Monday, July 29, 2013
The Ellensburg sky for the week of 8/3/13
Saturday: It’s a moonless August morning. The first remnant of dawn has not appeared yet. Suddenly, you notice a large softly radiant pyramid of light in the east sky. The base of this ghostly triangle is along the east horizon and the peak stretches two or three fists held upright and at arm’s length above the horizon about two hours before sunrise. Don’t be scared. It’s not really a ghost. It is an effect called the zodiacal light. This light comes from sunlight reflecting off dust grains in our solar system. The effect is the most visible when the band of constellations called the zodiac makes a steep angle with the horizon. You need a clear dark sky with no haze or light pollution to see the zodiacal light. At its brightest, the zodiacal light rivals the light of the central Milky Way. This is one of the best times of year to see the zodiacal light in the morning.
This is also one of the best times of the year to see meteors. The Perseid meteor shower peaks early next week. But you should see increased meteor activity later this week just below the W of the constellation Cassiopeia. This point is about two and a half fists held upright and at arm’s length above the northeast horizon at 11 p.m. By dawn, this point is about seven fists above the northeast horizon
Sunday: At 9 p.m., Venus is about a half a fist above the west horizon and Saturn is two fists above the southwest horizon. How’s that for an uncreative description of the night sky?
Monday: 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/GRrWa.
Tuesday: Hercules stands almost directly overhead at 10:30 this evening. Four moderately bright stars form a lopsided square that represents his body, while his head points southward.
Wednesday: School starts in about a month so it is time to start reviewing your geometric shapes. Let’s start with the right triangle that is a fist above the west-southwest horizon at 10 p.m. The bluish star Spica is at the right angle, in the lower left corner of the triangle. Saturn is a half a fist above Spica and Mars a fist to the right of Spica.
Thursday: First mentioned exactly a month ago, Bellatrix Lestrange is Sirius Black’s cousin. But, far from being kissing cousins. They are killing cousins. Bellatrix kills Sirius in a fight at the Ministry of Magic. Bellatrix the star is the third brightest star in the constellation Orion the hunter. You can find it two fists above the east horizon at 5 am. But, don’t turn you back on it!
Friday: When you got up early yesterday, you may have noticed a very bright point of light two and a half fists to the left of Bellatrix and two fists above the east horizon. That is the planet Jupiter. Mars is a fist to the lower left of Jupiter. Continue following the line from Jupiter to Mars and you’ll reach the elusive Mercury. It is less than a half a fist above the northeast horizon.
The positional information in this column about stars and planets is typically accurate for the entire week.