Archive
Ephemeris: 05/15/2025 – Finding Virgo the virgin in the spring sky
This is Ephemeris for Thursday, May 15th. Today the Sun will be up for 14 hours and 50 minutes, setting at 9:04, and it will rise tomorrow at 6:13. The Moon, 3 days past full, will rise at 12:36 tomorrow morning.
Located below the bright star Arcturus, high in the southeast, and below and left of Leo the lion, which is high in the south, lies the constellation of Virgo the virgin with its bright star Spica. Other than Spica, Virgo contains only dim stars. It’s quite large, extending to the upper right, and to the left of Spica. Virgo represents several goddesses. The Greek harvest goddess Persephone, whose Roman name is Ceres, which is the root of our word cereal, is one. The bright star Spica is the ear of wheat that she’s holding in her hand. Some see her standing at an odd angle, I see her reclining. Virgo also represents Astraea the goddess of Justice, with her scales, the constellation Libra, at her feet low in the southeast.
The astronomical event times given in this blog are for the Traverse City/Interlochen area of Michigan (Lat 44.7° N, Long 85.7° W; EDT, UT – 4 hours) unless stated otherwise. Times will be different for other locations.
Addendum
Ephemeris: 04/25/2025 – The star that opened a World’s Fair
This is Ephemeris for Arbor Day, Friday, April 25th. Today the Sun will be up for 13 hours and 59 minutes, setting at 8:40, and it will rise tomorrow at 6:39. The Moon, 2 days before new, will rise at 5:50 tomorrow morning.
High in the eastern sky at 10 tonight can be found the kite shaped constellation of Boötes the herdsman, chasing or herding the Great Bear Ursa Major of which the Big Dipper is the hind end, across the sky. The bright star at the base of the kite is the 4th brightest nighttime star, Arcturus. It can be found and name remembered by first locating the Big Dipper and by following the arc or curve of the handle to Arcturus. This star is an orange-colored giant star, 37 light years away. Its light was used to open the 1933 Chicago Worlds Fair believing its light left the star in 1893 the year of the previous Chicago Worlds Fair. It turns out that Arcturus is 3 light years closer than what they thought.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.
Addendum
For more on how they did it go to: https://chicagology.com/centuryprogress/1933fair54/
Ephemeris: 04/24/2025 – A constellation that’s a queen’s offering of her hair
This is Bob Moler with Ephemeris for Thursday, April 24th. Today the Sun will be up for 13 hours and 56 minutes, setting at 8:39, and it will rise tomorrow at 6:41. The Moon, 3 days before new, will rise at 5:29 tomorrow morning.
High in the east-southeast at 10 p.m. is a tiny and faint constellation of Coma Berenices, or Berenice’s hair. In it are lots of faint stars arrayed to look like several strands of hair. The whole group will fit in the field of a pair of binoculars, which will also show many more stars. The hank of hair was supposed to belong to Berenice, a real Queen of Egypt, of the 3rd century BCE who cut off her golden tresses and offered them to the gods for the safe return of her husband from war. Her husband did return safe, and at that same time her hair disappeared from the temple. The oracle of the temple pointed to this constellation showing that her sacrifice was enshrined in the stars.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.
Addendum
Ephemeris: 04/17/2025 – Finding the celestial crow
This is Ephemeris for Thursday, April 17th. Today the Sun will be up for 13 hours and 36 minutes, setting at 8:30, and it will rise tomorrow at 6:52. The Moon, 3 days before last quarter, will rise at 1:48 tomorrow morning.
The small constellation of Corvus the crow is located low in the south-southeast at 10:30 this evening. It’s made of 6 dim stars, but the pattern is a distinctive but distorted box with two stars at the upper left marking that corner, and another two marking the lower right corner. I usually don’t notice the extra star at these corners. To me the box stands out enough. It’s pretty much alone below Virgo and its bright star Spica, left an above it. I don’t see a crow here, but the box is distinctive in that no two sides are parallel. In the US we call the shape a trapezium. The British call it a trapezoid. Anyway it is a very interesting shape, at least to me.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.
Addendum
Ephemeris: 04/15/2025 – Hydra the water snake spans the spring skies
This is Ephemeris for Tuesday, April 15th. Today the Sun will be up for 13 hours and 30 minutes, setting at 8:28, and it will rise tomorrow at 6:56. The Moon, 3 days past full, will rise at 11:43 this evening.
Stretching from midway up the sky in the south-southwest to low in the southeast at 10 p.m. can be found the constellation of Hydra the water snake, the longest constellation of all. Unlike the monster of the same name that Hercules slew, this Hydra has but one head, which is its most distinctive part. The head of Hydra is located between the bright stars Procyon in the southwest, which is above the brighter star Sirius low in the sky, and Regulus in Leo the lion, higher in the south. Hydra’s head is a small but distinctive group of 6 stars that make a drooping loop to the right. The rest of Hydra wends its way in a crooked line from star to star, but within a reasonably straight path down to the southeastern horizon.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.
