Gemini Planet Imager looking for clues on the growth of gas giants
The Kepler Space Telescope is very good at its job, having lead to the discovery of over 500 exoplanets, including possible proxies for Earth. Kepler finds these planets by looking for their shadows as they pass in front of stars, but this isn’t our only way to detect distant worlds. The Gemini Planet Imager (GPI) takes a different approach, and looks for the light created by the planets themselves.
Looking at our own solar system, you wouldn’t assume planets were giving off much light on their own. Sure, auroras and artificial light sources can be seen in space, but only from very close differences. The light the GPI can pick up is much more intense, and is detectable across deep space thanks to some planets’ super-heated atmospheres. The most recent example of this is 51 Eridani b, which has a methane-based atmosphere, burning at 800° F.
Jupiter’s baby pictures
Obviously, we’re not looking a roasting hot gas giant like this as a future destination for human exploration. 51 Eridani b is valuable because it may help flesh out the story of how gas giants are formed. The exoplanet’s makeup closely resembles Jupiter, but since it’s only 20 million years old instead of 4.5 billion years old, it may provide insight into the early life of such a planet. Currently there are two models about how gas giants are created, either rapidly leading to more heat or slowly, leading to a cooler, more solid planet. Even if the answer proves to be a little of both, ‘witnessing’ the growth of young gas giants will help fill in these gaps.
Once we have a better idea of how gas giants are formed, we should have more to go on when looking for more elusive planets, like relatively cool, solid stand-ins for Earth. For now, gaseous planets are the easier target for the GPI, with the glowing 51 Eridani b marking a strong first milestone.
My first grader asked: What’s at the middle of a gas giant like Jupiter? Can you go all the way through it? The exact composition of Jupiter’s core is still unknown. One hypothesis is that it has a soupy core of liquid metallic hydrogen with another layer of hydrogen on top of that. The other leading theory puts a giant rock there, at least 14 times the size of Earth. Either way, nobody is moving though the middle of the planet.
Source: Baby Jupiter Discovery a Step Toward Rewriting Planet Formation Models by Calla Cofield, Space.com