Ephemeris: 12/25/2023 – This year’s Christmas Stars
Merry Christmas! This is Ephemeris for Christmas Day, Monday, December 25th. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:07, and it will rise tomorrow at 8:18. The Moon, 1 day before full, will set at 8:25 tomorrow morning.
The real star of Bethlehem is probably not what is popularly depicted as a bright star in the sky, rather it was something subtle, only noticed by some astrologers. However, gracing our skies tonight we do have, in the morning and again in the evening, two bright star-like objects. I call them star-like objects because they’re planets. In the morning we have brilliant Venus off in the southeast at 7:30 in the morning, and early in the evening we have bright Jupiter in the south. Jupiter is bright enough that when Venus is not in the sky it is sometimes mistaken for it, although Venus would never be seen in the south* in the evening, it’s always too close to the Sun. Again have a Merry Christmas!
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.
* Except from the North Pole. From there all directions are south.
Addendum
Ephemeris: 12/22/2023 – Jupiter and Venus as the Star of Bethlehem
This is Ephemeris for Friday, December 22nd. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:05, and it will rise tomorrow at 8:17. The Moon, 3 days past first quarter, will set at 4:53 tomorrow morning.
Many writers of the 2nd and 3rd centuries AD place Jesus’ birth around 2 BC, which had to be before Herod the Great’s death, which I suggest was in 1 BC marked by a total lunar eclipse. So the Star of Bethlehem could appear several years later than the triple conjunction of Jupiter and Saturn in 7 BC that’s been popular. In 3 and again in 2 BC there were star-like conjunctions or apparent joining of the planets Jupiter and Venus against the backdrop of the constellation of Leo the Lion. A lion is related to Judah, son of Jacob by a blessing the latter gave his 12 sons in Genesis. The first conjunction occurred in August of 3 BC in the morning sky. On June 16th of the next year the two planets got together again, this time in the evening sky, a month or more after Jesus would have been born in the lambing season of spring.
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
Ephemeris: 12/21/2023 – Winter comes late this evening
This is Bob Moler with Ephemeris for Thursday, December 21st. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:04, and it will rise tomorrow at 8:17. The Moon, 2 days past first quarter, will set at 3:37 tomorrow morning.
Today is mostly the last day of Fall, since the moment of solstice will arrive at 10:28 pm (03:28 on the 22nd UTC). If you’re south of the equator this is the first day of summer. The Earth reaches a point in its orbit where its North Pole is tipped its furthest away from the Sun, and is in shadow in the middle of its six-month night. The Sun for us is up only 8 hours, 48 minutes, and to boot the Sun only rises 22 degrees above the horizon giving us the least amount of energy of any day of the year. Why did the ancients celebrate this time of year? That’s because the Sun had slowed and stopped its drift southward and was beginning to come back higher in the sky. Spring and summer would eventually return!
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
Ephemeris: 12/20/2023 – Where are the naked-eye planets this week?
This is Bob Moler with Ephemeris for Wednesday, December 20th. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:04, and it will rise tomorrow at 8:16. The Moon, 1 day past first quarter, will set at 2:21 tomorrow morning.
Let’s find out where the naked-eye planets have wandered off to this week. Three of those five planets are now visible, but Mercury sets too close to sunset to be seen. And Mars rises too close to sunrise. Saturn and Jupiter are the only evening planets visible. Saturn can be seen moving from low in the south-southwest to setting in the west-southwest at 10:19 pm. Jupiter will be moving from the high in the southeast to the west-southwest, and will be up most of the night until 3:53 am. The slightly waxing gibbous Moon will be seen to the right of Jupiter tonight. Venus, the brilliant morning star, will rise in the east-southeast at 4:56, am, and be a brilliant beacon in the morning, shining in the southeast by 7 am.
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
Ephemeris: 12/19/2024 – Jupiter is our bright evening Christmas star but what about 7 BC?
This is Bob Moler with Ephemeris for Tuesday, December 19th. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:04, and it will rise tomorrow at 8:16. The Moon, at first quarter today, will set at 1:06 tomorrow morning.
This year Jupiter is our bright evening Christmas star. But what about the one described in the Bible, in the Gospel of Matthew? We will look today at the first of two events that may have been recorded as the Star of Bethlehem. In 7 BC there was a rare event over 8 months when three times the planet Jupiter passed Saturn against the stars of the constellation Pisces. Could the Persian astrologer priests called Magi, have read into the event enough significance to start the journey to Jerusalem in search of the newborn King of the Jews? It was the scribe’s readings that then sent them to Bethlehem. It is thought that Pisces was associated with the Hebrews, Jupiter with the Messiah or world ruler, and Saturn with the peoples of Palestine.
