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Ephemeris: 03/20/2026 – Spring begins today!
This is Ephemeris for Friday, March 20th. Today the Sun will be up for 12 hours and 9 minutes, setting at 7:55, and it will rise tomorrow at 7:43. The Moon, 2 days past new, will set at 10:21 this evening.
At 10:46 AM today the season of spring will begin. It may or may not feel it in our neck of the woods, but astronomically at that time the Sun will appear to cross a point in the sky called the vernal equinox. Equinox means equal night, when the Sun is up for 12 hours, and set for 12 hours. It does, if you don’t look too closely, and in the old days clocks weren’t that accurate anyway. The vernal equinox is the point in the sky where the Sun crosses the celestial equator, which is above the Earth’s equator heading north. The North Pole will begin 6 months of daylight, while the rest of the Northern Hemisphere will bask in more than 12 hours of sunlight a day. The reverse is true in the Southern Hemisphere where autumn will start.
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; EST, UT – 5 hours) unless stated otherwise. Times will be different for other locations.
Addendum
Ephemeris: 03/20/2025 – Spring has sprung!
This is Ephemeris for Thursday, March 20th. Today the Sun will be up for 12 hours and 10 minutes, setting at 7:55, and it will rise tomorrow at 7:43. The Moon, 2 days before last quarter, will rise at 2:57 tomorrow morning.
At 5:02 AM this morning the Sun passed overhead on the Earth’s equator heading northward beginning the season of spring. It is called the vernal or spring equinox also the March equinox if you didn’t care which hemisphere you lived in. Anyway, our daylight hours become longer and longer until June 21st the first day of summer. We have been seeing the effects of all this because all winter long the daylight hours have been getting longer and now in the last few weeks our temperatures have begun to rise, especially last Friday and Saturday. Along with the increased daylight hours the Sun is also getting higher in the sky giving us a more concentrated heating, it’s light and heat not being spread out as much as it was during the winter.
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: 03/29/2024 – Calculating the date of Easter
This is Ephemeris for Good Friday, March 29th. Today the Sun will be up for 12 hours and 39 minutes, setting at 8:07, and it will rise tomorrow at 7:26. The Moon, 3 days before last quarter, will rise at 1:09 tomorrow morning.
Easter will be celebrated by Western Christian churches this Sunday. Easter is a movable feast in that it falls on a different date each year following the first full moon of spring. It was an attempt to follow the Jewish Passover, which starts on the 15th of the month of Nisan. The Jewish calendar being a lunar calendar, the 15th is generally the night of the full moon, sometimes called the Paschal Full Moon. And since the Last Supper was a Seder, according to at least one Gospel, the Christian church wanted to link Easter with Passover as closely as possible using the Roman solar based (Julian) calendar. That’s not always the case, especially with our current Gregorian Calendar. Passover this year begins at sunset April 22nd because the Jewish lunar calendar is tied to the Julian Calendar.
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
Ephemeris: 03/19/2024 – Today is the last day of winter and the first night of spring
This is Ephemeris for Tuesday, March 19th. Today the Sun will be up for 12 hours and 8 minutes, setting at 7:54, and it will rise tomorrow at 7:44. The Moon, 2 days past first quarter, will set at 6:13 tomorrow morning.
Today, at least in daylight, is the last day of winter. Tonight will be the first night of spring, since spring will arrive at 11:07 pm tonight. This is when the Sun crosses the celestial equator heading northward in the sky, which is actually the Sun moving so it passes overhead and moving north of the equator on the Earth. This gives us in the Northern Hemisphere longer days and warmer temperatures. We call it the vernal or spring equinox. However since some folks are living south of the equator, and are starting autumn at the same time. We sometimes call it the March equinox to recognize that fact. From now until June 20th the Sun will be moving higher in our sky and be staying out longer each day.
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
Ephemeris: 12/15/2023 – Jupiter is seen in Aries this year, also precession
This is Bob Moler with Ephemeris for Friday, December 15th. Today the Sun will be up for 8 hours and 49 minutes, setting at 5:02, and it will rise tomorrow at 8:13. The Moon, 3 days past new, will set at 7:50 this evening.
The planet Jupiter is seen against the stars of the constellation Aries the ram this year. The four stars of the constellation are seen above it, two of which are bright enough to be fairly easily seen. The other two are quite dim. The brightest is the star called Hamal. It is as bright as one of the stars of the Big Dipper. Aries used to be the constellation at the beginning of the Zodiac, where the Sun entered on the first day of spring. That honor has now moved westward to the western part of Pisces, the fish. The reason it has changed in the 1900 years since Ptolemy set up the Zodiac in the second century is that the Earth’s axis wobbles and the astrological signs of the Zodiac move with the seasons rather than the stars.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.
Addendum
03/21/2023 – Ephemeris Extra – Spring has sprung without me
Being in the hospital and now in inpatient rehab one loses a sense of time. So the vernal equinox snuck by me unnoticed. My view of the outside world is another part of the hospital, a part of the HVAC system, and a piece of sky.
Yesterday, the Sun passed over the Earth’s equator, heading northward. The Sun is gradually setting at the South Pole and rising at the North Pole. Folks like me who live in the Northern Hemisphere are experiencing longer daylight than those south of the equator, who are beginning autumn. The daylight hours will increase daily until June 21st, the summer solstice. In the Interlochen/Traverse City area, that will be 15 hours and 34 minutes.
The cause of the Earth’s seasons is not our varying distance from the Sun in our eliptical orbit of the Sun of 93 million plus or minus a million and a half miles.By the way, the Earth is currently moving away from the Sun. It will be farthest from the Sun around July 4th or 5th.
