AstroTalk Episode January 19, 2017

Gravity, Pluto, Saturn and Monster Black Holes

3:02pm - 3:28pm

A discussion about gravity. Do earthquakes occur more often when the Moon is in its nearest orbit to the Earth? Some scientists think so. When the Moon is closest to the Earth, its gravity is 20 % stronger than when it is at its furthest point from the Earth. Some scientists believe when the Moon is at its closest to Earth, it tugs on fault lines and initiates earthquakes. Some scientists are also speculate that if an asteroid or meteor were captured, and then put in orbit around Earth, it could tug Earth further away from the Sun. This would be useful when the Sun expands, and then makes it too hot to live on Earth. Einstein's analysis of gravity and space time is also discussed. All these three topics have to do with gravity. New images of Pluto keep coming in, adding more data to Pluto's file. In the picture discussed, Pluto's surface resembles that of the Moon, with craters, uplands and valleys. A stunning picture of Saturn is also discussed. Scientists could never get this type of shot of Saturn's rings. It is taken from the Cassini spacecraft now in orbit around Saturn. The photo was taken with Cassini's Wide Angle Camera on October 28, 2016, in violet light. The photo is on the dim, sunlit side of Saturn, at a ring angle of about 25 degrees. A previously hidden black hole in NGC 1448 in an active galactic nuclei AGN is also featured. Gas and dust would usually hide this image, but this black hole gives itself away by emitting X-rays. The rays come from the black hole feeding on material behind the cloak of the gas and dust. The NUStar Telescope is able to detect the x-rays coming from area around this black hole. This black hole is super massive, weighing in at million times the mass of the Sun. An AGN is super bright, emitting light across the full electromagnetic spectrum. IC 3639, a galaxy with another sumpermassive black hole, is also being examined by these astronomers. Its light is detected beyond its obscuring gas and dust with NUStar. Both these galaxies are described as monsters or ogres under our bed, because we cannot see them, unless we use NUStar, of course.