Archive
08/28/2012 – Ephemeris – Altair, fatter in the middle
Ephemeris for Tuesday, August 28th. The sun will rise at 7:00. It’ll be up for 13 hours and 24 minutes, setting at 8:25. The moon, 3 days before full, will set at 4:54 tomorrow morning.
The southernmost star of the Summer Triangle is Altair, high in the south. The other two stars of the triangle are Vega nearly overhead, and Deneb high in the east. Altair is the closest of the three 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 9 hours, and has a decidedly squashed appearance when seen close up. There are techniques that can actually accomplish this. Our sun’s a slow poke, taking nearly a month to rotate once.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The constellations Lyra, Cygnus and Aquila. Created using Stellarium.
Check out Altair to the lower right.
08/17/2012 – Ephemeris – The constellation Aquila the eagle
Ephemeris for Friday, August 17th. The sun rises at 6:47. It’ll be up for 13 hours and 56 minutes, setting at 8:43. The moon is new today, and won’t be visible.
Aquila the eagle is a constellation that lies in the Milky Way. It’s in the southeastern sky as it gets dark. Its brightest star, Altair is one of the stars of the Summer Triangle, a group of three bright stars seen now in the eastern sky in the evening. Altair, in the head of the eagle, is flanked by two slightly dimmer stars, the shoulders of the eagle. The eagle is flying northeastward through the Milky Way. Its wings are seen in the wing tip stars. A curved group of stars to the lower right of Altair is its tail. Within Aquila the Milky Way shows many dark clouds as part of the Great Rift that splits it here. The other summer bird is Cygnus the swan, which I talked about earlier this year, above and left of Aquila, flying in the opposite direction.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The constellations Lyra, Cygnus and Aquila. Created using Stellarium.
08/25/11 – Ephemeris – The Great Rift
Thursday, August 25th. The sun rises at 6:56. It’ll be up for 13 hours and 35 minutes, setting at 8:31. The moon, 3 days before new, will rise at 3:57 tomorrow morning.
High overhead the Milky Way is seen passing through the Summer Triangle of three bright stars. Here we find the Milky Way split into two sections. The split starts in the constellation of Cygnus the Swan or Northern Cross very high in the east. The western part of the Milky Way ends southwest of the Aquila the eagle. This dark dividing feature is called the Great Rift. Despite the lack of stars seen there, it doesn’t mean that there are fewer stars there than in the brighter patches of the Milky Way. The rift is a great dark cloud that obscures the light of the stars behind it. Sometimes binoculars can be used to find the edges of the clouds of the rift, as stars numbers drop off suddenly. This is especially easy in Aquila.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Great Rift in the Milky Way. Created using Stellarium.
08/02/11 – Ephemeris – The constellation of Aquila the eagle
Note: this is a repeat due to Internet problems for the July 25th program with one alteration.
Tuesday, August 2nd. The sun rises at 6:29. It’ll be up for 14 hours and 37 minutes, setting at 9:06. The moon, 3 days past new, will set at 10:19 this evening.
The southernmost star in the Summer Triangle of three bright stars is Altair, high in the south southeast in the evening. It’s in the head of the constellation Aquila the Eagle. Altair is flanked by two stars, the eagle’s shoulders, and farther out are the wing tips. Other stars to the lower right are in its body and a last three in its tail. Near the tail binoculars will show a fuzzy spot that telescopes show as a compact star cluster, sometimes called the Wild Duck Cluster for its nearly triangular shape. Aquila is flying northeastward through the Milky Way, where it is split in two by a cloud of gas and dust, the edges of which can be seen in binoculars. According to mythology the Trojan boy Ganymede was taken to heaven at the behest of the god Zeus by this eagle.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Finder chart for M11, the Wild Duck Cluster, Created using Stellarium.
07/25/11 – Ephemeris – The constellation Aquila the eagle
Note: Due to a bad cable modem, this program was not uploaded in time for broadcast. It will be repeated at a later date.
Monday, July 25th. The sun rises at 6:21. It’ll be up for 14 hours and 55 minutes, setting at 9:16. The moon, 2 days past last quarter, will rise at 2:10 tomorrow morning.
The southernmost star in the Summer Triangle of three bright stars is Altair, high in the south southeast in the evening. It’s in the head of the constellation Aquila the Eagle. Altair is flanked by two stars, the eagle’s shoulders, and farther out are the wing tips. Other stars to the lower right are in its body and a last three in its tail. Near the tail binoculars will show a fuzzy spot that telescopes show as a compact star cluster, sometimes called the Wild Duck Cluster for its nearly triangular shape. Aquila is flying northeastward through the Milky Way, where it is split in two by a cloud of gas and dust. According to mythology the Trojan boy Ganymede was taken to heaven at the behest of the god Zeus by this eagle.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Bob Moler's Ephemeris Blog 