Wednesday, September 16, 2015
The Ellensburg WA sky for the week of 9/19/15
Saturday: “You know Aries and Cancer and Draco and Libra. Leo and Pisces and Virgo and Hydra. But, do you recall, the pointiest asterism of all? Triangulum, the three sided asterism, had a very pointy edge….” Sorry. Some stores have started sending out their Christmas catalogues and that has put me in the mood to modify some Christmas songs. Anyway, Triangulum is a small constellation between the more prominent Andromeda and Aries. Its main feature is a skinny triangle oriented parallel to and nearly four fists held upright and at arm’s length above the east horizon at 10 p.m.
Sunday: Venus is at its brightest for this viewing cycle. You’ll have no trouble finding it two and a half fists above the east horizon at 6 a.m. In fact, you could probable wait until 6:30 a.m., just a few minutes before sunrise and still see it three fists above the east-southeast horizon.
Monday: There is a rumor (started by my dog and me) that The Beach Boys are working on a new solar system-themed record. I bet the first single will be “Catch a Wave and You’re Sitting on Top of Titan.” As the seasons change on this large moon of Saturn, astronomers are looking for signs of the winds increasing. They’ll send the Cassini spacecraft on a flyover of Kraken Mare, a large liquid hydrocarbon sea, to see if there are any waves. The NASA Jet Propulsion Laboratory has made a “Titan Great Lakes” tour video that you can find at http://goo.gl/ndXDhd. Available lakefront property and the potential for large waves. Who is up for a “Surfin' Safari”? Saturn is one and a half fists above the southwest horizon at 7:30 p.m.
Tuesday: To celebrate the start of school at Central Washington University tomorrow, let’s sing a song of the season. “Oh the weather outside is grand. And the fire is rightfully banned. There is really no place to go. Let it snow, let it snow, let it snow. On Mars.” The Mars Reconnaissance Orbiter has discovered evidence of carbon dioxide snow clouds high above the surface of Mars. Carbon dioxide, also called “dry ice”, exists in Mars south polar ice cap and requires temperatures of nearly 200 degrees below zero Fahrenheit to form. Astronomers were not sure how this polar cap gets replenished but the discovery of carbon dioxide clouds may provide an answer. For more information, go to http://goo.gl/shMTf. Mars is two fists above the east horizon at 6:00 a.m., just above the bright star Regulus and halfway between the very bright planets Venus above it and Jupiter below it.
Wednesday: At precisely 1:21 a.m. PDT, the center of the Sun crosses the celestial equator and passes into the southern sky. The celestial equator is an imaginary line that divides the sky into a northern and southern half. When the Sun is in the southern half of the sky, it appears to take a shorter path from rising to setting. It also does not get as high in the sky at noon. This leads to shorter days and longer nights. Since the Sun crosses the celestial equator today, there is an instant when it is equally in the northern and southern sky, called the north and south celestial hemispheres. This so-called “equal night” is given by the Latin word equinox. Thus, today is known as the Autumnal Equinox. However, the day and night are not of equal duration today. The sun rises at 6:49 a.m. and sets at 7:00 p.m. Day and night are closest to equal duration on Saturday.
Thursday: The bright star Arcturus is three fists above the west horizon at 7:30 p.m.
Friday: Fomalhaut, the most isolated bright star, is about one and a half fists above the south horizon at 11:30 p.m. It is the first magnitude star furthest from any other first magnitude stars. First magnitude stars represent the approximately twenty brightest stars.
The positional information in this column about stars and planets is typically accurate for the entire week. For up to date information about the night sky, go to http://nightsky.jpl.nasa.gov/planner.cfm.