Archive
Ephemeris: 03/17/2025 – When the largest telescope in the world was in Ireland
This is Ephemeris for St. Patrick’s Day, Monday, March 17th. Today the Sun will be up for 12 hours and 1 minute, setting at 7:51, and it will rise tomorrow at 7:49. The Moon, 3 days past full, will rise at 11:40 this evening.
In the 19th century Ireland laid claim to having the largest telescope in the world. It was a reflecting telescope with a mirror diameter of 72 inches. It was built by William Parsons the Third Earl of Rosse. The base of the telescope tube rested in a pit between two massive walls and could only look to either side of a north-south direction. It saw first usage in 1847. The telescope was called the Leviathan of Parsonstown, and was in use until 1890. Mirrors in those days were made of a silvery alloy called speculum. Two mirrors were used alternately because speculum tarnished. The mirror not in use would have to be re-polished and swapped in from time to time. It was the largest telescope until the 100 inch at Mt. Wilson was put in service in 1917.
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: 03/14/2025 – Viewing today’s eclipse from the Moon
This is Ephemeris for Pi Day, Friday, March 14th. Today the Sun will be up for 11 hours and 51 minutes, setting at 7:48, and it will rise tomorrow at 7:54. The Moon, at full today, will rise at 8:27 this evening.
I hope you had a good look at the eclipse this morning I don’t know if it was clear or cloudy because I’m recording this last Sunday night. One entity got a cloudless shot at seeing the eclipse without any obstructions. That was the Blue Ghost lander on Mare Crisium on the Moon. However, it was on the Moon so it was seeing a total eclipse of the Sun. I’ll be really interested to see the photographs coming back from that. There was a satellite and one lander, the Surveyor 3 Lander on the Moon that took pictures of the Earth during the solar eclipse. Of course, we saw a lunar eclipse. It just saw a ring of light around the Earth where the Sun’s light was being bent through the Earth’s atmosphere into it’s shadow to dully illuminate the Moon.
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
Sorry, I couldn’t spend any time on the program to celebrate Pi day, so I’ll give it a token appreciation here:
Update
Firefly Aerospace.
Ephemeris: 03/13/2025 – Get ready for tomorrow morning’s total lunar eclipse
This is Ephemeris for Thursday, March 13th. Today the Sun will be up for 11 hours and 48 minutes, setting at 7:46, and it will rise tomorrow at 7:56. The Moon, 1 day before full, will set at 8:06 tomorrow morning.
Late, late, late, tonight, or actually early tomorrow morning there will be a total eclipse of the Moon. The moment of full moon, which is necessary for a lunar eclipse will occur at 2:55 AM tomorrow, and the middle of the eclipse will be 5 minutes later. The partial phase of the lunar eclipse will start at 1:10 AM. This partial phase will grow until 2:26 AM when totality will begin. During this period of time the Moon should have a dull reddish color because it is illuminated only by the light filtering through the Earth’s atmosphere from the combined sunrises and sunsets around the world at that time. The total phase will end at 3:31 AM. The ending partial phase will continue until 4:48 AM.
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: 03/12/2025 – Last chance to see four naked-eye planets in the evening
This is Ephemeris for Wednesday, March 12th. Today the Sun will be up for 11 hours and 45 minutes, setting at 7:45, and it will rise tomorrow at 7:58. The Moon, 2 days before full, will set at 7:49 tomorrow morning.
Let’s take our weekly look at the whereabouts of the naked-eye planets. At 8:30 PM this evening four of the five naked eye planets will be out. Starting from the West we have Venus the brightest of all. Left and a bit below is the much dimmer Mercury. Both will rapidly disappear in evening twilight in a less than a week. Venus will pass in conjunction with the Sun on March 22nd, Mercury will do the same two days later. Jupiter, the second-brightest planet will be high in the southwest. Mars, the third-brightest planet now, with its distinctive reddish hue, is high in the south-southeast, below and right of the stars Castor and Pollux in Gemini. By the end of the month only two planets, Mars and Jupiter will be left in the evening 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: 03/11/2025 – There will be a lunar eclipse early Friday morning
This is Ephemeris for Tuesday, March 11th. Today the Sun will be up for 11 hours and 42 minutes, setting at 7:44, and it will rise tomorrow at 8:00. The Moon, 3 days before full, will set at 7:32 tomorrow morning.
Early Friday morning, the 14th there will be a total eclipse of the Moon. Of course, we all hope for clear skies, but this is March. About 12:30 AM, keen observers might notice that the lower left side of the Moon seems to be a bit dimmer than the opposite side rather than the Moon being evenly illuminated. That’s because that leading edge of the Moon is witnessing a partial eclipse of the Sun. The moon is in the Earth’s penumbra or partial shadow where the Sun is being gradually cut off from the eastern part of the moon to the western part. The partial phase will begin at 1:10 AM Friday morning. Totality will begin at 2:26 AM and last until 3:31 AM. The ending partial phase will continue to 4:48 AM.
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
I don’t show the Moon when it enters or leaves the penumbra is because nothing is noticeable. About a half hour before the Moon enters the umbra to begin the partial phase of the eclipse, the side of the Moon nearest the umbra will be noticeably duller than the other side. The same is true after the partial phase is over. The effect of the deepening penumbra is more easily seen in sunglasses, that will darken the still bright Moon.
