Archive
06/29/2021 – Ephemeris – The Summer Triangle
This is Ephemeris for Tuesday, June 29th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:32, and it will rise tomorrow at 6:00. The Moon, 2 days before last quarter, will rise at 1:14 tomorrow morning.
Dominating the eastern sky at 11 pm are three bright stars. These are all first magnitude stars, members of the group of 21 brightest stars in the night sky. Highest, in the east, is Vega, the brightest of the three. It and a small, slim parallelogram of stars below it belong to the constellation of Lyra the harp. Below it to the northeast is Deneb, dimmest of the three at the head of the horizontally appearing Northern Cross, an informal constellation or asterism. Properly, Deneb is in the tail of Cygnus the swan flying south through the Milky Way. The third star of the three is Altair, lower still, but in the east-southeast at the head of Aquila the Eagle. These three stars are in a large asterism called the Summer Triangle, which will be with us through summer and fall.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT-4). They may be different for your location.
Addendum
The Summer Triangle finder animation showing first the unlabeled sky, Then the Summer Triangle with the stars labeled, then the constellations of those stars. Click on the image to enlarge it. Created using Stellarium and GIMP.
08/17/2020 – Ephemeris – The Milky Way’s Great Rift.
This is Ephemeris for Monday, August 17th. Today the Sun will be up for 13 hours and 56 minutes, setting at 8:44, and it will rise tomorrow at 6:49. The Moon, 1 day before new, will rise at 5:53 tomorrow morning.
High overhead the Milky Way is seen passing through the Summer Triangle of three bright stars. Here we find the Milky Way splits 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 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 easily seen in Aquila.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Great Rift finder animation as seen in the Summer Triangle, also showing the constellations of Cygnus the swan and the the northern part of Aquila the Eagle. This image a stack of 5 30 second exposures taken the morning of the Perseid meteor shower in a vain attempt to capture some meteors.
Annotated and animated photograph taken of Aquila August 13, 2018 during the Perseid meteor shower, the same night the image above. Taken by me and processed using Registax and GIMP.
08/10/2020 – Ephemeris – The celestial eagle: Aquila
This is Bob Moler with Ephemeris for Monday, August 10th. Today the Sun will be up for 14 hours and 15 minutes, setting at 8:55, and it will rise tomorrow at 6:41. The Moon, 1 day before last quarter, will rise at 12:20 tomorrow morning.
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 dominating the eastern sky in the evening now. 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 above and left of Aquila, flying in the opposite direction.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Aquila the Eagle in the southeastern sky. Created using Stellarium.
Annotated and animated photograph taken of Aquila August 13, 2018 during the Perseid meteor shower. Alas, no Perseids in this photograph. Taken by me and processed using Registax and GIMP.
Deneb with the other stars and constellations in the Summer Triangle. Created using Stellarium.
07/06/2020 – Ephemeris – The southernmost star of the Summer Triangle, Altair
This is Bob Moler with Ephemeris for Monday, July 6th. Today the Sun will be up for 15 hours and 25 minutes, setting at 9:30, and it will rise tomorrow at 6:05. The Moon, 1 day past full, will rise at 11:02 this evening.
The southernmost star of the Summer Triangle is Altair, high in the east-southeast. The other two stars of the triangle are Vega nearly overhead in the east, and Deneb high in the east-northeast. Altair is the closest of the three at a distance of 16.7 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 its rapid rotation. While it’s almost twice the sun’s diameter, it rotates once in about 9 hours, The CHARA Interferometer at Mt. Wilson has actually imaged its squashed disk in the infrared. Our Sun’s a slow poke, taking nearly a month to rotate once.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Summer Triangle. Created using Stellarium.
Lines added to show the rotation axis. Credit: Zina Deretsky, National Science Foundation.
06/12/2020 – Ephemeris – The Summer Triangle proclaims that summer is almost here
This is Bob Moler with Ephemeris for Friday, June 12th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:29, and it will rise tomorrow at 5:56. The Moon, 1 day before last quarter, will rise at 2:27 tomorrow morning.
