Archive
09/29/11 – Ephemeris – Deneb at the zenith
Thursday, September 29th. The sun will rise at 7:37. It’ll be up for 11 hours and 49 minutes, setting at 7:27. The moon, 2 days past new, will set at 8:28 this evening.
At 10 p.m. tonight the first magnitude star Deneb will be overhead, that is very near the zenith. Deneb is the northern most and dimmest of the three stars of the Summer Triangle. It is at the head of the Northern Cross, which extends to the south. This is an asterism, which is what astronomers call a informal constellation. The Big and Little Dippers are also examples of asterisms. You won’t find them in the list of the 88 official constellations. The actual constellation that Deneb belongs to is Cygnus the swan. In the swan Deneb is the tail. That’s actually what Deneb means. The swan is flying southwestward along the Milky Way with its wings outstretched. Stars can be followed around the wings to make out a very realistic flying swan.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Deneb at the Zenith. Looking overhead while facing south. Created using Stellarium.
The Summer Triangle of bright stars Deneb, Vega and Altair are in this view.
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.
07/21/11 – Ephemeris – The constellation of Cygnus the swan
Thursday, July 21st. Today the sun will be up for 15 hours and 3 minutes, setting at 9:20. The moon, 2 days before last quarter, will rise at 11:56 this evening. Tomorrow the sun will rise at 6:17.
High in the east northeast as it gets dark flies the constellation of Cygnus the swan. This constellation is also known as the Northern Cross. The cross is seen lying on its side with the bright star Deneb at the head of the cross to the left. The rest of the cross is delineated in the stars to the right. As a swan, Deneb is the tail, the stars of the crosspiece of the cross are the leading edges of wings as Cygnus flies south through the Milky Way. There are faint stars that also define the tips and trailing edges of its wings. It is a very good portrayal of a flying swan, like the mute swans we see on the wing. In Cygnus we are looking in the direction that the sun and the earth are traveling as we orbit the center of the Milky Way.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Cygnus The Swan Created using Stellarium.
Click to enlarge.
Bob Moler's Ephemeris Blog 