2018-08-01. The Kepler Revolution.

posted Aug 5, 2018, 1:03 PM by Alan Gould
By Kimberly M. S. Cartier, Eos/AGU. For GSS A Changing Cosmos chapter 8. Excerpt: The Kepler Space Telescope will soon run out of fuel and end its mission. Here are nine fundamental discoveries about planets aided by Kepler in the 9 years since its launch. ...Kepler Space Telescope, a small spacecraft that opened a large window to the many thousands of exoplanets strewn throughout the Milky Way ...was exhibiting the first signs of low fuel and ... would be functional for only a few more months. Its fuel tank hit critically low levels on 2 July, and mission scientists put Kepler into a no-fuel hibernation mode until its latest round of data can be downloaded on 2 August. ...1. Planets Are Everywhere, Equally. ...Through its unblinking gaze, Kepler discovered 4,571 planetary signatures, 2,327 of which have been confirmed as actual exoplanets. ...2. The Solar System May Not Be Unique. ...With the help of an artificial intelligence algorithm, Kepler discovered another star with the same number of planets as our solar system. The star, Kepler-90, is 2,545 light-years away and slightly hotter than the Sun. Seven of its eight planets were discovered in 2013, and the elusive eighth planet rounded out the set in December 2017. The data show that the orbits of all eight Kepler-90 exoplanets fit within Earth’s orbit around the Sun. ...3. Earth May Not Be Unique. ...So far, astronomers have confirmed 29 exoplanets less than twice the diameter of Earth that fall in or near their star’s habitable zone, a region of space surrounding a star that has the right temperature to keep water in a liquid state on the surface of a planet. Seventy more possible Earth cousins remain as candidate exoplanets until astronomers can verify them. ...4. An Earth-Sized Planet May Not Be Earth-Like. ...Worlds likely to be covered with molten lava abound in the Kepler data set. ...Kepler found plenty of ocean worlds, too. ...Kepler-22b, discovered in 2011, was the first example. ...7. Planets Exist in Unlikely Places. ...Kepler found that exoplanets can orbit two, three, or even four stars with relative ease. ...8. Planets Follow Defined Trends and Come in Distinct Groups. ...planets smaller than Neptune fall into two distinct and separate categories, like two branches of a family tree. The branches were already familiar to astronomers—rocky super-Earths and gaseous mini-Neptunes—but astronomers now know that the categories represent a more fundamental planet property. ...9. Planets and Stars Can Be Oddballs.... https://eos.org/features/the-kepler-revolution