The planets in our solar system each have their own personality, with different sizes, temperatures and compositions. There are the icy worlds and the gassy ones, the scorching and the frigid. The same rule can be applied to the universe as a whole -- it's full of enormous, amazing things, like supermassive black holes and stars that rotate hundreds of times a second, but the planets offer their own flavors to the vast melting pot of existence.
Not all gas giants are created equal. Observations of the Neptune-like exoplanet HAT-P-26b show that its atmosphere is less rich in heavy elements than expected, meaning it probably formed close to its star. In our solar system, the gas giants' metal content can be plotted on a straight line: the lighter a gassy planet is, the more heavy elements its atmosphere contains. Jupiter's atmosphere has less heavy elements than Neptune's, for example. But in order to study the atmospheres of planets around other stars, they need to meet very particular conditions: the planet must pass between its star and us, and the star must be bright enough for us to discern changes in its light as it shines through the planet's atmosphere.
Since the rings of Saturn were first spotted in the 17th century, studying the feature has moved from earth-based telescopes to spacecraft such as Voyager and Cassini. However, the origin of the rings remained unclear. Now, scientists also have computers to simulate what the solar system looked like eons ago. Some four billion years ago, as the solar system was forming, objects about one-fifth the size of Earth wandered near the giant planets (Jupiter, Saturn, Uranus and Neptune). This period of time is known as the "Late Heavy Bombardment" by astronomers.
For the first time, astronomers captured a clear image of a young planet forming around a star. It was captured by the European Southern Observatory's Very Large Telescope (VLT) in the Atacama Desert in northern Chile. You can see the young planet, named PDS 70b, as a bright ball to the right of the center of the photograph above. It's carving a path through what is known as a protoplanetary disc, the huge collection of gas and dust that surrounds younger stars. "These discs around young stars are the birthplaces of planets, but so far only a handful of observations have detected hints of baby planets in them," Miriam Keppler, an astronomer at the Max Planck Institute of Astronomy (MPIA), which led the study, said in a statement.
Scientists have found a lot of planets in other solar systems that have a rocky makeup like Earth and are roughly the same size, but that doesn't mean they are Earth-like planets. Astronomers are saying that these rocky exoplanets might just be the scorched dead bodies of huge gassy ones that had their atmospheres ripped away from them, leaving behind their solid but uninhabitable cores. A new study suggests that all these rocky exoplanets orbiting close to their stars may have originated as gas giants -- planets that are comparable to our own Jupiter and Saturn -- but the radiation gushing outward from their nearby stars blew away all the gas like it was the seeds of a dandelion. The idea could have implications for how scientists look at planetary formation as well as the search for habitable worlds and extraterrestrial life. In recent years, telescopes have detected a large number of alien planets and many of them, including in our very own Milky Way galaxy, are rocky orbs.