Archive
Ephemeris: 06/30/2025 – Asteroid hitting the Moon in 2032 may cause spectacular meteor shower and danger to satellites
This is Ephemeris for International Asteroid Day, Monday, June 30th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:32, and it will rise tomorrow at 6:01. The Moon, 2 days before first quarter, will set at 12:46 tomorrow morning.
This is the 117th anniversary of the Tunguska Event, an asteroid strike that hit Siberia in 1908. An asteroid, thought to be of similar size, will pass close to the Earth, but has a 4% chance of hitting the Moon on December 22nd 2032. The asteroid was discovered near the end of last year and has the designation 2024 YR4. For a while there was a fear that this asteroid might hit the Earth. However, it was soon found that the asteroid would not hit the Earth but had a chance of hitting the Moon. Recently a paper was written that looked at what would happen to the ejecta of an impact of this asteroid on the Moon. It could be a hazard to the satellites orbiting the Earth.
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
Further reading
The Mother of All Meteor Showers Could Threaten Satellites By Evan Gough, Universe Today
Original paper: The Potential Danger to Satellites due to Ejecta from a 2032 Lunar Impact by Asteroid 2024 YR4 by Paul Wiegert et al.
Ephemeris: 06/27/2025 – Star party tomorrow night at the Sleeping Bear Dunes
This is Ephemeris for Friday, 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, 2 days past new, will set at 11:44 this evening.
Weather permitting, the Grand Traverse Astronomical Society and the Park Rangers will host a star party at Sleeping Bear Dunes National Lakeshore, at the Dune Climb starting around 9:00 PM. The parking lane closest to the dune will be blocked off for telescopes. Note… the start time is before actual sunset, however the Moon should be visible from near sunset and after until nearly 11 PM Also on tap will be binary stars, an interesting treat through the telescope. The Rangers leave around 11:00 PM however if it stays clear and there’s enough interest, society members with their telescopes will stay longer. Two other star parties are planned this summer: on July 26th and August 23rd.
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: 06/26/2025 – Finding the famous Double-Double Star
This is Ephemeris for Thursday, June 26th. 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 past new, will set at 11:12 this evening.
I generally will talk about observing something in the sky, in this program, if it can be seen with the naked eye, or can be seen in binoculars near something that can be seen with the naked eye, or something that can be seen in a small telescope that is visible in binoculars, near a naked eye object. This is of the latter type. High in the east at 11:00 PM or so is the bright star Vega. Just to the left of it in is a faint star, best seen in binoculars. It’s barely visible to the naked eye as a single star. But binoculars will show that it’s two star of equal brightness. However, viewing it with a telescope using probably the most power the telescope is capable, each of those stars is doubled again so Epsilon Lyrae is the famous Double-Double Star. It’s quite a challenge for a small telescope. This is also the time of the latest sunset and end of evening twilight. The last vestige of the glow moves to the north and ends just after midnight.
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
Bonus: A telescope capable of splitting the components of Epsilon should be capable of spotting the Ring Nebula (M57). It is not, however, visible in binoculars or a telescope finder. But it’s easily found by pointing the telescope between the two bottom stars of the Lyra parallelogram. Created using Stellarium, LibreOffice Draw and GIMP.
Ephemeris: 06/25/2025 – Taking our weekly look at the naked-eye planets
This is Ephemeris for Wednesday, June 25th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58. The Moon is new today, and won’t be visible.
Let’s take our weekly look at the whereabouts of the naked-eye planets. The Red Planet Mars, will be seen to the upper left of the bright star Regulus in the constellation Leo the lion. Both are seen in the western sky by 10:30 PM at least. At that time Mercury might be spotted low on the west-northwestern Lake Michigan horizon. This is not a favorable appearance of Mercury. Jupiter passed conjunction with the Sun yesterday, but it will be nearly a month before it will appear in our morning sky. Venus will rise at 3:34 AM in the east northeast, and by 5 AM will be seen low in the east, as the Morning Star. By then Saturn will be in the southeast, having risen 2 hours earlier.
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
Venus and Saturn at 5 AM tomorrow morning, June 26th, 2025, in the east-southeastern sky. Created using Stellarium.
Ephemeris: 6/24/2025 – Lyra, the heavenly harp
This is Ephemeris for Tuesday, June 24th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58. The Moon, 1 day before new, will rise at 5:36 tomorrow morning.
Fairly high in the east at 11 p.m. can be found a bright star just above a small, narrow, but very distinctive parallelogram of stars. They are the stars of the constellation Lyra the harp. The bright star is Vega, the 5th brightest nighttime star. To the Romans, the star Vega represented a falling eagle or vulture. Apparently they never made the distinction between the two species. It is a pure white star and serves as a calibration star for color and brightness. In the evening, it is the top-most star of the Summer Triangle. The harp, according to Greek mythology, was invented by the god Hermes. The form of the harp, in the sky, is as he had invented it: by stretching strings across a tortoise shell. Hermes gave it to his half-brother Apollo, who in turn gave it to the legendary musician Orpheus.
