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08/30/11 – Ephemeris – The bright star Altair
Tuesday, August 30th. The sun will rise at 7:02. It’ll be up for 13 hours and 20 minutes, setting at 8:23. The moon, 2 days past new, will set at 8:48 this evening.
The Summer Triangle of bright stars is visible overhead and to the south.. Vega is highest, nearly overhead, while Deneb is high in the northeast. The southernmost star of the Summer Triangle is Altair. Altair is the closest of the three stars at a distance of 16.8 light years away. One light year is nearly 6 trillion miles. Altair is 10 times the brightness of the sun. If seen at Altair’s distance, the sun would only be as bright as one of the two stars that flank it. What is rather different about Altair is it’s rapid rotation. While its almost twice the sun’s diameter, it rotates once in only 6 ½ to 10 hours, and would show a decidedly squashed appearance if seen close up. Our sun’s a slow poke, taking nearly a month to rotate just once.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
07/19/11 – Ephemeris – The brightest stars visible now in the evening
Tuesday, July 19th. Today the sun will be up for 15 hours and 6 minutes, setting at 9:21. The moon, half way from full to last quarter, will rise at 11:11 this evening. Tomorrow the sun will rise at 6:15.
Let’s check out all the bright stars in the evening sky, as it gets dark tonight. High in the west is the bright yellow-orange star Arcturus. In the northwest is the Big Dipper, whose curved handle points to Arcturus. Straightening that curve to a spike will point to Spica a blue-white star low in the southwest. The bright star to its right isn’t. It’s the planet Saturn. In the south is the red star Antares which usually twinkles merrily. High in the east is the bright white star Vega. To its lower right is Altair, and to its lower left the star Deneb. Vega, Altair and Deneb make the Summer Triangle, whose rising in the east signals the coming of summer. Always present for us in northern Michigan is Capella very low in the north.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Bright Summer Stars. Created using Stellarium.
Click on the image to enlarge. This is a whole sky chart. The round edge is the horizon. BTW the star Capella, very low in the north, is a winter star, but it’s visible all year round for folks north of 44 degrees north latitude.
Bob Moler's Ephemeris Blog 