Our perception of the advance of spring, besides the gradully warming temperatures and increasing daylight hours, will be the height of the Sun’s path in the sky, and the position of the Sun’s rise and set points on the horizon. All these annual changes are angles having to do with one’s latitude (an angle), Earth’s position in orbit (an angle), and the tilt of the Earth’s axis to it’s orbit (more angles).
Bob
03/18/2022 – Ephemeris – Spring is two days away!
This is Ephemeris for Friday, March 18th. Today the Sun will be up for 12 hours and 3 minutes, setting at 7:52, and it will rise tomorrow at 7:47. The Moon, at full today, will rise at 8:28 this evening.
Sunday morning March 20th, at 11:33 am the Sun will cross overhead at the earth’s equator as it appears to head north, starting for us, the season of spring. It will be the vernal equinox. As you can tell from my intro, we’re already above 12 hours of daylight, and we’ll add another 3 plus hours of daylight before summer begins in three months. We are already adding about 3 minutes a day of daylight to that goal now, the maximum rate. With the Sun out longer and its ascension higher in the sky each day, it is rapidly adding energy to the Northern Hemisphere. We won’t feel that immediately. While the land rapidly absorbs heat, the oceans and lakes, especially the Great Lakes, are big heat sinks, taking much longer to warm up.
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 Earth from 2 days before the vernal equinox 2018, with the North Pole not quite in sunlight. I’ve added a magnifying spot showing Michigan. It was a rare clear day when this image was taken. Credit NOAA/DSCOVR satellite/EPIC camera. The DSCOVR satellite is located in a halo orbit around the Sun-Earth Lagrange L1 point nearly a million miles sunward of the Earth.
Earth’s position at the solstices and equinoxes. This is a not to scale oblique look at the Earth’s orbit, which is nearly circular. The Earth is actually farthest from the Sun on July 4th. The dates for the equinoxes and solstices are shown one day later than it is actually. Click on the image to enlarge. Credit: ESO (European Southern Observatory), which explains the captions in German and English.
The Sun’s path through the sky on an equinox day from the Traverse City/Interlochen area in Michigan. The Sun is plotted every 15 minutes. This is a stereographic projection which compresses the image near the zenith and enlarges the image towards the horizon. Created using my LookingUp program.
03/17/2022 – Ephemeris – We have 12 hours of daylight and night today, three days early
This is Ephemeris for St. Patrick’s Day, Thursday, March 17th. Today the Sun will be up for 12 hours even, setting at 7:51, and it will rise tomorrow at 7:49. The Moon, 1 day before full, will set at 8:20 tomorrow morning.
Why is this the day of equal day and night, when the vernal equinox, which means “equal night” is still three days away? The difference is due to our atmosphere and our definition of sunrise and sunset. Our atmosphere makes objects near the horizon appear higher than they actually are, which hastens sunrise and retards sunset. Also, the instant of sunrise and sunset is when the top of the sun appears to touch the horizon, rather than when the Sun bisects the horizon. Plus, it’s moving about a degree a day (twice its diameter) against the stars. So by the time of the equinox, on Sunday the 20th, the time between sunrise and sunset will have progressed to 12 hours and 9 minutes. But it was close enough for the ancients who coined the term.
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
This works for the Interlochen area. It may be a different by a day for other locations, but for the northern latitudes, it will be before the true equinox day, March 20th here.
How the atmosphere bends the light of the Sun or Moon rising or setting to appear higher than it actually is. S is the actual position of the Sun, S’ is the apparent position of the Sun. The blue line is the observer O’s horizon. The gray line is the actual, though much exaggerated, light path bent or refracted by the Earth’s atmosphere. The black line is the apparent sight line to the Sun. Credit Francisco Javier Blanco González, 2017
03/19/2021 – Ephemeris – Enjoy this last full day of winter!
This is Ephemeris for Friday, March 19th. Today the Sun will be up for 12 hours and 7 minutes, setting at 7:54, and it will rise tomorrow at 7:45. The Moon, 2 days before first quarter, will set at 2:23 tomorrow morning.
Spring is almost here. It will arrive at 5:37 tomorrow morning, so this is the last full day of winter, such as it was. That point in time and the point in the sky where the Sun crosses the celestial equator, the imaginary line in the sky above the Earth’s equator, heading northward is called the vernal equinox. Vernal means spring and equinox means equal night, meaning that day and night are equal, which they actually were last Tuesday. Since western civilization has spread south of the equator where the seasons are reversed, our Northern Hemisphere spring equinox is the Southern Hemisphere’s autumnal equinox, so to be understandable to both hemispheres we generally say March or September equinox instead.
Addendum
The Sun’s path through the sky on an equinox day from the Traverse City/Interlochen area in Michigan. The Sun is plotted every 15 minutes. This is a stereographic projection which compresses the sky near the zenith and enlarges the sky toward the horizon. Created using my LookingUp program.
04/07/2020 – Ephemeris – Today is the Paschal full moon
This is Ephemeris for Tuesday, April 7th. Today the Sun will be up for 13 hours and 6 minutes, setting at 8:18, and it will rise tomorrow at 7:09. The Moon, at full today, will rise at 7:55 this evening.
Tonight’s full moon is the Paschal full moon, the first full moon of spring which is tomorrow in the Holy Land, so Passover begins at sunset tomorrow. Easter for western churches falls on the first Sunday after the first full moon of spring, which is this next Sunday the 12th. Orthodox Easter rule adds that it must fall after Passover,a week long observance, which pushes their Easter celebration to a week later, April 19th. Both Christian churches attempt to mimic the Jewish Lunar Calendar by setting Easter by the first full moon of spring using solar based calendars and assuming that spring started on March 21st. This year actual spring started on the 20th in the Holy Land, and 19th here by 10 minutes, in our Gregorian Calendar and 13 days earlier by the old Julian Calendar. This is all very complicated.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Bob Moler's Ephemeris Blog 