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: 06/23/2025 – The Big Dipper is tearing itself apart
This is Ephemeris for Monday, June 23rd. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:32, and it will rise tomorrow at 5:58. The Moon, 2 days before new, will rise at 4:33 tomorrow morning.
The usual impression is to think that the stars of a constellation are actually located close together. This is usually not true. The stars of a constellation can be at vastly different distances. The Big Dipper is different. The five stars, excepting the two end stars of the dipper and 12 other dimmer stars in the general area are of similar distance and have the same motion through space. The group is called the Ursa Major Moving Cluster or Ursa Major Association, and is moving about 9 miles per second relative to the solar system to the east. An association is a rather loose, sparse star cluster. This association lies about 80 light years away. If it were five and a half times farther away, it would be the same distance as the Pleiades.
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: 06/20/2025 – Summer begins tonight!
This is Ephemeris for Friday, June 20th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:57. The Moon, 2 days past last quarter, will rise at 2:38 tomorrow morning.
Summer will officially arrive for us on Earth’s Northern Hemisphere at 10:42 pm, tonight. If you are south of the equator, winter will arrive. If you are listening to this on the Internet from two time zones east of the Eastern United States it’s 2:42 UT, June 21st. And to be season agnostic, it’s the June solstice. From tonight to the December solstice, the first day of winter for us northern hemispherians, (I think that’s a word) the daylight hours will get shorter as the Sun heads south. Solstice means “Sun standstill” as it stops its northerly motion and will, after tonight, head back south again. The Northern Hemisphere will still be heating up for another month, before we begin to cool down.
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: 06/19/2025 – Finding the Serpent Bearer in the heavens
This is Ephemeris for Juneteenth, Thursday, June 19th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:57. The Moon, 1 day past last quarter, will rise at 2:15 tomorrow morning.
The red star Antares shines low in the south-southeast at 11 PM in the constellation of Scorpius. In the area of sky above and to the left lies a large constellation of faint stars called Ophiuchus, the serpent bearer. The constellation shape is like a large bell, which reminds me of the head, shoulders and arms of a fellow that’s holding the snake stretched out across his body. The serpent he’s holding is Serpens, the only two-part constellation in the heavens. The head rises to Ophiuchus’ right, and the tail extends up to the left. In Greek myth, Ophiuchus represents the great physician Aesculapius, educated by the god Apollo, and the centaur Chiron, who is found in the stars as Sagittarius, just rising below him.
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: 06/18/2025 – Three of the five naked-eye planets are visible now
This is Ephemeris for Wednesday, June 18th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:56. The Moon, at last quarter today, will rise at 1:55 tomorrow morning.
Let’s take our weekly look at the whereabouts of the naked-eye planets. The Red Planet Mars, will be seen just to the upper left of the bright star Regulus in the constellation Leo the lion. Both are seen in the western sky by 10:30 PM at least. They are currently about the same brightness, but Mars has an orange-reddish hue, while Regulus, is blue-white. They are a good color contrast, especially in binoculars which will increase their brightness. Even before 5 AM Venus will be seen very low in the east, as the Morning Star. The waning crescent Moon will be near Saturn, having passed it around midnight. By 5 AM Saturn will be to the right and below it. Venus will be visible until close to 5:40.
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
Venus, Saturn and the waining crescent Moon at 5 AM tomorrow morning, June 19th, 2025, in the east. Created using Stellarium.
The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on June 18, 2025. The night ends on the left with sunrise on the 19th. Click or tap on the image to enlarge it. Created using my LookingUp app and GIMP.
Ephemeris: 06/17/2025 – Finding the naked-eye double star Mizar and Alcor
This is Ephemeris for Tuesday, June 17th. Today the Sun will be up for 15 hours and 34 minutes, setting at 9:31, and it will rise tomorrow at 5:56. The Moon, 1 day before last quarter, will rise at 1:36 tomorrow morning.
In tonight’s sky, the Big Dipper is high in the northwest hanging from its handle. In its handle is a star or two that are fascinating. It’s the star at the bend in the handle. It’s called Mizar. Next to it, for those with good eyesight, is a dimmer star, called Alcor. The name Mizar is from the Arabic, meaning apron or cover, while Alcor means the forgotten one. In ancient times the ability to actually see both stars was a test for good eyesight, especially for Arabic warriors. The pair is also known as the “Horse and the Rider”. Some Native American tribes saw the handle stars as hunters tracking the Great Bear, Ursa Major, of which the Big Dipper is a part, rather than its very unnatural tail. Dim Alcor became a hunting dog.
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 
