AstroTalk Episode March 30, 2017

A Lost Planet the Size of Neptune and Exoplanets Kepler A B C D E, and a Caldera on the Moon

3:11pm - 3:26pm

Astronomers at Yale have discovered a lost planet about the size of Neptune, in a solar system 3,000 light-years from Earth. Kepler-150 was overlooked for several years, probably because of its long orbit. The planet takes 637 Earth days to make 1 orbit around its star. This is probably the longest orbit of any planet that is in a 5 (or more) planet system. The other planets in the system, Kepler A B C & D were identified several years ago. Their orbits are much shorter. Kepler 150's orbit was harder to tease out, because it was hiding in the orbits of its sister planets. The oribtal signatures of the other 4 planets had to be subtracted out before Kepler 150's orbit could be nailed down. Switching to our beloved Moon now. Scientists at Brown University are studying the suignature of the aftermath of a volacno on the Moon called Ina. Previously, the eruption was thought to have taken place within the past 100 million years, 1 Billion years after volcanic activity on the Moon was thought to have ended. A caldera the sicentists are studying is testing everyone's theories. The caldera is much lighter than the surrounding area in which it lies, leading some scientists to speculate that this caldera is much younger than its surroundings. Because the caldera is much lighter, there is specualtion that it has not had as much time to collect the surrounding regolith, which is the layer of darker rock that accumulates over time. The 80 or so smooth rocks inside of Ina also confuses the issue. The lack of iimpact craters on these smooth hills also suggest Ina is younger the surrounding area, which has many more signs of impact. In their science, other astronomers used the amount of impact cratering in Ina to estimagte that the area saw volcanic activity 50 - 100 million years ago. But the scientists at Brown dispute these ideas. They compared Ina to Hawaii's Kilauea volcano in Hawai, and the aftermaths there from a 1959 eruption. In the Kilauea volcano, lava from the eruption solidified, then created a highly porous rock layer. This same process was thought to occur inside Ina's caldera, and it is this highly porous rock layer the Brown scientists say is responsible for hiding the amount of regolith in Ina. The porosity of the rock layer throws off the count of the craters, and is responsible for the caldera's relatively light color.