Summer skies are coming. It’s only 8 days until summer officially arrives. It is a calendar day early this year because of the extra day added in February for the leap year. Looking to the eastern sky at 11 pm are three bright stars in a large triangle. The top star Vega is about half way up the sky to the zenith, and the brightest of the three. It’s in the small constellation of Lyra the harp. Lowest of the stars and just about due east is Altair in Aquila the eagle. Completing the triangle is Deneb in the northeast in the tail of Cygnus the swan or the head of the horizontal Northern Cross. These three stars make up the Summer Triangle. Be that as it may, the Summer Triangle will be in our evening sky moving slowly westward until December.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Finder animation for the Summer Triangle, seen in red for 11 pm, June 12th. Created using Stellarium and GIMP.
08/27/2019 – Ephemeris – The obscure constellation of Scutum the shield
Ephemeris for Tuesday, August 27th. Today the Sun will be up for 13 hours and 29 minutes, setting at 8:28, and it will rise tomorrow at 7:00. The Moon, 3 days before new, will rise at 4:23 tomorrow morning.
In the southern sky between the Teapot of Sagittarius below and Aquila the Eagle with its southernmost star of the Summer Triangle lies Scutum the shield of John Sobieski the Polish king who stopped the advance of the Turks at Kalenberg in 1683. The Polish half of me is very proud. Scutum is one of two official constellations which are related to real persons. The other one is Coma Berenices, a hank of the Egyptian Queen Berenice’s hair. However the stars here are so dim and embedded in the glow of the Milky Way as to be nearly impossible to discern. Scutum lies in one of the richest portions of the Milky Way, wonderful to scan with binoculars and telescopes for star clusters and nebulae or clouds of dust and gas.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Binocular and telescope deep sky objects in Scutum and Sagittarius. Created using Stellarium.
08/26/2018 – Ephemeris – The Great Rift
Ephemeris for Monday, August 26th. Today the Sun will be up for 13 hours and 32 minutes, setting at 8:30, and it will rise tomorrow at 6:59. The Moon, 3 days past last quarter, will rise at 3:13 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 to spot in Aquila the eagle.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Great Rift finder animation as seen in the Summer Triangle, also showing the constellations of Cygnus the swan and the the northern part of Aquila the Eagle. This image a stack of 5 30 second exposures taken the morning of the Perseid meteor shower the is year in a vain attempt to capture some meteors.
Annotated and animated photograph taken of Aquila August 13, 2018 during the Perseid meteor shower. Alas, no Perseids in this photograph. Taken by me and processed using Registax and GIMP.
08/14/2018 – Ephemeris – the constellation of Aquila the eagle
Ephemeris for Tuesday, August 14th. The Sun rises at 6:44. It’ll be up for 14 hours and 6 minutes, setting at 8:50. The Moon, 3 days past new, will set at 11:00 this evening.
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 dominating the eastern sky in the evening now. 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 its 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 above and left of Aquila, flying in the opposite direction. ……
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Animated Aquila finder chart. Created using Stellarium.
Annotated and animated photograph taken of Aquila August 13, 2018 during the Perseid meteor shower. Alas, no Perseids in this photograph. Taken by me and processed using Registax and GIMP.
Further notes on the Perseid meteor shower
I spent a good chunk of the Perseid peak night (August 12/13) at the Sleeping Bear Dunes National Lakeshore at the Dune Climb observing the Perseids. Though clear there was a great amount of haze in the air, part of which was smoke from the fires out west, and the barometric high we’ve been under for the past few days getting stagnant, The blue sky the day before was decidedly milky. Though the Milky Way overhead was visible, the teapot of Sagittarius below Saturn wasn’t.
A casual inspection of my photographs show only 2 Perseid meteors.
09/19/2017 – Ephemeris – The Great Rift
Ephemeris for Tuesday, September 19th. The Sun will rise at 7:26. It’ll be up for 12 hours and 18 minutes, setting at 7:45. The Moon, 1 day before new, will rise at 7:43 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 to spot in Aquila the eagle.
The times given 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.
07/17/2017 – Ephemeris – Constellations of the Summer Triangle III: Aquila the Eagle
Ephemeris for Monday, July 17th. Today the Sun will be up for 15 hours and 9 minutes, setting at 9:23, and it will rise tomorrow at 6:14. The Moon, 1 day past last quarter, will rise at 2:08 tomorrow morning.
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, the group of three bright stars dominating the eastern sky in the evening now. 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 above and left of Aquila, flying in the opposite direction.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Summer Triangle. Created using Stellarium and The Gimp.
Animated Cygnus finder chart. Created using Stellarium.
Bob Moler's Ephemeris Blog 