Starwatch for April 2019
Written by Karl Hricko on April 9, 2019
Hello! I’m Karl Hricko of United Astronomy Clubs of N J and the National Space Society bringing you the April Starwatch for the WNTI listening area.
When you throw a ball, it eventually falls to the ground. The phenomenon that prevents objects from leaving the Earth is called gravity. Gravity is defined as the natural attraction between bodies. It holds the planets in orbit around the Sun and keeps the Moon in orbit around Earth. It holds together stars in galaxies, and galaxies in superclusters of galaxies, and therefore is responsible for many of the structures in the Universe. Gravity has an infinite range, although its effects become increasingly weaker on farther objects.
Einstein described gravity a lot differently. He said that it was not a force, but a result of the curvature of the fabric on space-time. That means it could be likened to a bowling ball sitting on a trampoline and pushing it downward – making a depression or a gravity well. Just a few years later, some scientists postulated that gravity might be carried by particles called “gravitons”.
Whatever the case might be, the planets are still seen in the sky as they orbit the Sun due to gravity. After sunset in the west, Mars can be seen in Taurus. Mercury and Venus are both out of view. At dawn, looking south, Saturn is visible in Sagittarius, and Jupiter is in Ophiuchus. So while you observe the effect of the Sun’s gravity on the planets, you can also appreciate the effect of the Earth’s gravity on your feet.
Until our next Starwatch –don’t forget to check out …what’s up in the night sky!