08/18/2022 – Ephemeris – The Great Rift

This is Ephemeris for Thursday, August 18th. Today the Sun will be up for 13 hours and 54 minutes, setting at 8:43, and it will rise tomorrow at 6:49. The Moon, 1 day before last quarter, will rise at 12:02 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 star numbers drop off suddenly. This is especially easily seen in Aquila.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). 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 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.

07/18/2022 – Ephemeris – How to find the celestial eagle

This is Bob Moler with Ephemeris for Monday, July 18th. Today the Sun will be up for 15 hours and 8 minutes, setting at 9:23, and it will rise tomorrow at 6:15. The Moon, 2 days before last quarter, will rise at 12:33 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 that dominate 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 toward the eagle.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). They may be different for your location.

Addendum

Animated Aquila finder chart, also showing Cygnus the swan. The named stars are the stars of the Summer Triangle. Created using Stellarium.

Annotated and animated photograph taken of Aquila August 13, 2018 during the Perseid meteor shower. Alas, no Perseids in this photograph. The clouds of the Great Rift are easily visible. The red tinge of the image was due to the smoke haze from the wildfires in the western states. Taken by me and processed using Registax and GIMP.

07/05/2022 – Ephemeris – Taking a close look at Altair

This is Ephemeris for Tuesday, July 5th. Today the Sun will be up for 15 hours and 27 minutes, setting at 9:30, and it will rise tomorrow at 6:04. The Moon, 1 day before first quarter, will set at 1:12 tomorrow morning.

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 astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). They may be different for your location.

Addendum

Animated Aquila finder chart with Altair as its brightest star. Also shown are the other two stars of the Summer Triangle, Vega and Deneb. Created using Stellarium.

Credit: Zina Deretsky, National Science Foundation

06/27/2022 – Ephemeris – Finding the Summer Triangle

This is Ephemeris for Monday, June 27th. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:32, and it will rise tomorrow at 5:59. The Moon, 1 day before new, will rise at 5:13 tomorrow morning.

We’re nearly a week into summer, and the asterism or informal constellation called the Summer Triangle can be seen rising in the east as it gets dark. Highest of the three bright stars is Vega in the constellation Lyra the harp, whose body is seen in a narrow parallelogram nearby. The second star of the triangle is Deneb, in Cygnus the swan, lower and left of Vega, It appears dimmer than Vega because it is by far the most distant of the three. The third star of the Summer Triangle is seen farther below and a right of Vega. It is Altair in Aquila the eagle, and the closest. Altair is 16.5 light years away, Vega is 27 light years, while Deneb may be a whopping 2,600 light years away. One light year is 6 trillion miles (9 trillion kilometers).

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). 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. Created using Stellarium and GIMP.

07/09/2021 – Ephemeris – Finding the constellation of Aquila the eagle

This is Ephemeris for Friday, July 9th. Today the Sun will be up for 15 hours and 22 minutes, setting at 9:29, and it will rise tomorrow at 6:07. 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 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. It was said this was the eagle that attended the god Jupiter.

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

Animated Cygnus finder chart. Lyra the harp, Cygnus the swan, Delphinus the dolphin and Sagitta the arrow are also in the image. Can you find them? Click on the image to enlarge it. Created using Stellarium and GIMP.

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.