Addendum
Ephemeris: 03/31/2025 – Finding Leo, the celestial lion
This is Ephemeris for Monday, March 31st. Today the Sun will be up for 12 hours and 44 minutes, setting at 8:09, and it will rise tomorrow at 7:23. The Moon, 2 days past new, will set at 11:39 this evening.
At 10 p.m. the spring constellation of Leo the lion will be high in the south-southeast. It can be found by locating the Big Dipper high in the northeast and imagining that a hole were drilled in the bowl to let the water leak out. It would drip on the back of this giant cat. The Lion is standing or lying facing westward. His head and mane are seen in the stars as a backwards question mark. This group of stars is also called the sickle. The bright star Regulus is at the bottom, the dot at the bottom of the question mark. A triangle of stars, to the left of Regulus, is the lion’s haunches. Leo contains some nice galaxies visible in moderate sized telescopes. The stars in Leo’s part of the sky are fewer than those in the winter sky.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.
Addendum
Ephemeris: 03/27/2025 – Cancer the celestial crab
This is Bob Moler with Ephemeris for Thursday, March 27th. Today the Sun will be up for 12 hours and 32 minutes, setting at 8:04, and it will rise tomorrow at 7:30. The Moon, 2 days before new, will rise at 7:08 tomorrow morning.
At 10 PM, between the stars Castor and Pollux in Gemini high in the southwest and the star Regulus in Leo the Lion in the southeast lies the dimmest constellation of the zodiac, Cancer the crab. To me its 5 brightest stars make an upside down Y. There are the stars in the center of the constellation Asellus Borealis and Asellus Australis, the north and south donkeys. There’s a fuzzy spot between and just west of them called Praesepe, the manger, from which they are eating hay. In binoculars, it resolves into a cluster of stars called the Beehive cluster. We amateur astronomers also know it as M44, the 44th object on 18th century comet hunter Charles Messier’s list of fuzzy objects that might be mistaken for comets.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). Times will be different for other locations.
Addendum
Ephemeris: 02/27/2025 – The spring constellations are rising
This is Ephemeris for Thursday, February 27th. Today the Sun will be up for 11 hours and 5 minutes, setting at 6:28, and it will rise tomorrow at 7:21. The Moon is new today, and won’t be visible.
Today, we are exactly 3 weeks from the start of spring. The temperatures this week are rising. Even though at 8:00 PM Orion is high in the south, looking off to the east the spring constellation of Leo the lion has risen, and the Big Dipper is standing on its handle in the northeast. To the Anishinaabe native peoples of this area the Big Dipper is part of Ojiig, the Fisher, who brought summer to the Earth and when he’s in this position in the northeastern skies standing on his tail it is a sign of the spring to come and the start of the maple sugaring season. This next week or so is especially the best time, all year, to see the planet Mercury in the evening twilight due west, shortly after sunset. Its greatest separation from the Sun will come March 8th.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
Ephemeris: 02/25/2025 – Eridanus, a river in the sky
This is Ephemeris for Tuesday, February 25th. Today the Sun will be up for 10 hours and 59 minutes, setting at 6:25, and it will rise tomorrow at 7:24. The Moon, 2 days before new, will rise at 7:00 tomorrow morning.
One of the more obscure constellations around is Eridanus, which depicts a river. At 8 PM the river starts near the lower right corner of Orion, near the bright star Rigel and flows to the lower right then zigzags back down to the south-southwestern horizon, it then heads below the horizon. One has to travel to the far south to see the southern terminus of the river, the bright star Achernar. Writers over the ages have seen here the Nile and the Earth circling river Ocean of the ancient flat earth days. Achernar is actually two stars, the brightest was discovered to be the flattest star known, due to its rapid spin. The dimensions of Achernar A has been determined to be twice as wide across its equator than from pole to pole. It’s 139 light years away.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
Ephemeris: 02/21/2025 – Orion’s most distinctive feature
This is Bob Moler with Ephemeris for Friday, February 21st. Today the Sun will be up for 10 hours and 46 minutes, setting at 6:20, and it will rise tomorrow at 7:31. The Moon, 1 day past last quarter, will rise at 4:09 tomorrow morning.
Orion’s belt of three stars is one of the most noticeable star groupings in the sky. There are no other groups of three bright stars in a straight line visible anywhere else in the sky. The star’s names from left to right are Alnitak, Alnilam and Mintaka. They are actually a bit farther away than the other bright stars of Orion. Alnilam, the center star, is over three times the distance of red giant Betelgeuse above it and over twice as far as blue white giant star Rigel below it. Alnilam is 375 thousand times brighter than the Sun. These three stars were also known as Frigga’s Spindle by the Norsemen. Frigga, also known as Freya, is the goddess from whom we get the name of the day of the week we call Friday.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). Times will be different for other locations.
Addendum
Bob Moler's Ephemeris Blog 