Ephemeris: 03/10/2025 – Aristarchus, the brightest spot on the Moon, but not tonight
This is Ephemeris for Monday, March 10th. Today the Sun will be up for 11 hours and 39 minutes, setting at 7:42, and it will rise tomorrow at 8:01. The Moon, 4 days before full, will set at 7:11 tomorrow morning.
The moon tonight is bright. The sunrise line or terminator on the moon is crossing the large gray plain called Oceanus Procellarum, the largest of the moon’s seas. These seas were figments of the first telescopic observer’s imagination. They are really huge impact basins into which interior lava flowed. On the left edge of the Moon, just below center, this evening, at the terminator is a small shadow filled crater that might be visible in binoculars, but definitely telescopes. It’s called Aristarchus. It is a fairly new crater, probably less than a billion years old. As a rule the brighter the crater the newer it is. Aristarchus is the brightest spot on the Moon, when it is full. Visual astronomers have seen hazes and bright spots on rare occasions in and near Aristarchus.
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
Aristarchus tonight, March 10, 2025, on the terminator (left), and Friday night, the 14th, before the total lunar eclipse starts. The enlargements show the telescopic view. Created using Stellarium, LibreOffice Draw and GIMP. The Moon doesn’t actually appear larger on the 14th. Apparently my field of view changed while getting the 14th’s image.
Ephemeris: 03/07/2025 – GTAS Meeting tonight (also on Zoom): Previewing 3/14’s total lunar eclipse
This is Ephemeris for Friday, March 7th. Today the Sun will be up for 11 hours and 29 minutes, setting at 6:38, and it will rise tomorrow at 7:07. The Moon, 1 day past first quarter, will set at 4:28 tomorrow morning.
The Grand Traverse Astronomical Society will host its February meeting tonight at 8 PM at Northwestern Michigan College’s Joseph H Rogers Observatory. The talk for the evening will be given by yours truly. One week from today, Friday, March 14th in the early morning hours, there will be a total eclipse of the Moon. That is my subject. I will explore some notable lunar eclipses of the past, what they are, and why we don’t see them every full moon. I’ll talk about other facts about lunar eclipses. The observatory is located on Birmley Rd. South of Traverse City between Garfield and Keystone roads. The meeting will also be available via Zoom. Instructions to join the meeting will be on the society’s website, gtastro.org.
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: 03/06/2025 – The Moon at first quarter
This is Ephemeris for Thursday, March 6th. Today the Sun will be up for 11 hours and 26 minutes, setting at 6:37, and it will rise tomorrow at 7:09. The Moon, at first quarter today, will set at 3:31 tomorrow morning.
The Moon is indeed at first quarter today with the instant of being 90° from the Sun coming at 11:32 this morning. To me the first quarter moon is the best time to view because there are a lot of craters that are visible in deep shadow. The terminator, the sunrise line, on the Moon cuts the disk in half and a lot of craters can even be seen in binoculars. With a small telescope the jumble of craters provides a wonderful view of the destruction of the early bombardment of the Moon in its early days. The reason the Moon has all these craters and the Earth does not is the fact that the Earth has an active surface with volcanoes, plate tectonics, water and wind to erode and deform the surface. The Moon has really none of that.
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: 03/05/2025 – Taking our weekly look at the whereabouts of the naked-eye planets
This is Ephemeris for Ash Wednesday, March 5th. Today the Sun will be up for 11 hours and 23 minutes, setting at 6:36, and it will rise tomorrow at 7:10. The Moon, 1 day before first quarter, will set at 2:21 tomorrow morning.
Let’s take our weekly look at the whereabouts of the naked-eye planets. At 7:10 PM this evening four of the five naked eye planets will be out. Starting from the West we have Venus the brightest of all. Below it at the 7 o’clock position and halfway to the horizon is the much dimmer Mercury, three days from its greatest separation from the Sun. Jupiter, the second-brightest planet will be high in the south-southwest below and right of the Moon tonight. The 4th planet out is Mars, the third-brightest planet now, with its distinctive reddish hue, west of the stars Castor and Pollux in Gemini, and in the southeast. By the end of the month both Venus and Mercury will be gone out of the evening sky, leaving only two, Mars and Jupiter.
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: 03/04/2025 – Looks like asteroid 2024 YR4 will miss the Earth
This is Ephemeris for Fat Tuesday, March 4th. Today the Sun will be up for 11 hours and 20 minutes, setting at 6:35, and it will rise tomorrow at 7:12. The Moon, 2 days before first quarter, will set at 1:02 tomorrow morning.
I’ve got some good news for a change. The recently discovered small asteroid with the provisional designation 2024 YR4 it’s not going to hit the Earth on December 22nd, 2032. More precisely the percentage chance of hitting the Earth is now down to four thousandths of a percent. The recalculation was due to observations from the Subaru Telescope in Hawaii. Three separate organizations calculated the chances of the asteroid to hit. That means this number is of very high confidence. The new center of the locus that they calculated for the asteroid’s passage by the Earth now comes closer to the orbit of the Moon than it does the Earth. So that’s one less thing to worry about, although astronomers will be keeping tabs on it.
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
