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Ephemeris: 05/23/2025 – M13, The Great Hercules Star Cluster
This is Ephemeris for Friday, May 23rd. Today the Sun will be up for 15 hours and 6 minutes, setting at 9:13, and it will rise tomorrow at 6:05. The Moon, halfway from last quarter to new, will rise at 4:13 tomorrow morning.
The constellation Hercules the hero can be found between the bright stars Vega which is fairly low in the east northeast and Arcturus high in the southeast. It’s about 1/3 of the way from Vega to Arcturus. His most distinctive feature is the keystone a box of four stars wider at the top than the bottom. Along the western edge of the keystone can be seen, sometimes with the naked eye, but better with binoculars as a small spot about 1/3 of the way down from the top star to the bottom star. It looks like a fuzzy spot. In telescopes smaller than 8 inch diameter, at least with my eyes, it stays fuzzy, but in larger telescopes it begins to crystallize out into a myriad of stars. It is the Great Hercules Globular Star Cluster. Number 13 on late 18th century astronomer Charles Messier’s catalog of fuzzy objects that weren’t the comets he was looking for. We know it as Messier 13, or M13.
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: 05/22/2025 – Finding Hercules among the spring stars
This is Bob Moler with Ephemeris for Thursday, May 22nd. Today the Sun will be up for 15 hours and 5 minutes, setting at 9:12, and it will rise tomorrow at 6:06. The Moon, 2 days past last quarter, will rise at 3:51 tomorrow morning.
In the eastern sky at 11 PM about a third of the way along the line from the bright star Vega in the east northeast and Arcturus high in the southeast is the constellation of Hercules the hero. It’s kind of hard to spot, although it’s one distinctive feature is the box of four stars called the Keystone of Hercules which means it’s wider at the top than at the bottom. That is his body. He’s upside down in the sky according to how they draw the picture of Hercules. Most of his stars are reasonably dim. This is the great hero of Greek myth. While in the winter sky the bright and splashy constellation of Orion the hunter, was kind of a hard luck hero, with no real accomplishments. Hercules has an astronomical jewel that I’ll talk about tomorrow.
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: 05/21/2025 – Checking where the naked-eye planets are
This is Bob Moler with Ephemeris for Wednesday, May 21st. Today the Sun will be up for 15 hours and 3 minutes, setting at 9:11, and it will rise tomorrow at 6:07. The Moon, 1 day past last quarter, will rise at 3:32 tomorrow morning.
Let’s take our weekly look at the whereabouts of the naked-eye planets. At 10 PM this evening two naked eye planets will be out. Jupiter, is now low in the west-northwestern sky. The rapidly fading Mars, with its distinctive reddish hue, is in the west-southwest, at that time. Once it’s darker binoculars can be used to spot the Beehive Star Cluster to its lower right. By 5 AM Venus will be seen very low in the east, as the Morning Star, with Saturn and the waning crescent Moon in an upward line to the right and a bit above it. Venus will require a low eastern horizon then. But it will rise and be visible until close to 5:45 or later. For those with telescopes, Saturn’s rings are now opening up again, and will for the next 7 years.
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: 05/20/2025 – Corona Borealis, Ariadne’s Crown
This is Ephemeris for Tuesday, May 20th. Today the Sun will be up for 15 hours and 1 minute, setting at 9:10, and it will rise tomorrow at 6:08. The Moon, at last quarter today, will rise at 3:12 tomorrow morning.
There are two bright stars in the eastern part of the sky. High in the southeast at 11 PM is Arcturus, and in the east northeast, lower down is the star Vega. A third of the way between Arcturus and Vega is a small arc of stars called Corona Borealis, the northern crown. It is a small constellation. The brightest star in it is called Alphecca. According to Greek mythology it is the crown given to Princess Ariadne, daughter of King Minos of Crete. Of interest in the next year or so is a possibility of a nova or bright star appearing just south of that arc of stars for about a week. It is a recurrent nova, which explodes about every 80 years. The last time was in 1946, so the next time would be within the next year or so. And astronomers are breathlessly waiting for that to happen.
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: 05/19/2025 – Finding Libra the scales
This is Ephemeris for Monday, May 19th. Today the Sun will be up for 14 hours and 59 minutes, setting at 9:09, and it will rise tomorrow at 6:09. The Moon, 1 day before last quarter, will rise at 2:51 tomorrow morning.
Libra the scales or balance is a dim constellation which is seen low in the southeast in the evening now. It is one of the constellations of the Zodiac. The term Zodiac means circle of animals, so Libra doesn’t exactly fit. The ancient Babylonians recognized it. Back then it may have represented the equality of day and night because the Sun would have been at the autumnal equinox in Libra at that time. The early Greeks, and possibly the Arabs, did not see Libra as being separate from the constellation of Scorpius the scorpion, which is rising to its lower left. Its two brightest stars have Arabic names meaning north claw and south claw. Scorpions have claws, and last I’ve checked, balances do not.
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
A bit of trivia: At 14 letters Zubeneschamali is the longest star name.