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
The normal motion of the sun, moon and planets in the sky is to the east, or to the left in this diagram. Jupiter takes a bit less than 12 years to orbit the sun while Saturn takes a bit less than 30 years, so Jupiter will pass Saturn about every 20 years. However, when they are both at opposition of the sun when they do that and closest to the earth, they will appear to move backwards for a time. This is called retrograde motion from their normal eastward motion. Jupiter being closest to us and closer to the Earth’s speed makes a bigger retrograde loop than Saturn does. So when they’re both at opposition when they cross paths we get a triple conjunction like this.
Ephemeris: 12/18/2023 – The Moon tonight
This is Bob Moler with Ephemeris for Monday, December 18th. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:03, and it will rise tomorrow at 8:15. The Moon, 1 day before first quarter, will set at 11:50 this evening.
Tonight’s Moon is just about exactly one day before first quarter it’s a six-day-old Moon. Each quarter of the revolution of the moon is just about one week. A lunar month comes out to 29 1/2 days which is a little bit more than 28 days which should be four weeks. That’s pretty close. The illuminated part of the moon that we’re looking at first quarter I consider the most interesting half of the Moon with a good mixture of lowlands which are the seas which are the dark grayer parts of the Moon and the highlands which are very roughly cratered, and are actually higher than the lowlands, or the seas. So if you could put water on the Moon without evaporating it, this is where the water would be. Early telescopic astronomers did think that’s where the water was. Of course the Moon has no atmosphere and the water would just evaporate.
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
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
Ephemeris: 12/14/2023 – The Geminids will still be near peak tonight
This is Ephemeris for Thursday, December 14th. Today the Sun will be up for 8 hours and 50 minutes, setting at 5:02, and it will rise tomorrow at 8:13. The Moon, 2 days past new, will set at 6:31 this evening.
The Earth will pass through the heart of the Geminid meteoroid stream at about 2 this afternoon, so this evening is probably the best time to be able to see these meteors. They will appear to come from the northeastern to eastern sky in the evening. The Geminids are now the most active annual shower. This hasn’t always been the case, but the meteor rate has been increasing in recent years. Our problem with it is that it happens in December when, number one it’s cold, and number 2 it’s pretty cloudy. I must admit I’ve never seen a Geminid for those reasons. This year, it seems to have been clearer than previous years, so maybe we might get a glimpse at them. Stragglers of the Geminids can be seen until almost Christmas.
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
The Geminids are supposed to reach about 120 an hour at peak which would be at one or two in the morning which is about 12 hours after their actual peak. So that we won’t get the 120, but there’s an equal chance to spot them on the night of the 13/14th or 14/15th. Click or tap on the image to enlarge it. Image created using my Looking Up app.
Ephemeris: 12/13/2023 – Where are the naked eye planets this week?
This is Bob Moler with Ephemeris for Wednesday, December 13th. Today the Sun will be up for 8 hours and 50 minutes, setting at 5:02, and it will rise tomorrow at 8:12. The Moon, 1 day past new, will set at 5:22 this evening.
Let’s find out where the naked-eye planets have wandered off to this week. Three of those five planets are now visible, but Mercury sets too close to sunset to be seen. And Mars rises too close to sunrise. Saturn and Jupiter are the only evening planets visible. Saturn can be seen moving from low in the south-southwest to setting in the west-southwest at 10:44 pm. Jupiter will be moving from the high in the southeast to southwest, and will be up most of the night until 4:22 am. Venus, the brilliant morning star, will rise in the east-southeast at 4:40 am, and be a brilliant beacon in the morning, shining in the southeast by 7 am. Tonight is the first of two nights when the Geminid meteor shower will be at its peak.
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
Ephemeris: 12/12/2023 – The source of the Geminid meteor shower
This is Bob Moler with Ephemeris for Tuesday, December 12th. Today the Sun will be up for 8 hours and 51 minutes, setting at 5:02, and it will rise tomorrow at 8:11. The Moon is new today, and won’t be visible.
The Geminid meteor shower, which will peak this Thursday, is caused by a small body called 3200 Phaethon which looks like an asteroid but has the orbit of a comet, coming close to the Sun and back out to the asteroid belt. It’s probably a dead comet, with all the volatiles sublimated away leaving only the rocky bits. It is named Phaethon, because at the time it was the asteroid that came closest to the Sun. In Greek mythology Phaethon, the son of Helios the Sun god borrowed his father’s chariot that carried the Sun to take it out for a spin one day with disastrous results. The Geminid meteor shower was first recognized in 1862. The hourly rates of the Geminids have increased every year since then. The meteor stream has completely filled in the orbit of Phaethon, and they’re being pushed around by the gravitational effect of the planets and the pressure of sunlight.
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
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