Thursday, August 16, 2018
The Ellensburg WA sky for the week of 8/18/18
Saturday: “The sky is black (or light polluted), the stars are white (or red or orange or yellow or blue), the whole world gazes upon the sight (except where there are too many city lights or people are lazy.” Wow. It is difficult to write a flowing set of lyrics when there are so many parenthetical thoughts. Most people think of the sky’s blackness as a lack of stars. But dark patches in the Milky Way are actually massive clouds of dust that are blocking the stars behind them. Two of the most prominent are dark nebulae B142 and B143 in the constellation Aquila the eagle. These are easy to find and enjoy with binoculars. First find the bright white star Altair, five fists held upright and at arm’s length above the southeast horizon at 10 p.m. Then move your binoculars up a little bit to the next bright star , about one fifth as bright. B142 and B143 are to the upper right of . They make an “E” shape in the sky; fitting because it was American astronomer E. E. Barnard who first proposed that these were dust clouds and not simply big spaces between the stars. For more information about dark nebula, including many more to look at with binoculars, go to https://goo.gl/9tiqdh.
Sunday: Venus is about a half a fist above the west-southwest horizon at 8:45 p.m. Jupiter is not far behind it, about one and a half fists above the southwest horizon.
Monday: Saturn is about a thumb width to the lower left of the Moon at 11 p.m., low in the south-southwest sky.
Tuesday: Mercury is a half a fist above the east-northeast horizon at 5:45 a.m.
Wednesday: Mars is about a fist to the lower left of the Moon at 11 p.m., low in the southern sky.
Thursday: Let’s all sing the galactic black hole monster song: “D is for dusty, that’s good enough for me. D is for dusty that’s good enough for me. D is for dusty that’s good enough for me. Oh dusty, dusty, dusty starts with D.” Astronomers know that spiral galaxies such as our own have super massive black holes in the center, black holes that are billions of times the mass of the Sun. They thought they got to be this massive by mergers where two galaxies collide and the gas, dust and black holes at the center of each colliding galaxy form a larger central black hole. But many distant galaxies show no signs of galactic mergers. Astronomers think the black holes at the center of these galaxies grew simply by snacking on the gas and dust that comes from supernova explosions and normal star formation. Just like the Cookie Monster gains weight by snacking on individual cookies rather than eating a cookie factory. Cookie crumbs, I mean dust, block your view of the center of our galaxy. It is about one fist above due south at 10 p.m., between the constellations Sagittarius and Scorpius. For more information, go to http://goo.gl/L9ppJf.
Friday: When the Moon is full, as it will be late tomorrow night, or close to full, it is difficult to see dim objects in the sky because of the sky glow. But why struggle to find dim objects when there is so much to see on the big, bright object in front of you? The lunar crater called Tycho is best seen during a full Moon. Tycho was formed about 109 million years ago when an asteroid struck the Moon, leaving a crater over 50 miles in diameter and ejected dust trails that radiate out hundreds of miles in all directions. For more lunar highlights, go to http://nightsky.jpl.nasa.gov/docs/ObserveMoon.pdf, a resource of the Night Sky Network.