In a previous post I noted that Libra was associated with Virgo which also represents Astraea the goddess of Justice, with Libra, being her Scales of Justice.
Ephemeris: 05/16/2025 – Two bright stars, alike but different
This is Bob Moler with Ephemeris for Friday, May 16th. Today the Sun will be up for 14 hours and 52 minutes, setting at 9:05, and it will rise tomorrow at 6:12. The Moon, halfway from full to last quarter, will rise at 1:21 tomorrow morning.
Two stars which I’ve been known to confuse in the twilit sky in late spring and late summer are Arcturus and Vega. These stars have about the same brightness and in some lists of stars swap places between the 4th and 5th brightest stars in the sky. Arcturus is an orangish star, now high in the southern sky in the evening, while Vega is a pure white star which to my eyes tends towards a little tinge of blue. Vega is high in the south, actually almost overhead, in the late summer. Now, in mid to late Spring Vega is rather low in the northeastern sky. Arcturus is a cool star on the outside which has depleted the hydrogen in its core and is a red giant star, while the younger and more massive Vega, still turning hydrogen into helium.
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: 05/14/2025 – Looking for the naked-eye planets
This is Bob Moler with Ephemeris for Wednesday, May 14th. Today the Sun will be up for 14 hours and 48 minutes, setting at 9:03, and it will rise tomorrow at 6:14. The Moon, 2 days past full, will rise at 11:41 this evening.
Let’s take our weekly look at the whereabouts of the naked-eye planets. At 10 PM this evening two of the five naked eye planets will be out. Jupiter, is now the brightest evening planet, our substitute evening star if you will. It will be in the low in the west-northwestern sky. The rapidly fading Mars, with its distinctive reddish hue, is in the west-southwest, less than a binocular field’s width east of the Beehive Star Cluster in Cancer the Crab. By 5 AM Venus will be seen very low in the east, as the Morning Star. It will require a low eastern horizon. It should be visible until close to 6 AM. Saturn is visible to the right and a bit above Venus. It will disappear much sooner than the much brighter Venus.
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. Event times will be different for other locations.
Addendum
Ephemeris: 05/07/2025 – Taking our weekly look at the whereabouts of the naked-eye planets
This is Ephemeris for Wednesday, May 7th. Today the Sun will be up for 14 hours and 31 minutes, setting at 8:55, and it will rise tomorrow at 6:22. The Moon, 3 days past first quarter, will set at 4:36 tomorrow morning.
Let’s take our weekly look at the whereabouts of the naked-eye planets. At 10 PM this evening two of the five naked eye planets will be out. Jupiter, is now the brightest evening planet, our substitute evening star if you will. It will be in the low in the west-northwestern sky. The rapidly fading Mars, with its distinctive reddish hue, is in the west-southwest, moving away from the stars Castor and Pollux in Gemini to the lower right of it. By 5:30 AM Venus will be seen very low in the east, as the Morning Star. It will require a low eastern horizon. It should be visible until a bit after 6:30. Saturn is visible close and to its right and a bit above. It will disappear much sooner than Venus.
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: 05/05/2025 – A brief early morning meteor shower
This is Bob Moler with Ephemeris for Cinco de Mayo, Monday, May 5th. Today the Sun will be up for 14 hours and 26 minutes, setting at 8:53, and it will rise tomorrow at 6:25. The Moon, 1 day past first quarter, will set at 4:03 tomorrow morning.
The Earth is now passing through a stream of bits of rock that were shed from Halley’s Comet on its many previous passes through the inner solar system. The Earth gets to pass through this stream twice a year, Once in late October as the stream passes the Earth’s orbit heading in, and in early May as the stream is departing. The peak of this meteor shower, the Eta Aquariids, is this afternoon. Since the meteoroids are coming from nearer the direction of the Sun, there is only a short period when these meteors are visible. Actually less than an hour between moonset at 4:03 AM and nearly 5 AM around here as twilight begins to interfere with the display. The meteors will seem to come from low in the east-southeast, but they will be seen all over the sky.
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: 04/30/2025 – Let’s take our weekly look at the whereabouts of the naked-eye planets
This is Bob Moler with Ephemeris for Wednesday, April 30th. Today the Sun will be up for 14 hours and 13 minutes, setting at 8:46, and it will rise tomorrow at 6:32. The Moon, 3 days past new, will set at 1:08 tomorrow morning.
Let’s take our weekly look at the whereabouts of the naked-eye planets. At 9:30 PM this evening two of the five naked eye planets will be out. Jupiter, is now the brightest evening planet, our substitute evening star if you will. It will be in the western sky. Tonight it will be below the crescent Moon. To its lower left, the great constellation of Orion will be beginning to set. The rapidly fading Mars, with its distinctive reddish hue, is high in the southwest, with the stars Castor and Pollux in Gemini to the right of it. By 5:30 AM Venus will be seen very low in the east, as the Morning Star. It will require a low eastern horizon. It should be visible until a bit after 6:30. Saturn is visible close and to its lower right.
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
Bob Moler's Ephemeris Blog 