary system about 116 light-years from Earth could flip the script on how planets form, according to researchers who discovered it using telescopes from NASA and the European Space Agency, or ESA.Four planets orbit LHS 1903 — a red dwarf star, the most common type of star in the universe — and are arranged in a peculiar sequence. The innermost planet is rocky, while the next two are gaseous, and then, unexpectedly, the outermost planet is also rocky.This arrangement contradicts a pattern commonly seen across the galaxy and in our own solar system, where the rocky planets (Mercury, Venus, Earth and Mars) orbit closer to the sun and the gaseous ones (Jupiter, Saturn, Uranus and Neptune) are farther away.AdvertisementAdvertisementAstronomers suspect this common pattern arises because planets form within a disk of gas and dust around a young star, where temperatures are much higher close to the celestial body. In these inner regions, volatile compounds such as water and carbon dioxide are vaporized while only materials that can withstand extreme heat — such as iron and rock-forming minerals — can clump together into solid grains. The planets that form there are therefore primarily rocky.In our solar system, the rocky planets are closer to the sun, followed by the gas giants. – NASA/Lunar and Planetary InstituteFarther from the star, beyond what scientists call the “snow line,” temperatures are low enough for water and other compounds to condense into solid ice — a process that allows planetary cores to grow quickly. Once a forming planet reaches about 10 times the mass of Earth, its gravity is strong enough to pull in vast amounts of hydrogen and helium, and in some cases, this runaway growth produces a giant gas planet such as Jupiter or Saturn.“The paradigm of planet formation is that we have rocky inner planets very …
