Archive
12/06/2021 – Ephemeris – A new comet is reaching naked-eye or binocular visibility
This is Ephemeris for Monday, December 6th. Today the Sun will be up for 8 hours and 56 minutes, setting at 5:02, and it will rise tomorrow at 8:06. The Moon, 2 days past new, will set at 7:27 this evening.
Comet 2021 A1, is also known as Comet Leonard, for its discoverer Gregory J. Leonard of the Mount Lemmon Survey, near Tuscon, Arizona. When it was found, on January 3rd this year, it was farther from the Sun than Jupiter. January 3rd of next year, less than a month from now, it will pass its closest to the Sun at a distance of around 57 million miles from the Sun. This is after falling in toward the Sun for the last 40,000 years. It will pass close to Venus, and its orbit will be tweaked to escape the solar system to eventually head out among the stars. Tomorrow morning it will be 7 ½ degrees or 3 fingers below left of Arcturus, the brightest star in the east before 6:30. It’s 5th magnitude, but still requires binoculars for most folks to be able to spot.
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
Comet Leonard (C/2021 A1) finder chart for 6:30 am, December 7, 2021. The comet’s tail may not be visible visually. The comet’s head, what astronomers call a coma, may appear as a large fuzzy spot. At that time it will be 29 million miles away, and will come within 22 million miles at its closest to us on the 12th. Created using Stellarium.
Comet Leonard’s positions at 6:30 am on the dates indicated. The labels are Month-Day Total Magnitude. The star’s position relative to the horizon and the position of Mars are for November 27th. The star field will be shifting to the upper right each morning at 6:30 from the November 27th date at 6:30. Comets always appear dimmer than their magnitude suggests because they are extended objects, not points like stars. Also, comet magnitudes can be unpredictable. The comet tails shown show the direction of the tail, if visible, only. Created using Cartes du Ciel (Sky Charts). I’ve reversed the colors from previous printings of this image. Reprinted from my article in the Stellar Sentinel, the newsletter for the Grand Traverse Astronomical Society.
11/29/2021 – Ephemeris – Orion is rising in the evening sky
This is Bob Moler with Ephemeris for Monday, November 29th. Today the Sun will be up for 9 hours and 6 minutes, setting at 5:04, and it will rise tomorrow at 7:59. The Moon, 2 days past last quarter, will rise at 3:07 tomorrow morning.
In the east, the central winter constellation Orion the hunter throws a leg over the horizon between 8 and 9 p.m. as Robert Frost told in his poem Star-Splitter. The upright rectangle that is his body on December evenings is tilted to the left as he rises, with a bright red star Betelgeuse at the top left of the rectangle, his shoulder. At the opposite corner is blue-white Rigel, a knee. In the center of the rectangle is a line of three stars nearly vertically aligned as he rises, which represents Orion’s belt. The Anishinaabe native peoples of this area call him the Wintermaker. His rising in the evening heralds the coming of winter.
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 stars of Orion and Wintermaker rising in this 4-step animation: Stars only, Western constellation lines and bright star names, Western constellation figure, Ojibwe (Anishinaabe) constellation figure. Created using Stellarium and GIMP.
11/24/2021 – Ephemeris – Let’s search for the naked-eye planets for this week
This is Ephemeris for Wednesday, November 24th. Today the Sun will be up for 9 hours and 15 minutes, setting at 5:07, and it will rise tomorrow at 7:53. The Moon, 3 days before last quarter, will rise at 9:19 this evening.
Let’s search for the naked-eye planets for this week. Venus will be visible in the southwestern evening twilight by 5:30 tonight. It’s a fat crescent in telescopes. Venus will set at 7:49 pm. By 5:45 pm, both Jupiter and Saturn should be able to be spotted in the southern sky. Saturn will be dimmer, and to its right. It will set first at 9:54 pm, with Jupiter following at 11:19 pm. Saturn’s rings are a beautiful sight in a telescope of even modest power, but the planet will appear tiny. Jupiter, however, is still quite large, in binoculars it might seem that it only has two moons tonight, since Io and Europa are together on one side, and Ganymede and Callisto are together on the other side.
The astronomical event times given above and below are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.
Addendum
The evening planets Venus, Saturn and Jupiter at 5:45 pm this evening, November 24, 2021. Created using Stellarium.
The Moon as it might appear in binoculars or small telescope, tomorrow morning, November 25, 2021. Created using Stellarium.
Telescopic views of the bright planets (north up) as they would be seen in a small telescope, with the same magnification, this evening at 7 pm, November 24, 2021. Apparent diameters: Venus, 35.32″, 33.4% illuminated; Saturn 16.15″, its rings 37.61″; Jupiter, 39.07″. The ” symbol means seconds of arc (1/3600th of a degree.) Click on the image to enlarge it. Created using Cartes du Ciel (Sky Charts).
The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on November 24, 2021. The night ends on the left with sunrise on the 25th. Click on the image to enlarge it. Created using my LookingUp program.
11/18/2021 – Ephemeris – An almost total eclipse of the Moon will be visible early tomorrow morning
This is Ephemeris for Thursday, November 18th. Today the Sun will be up for 9 hours and 27 minutes, setting at 5:11, and it will rise tomorrow at 7:45. The Moon, 1 day before full, will set at 7:58 tomorrow morning.
Should our normal November clouds depart in the early morning hours tomorrow, we will be treated with a very deep partial eclipse of the Moon. At 4:03 am, the Moon will be 97% immersed into the Earth’s inner shadow, with lower left edge peeking out into sunlight. I haven’t heard of any massive volcanic eruptions in our Southern Hemisphere, so the light leaking and bent though the Earth’s atmosphere from all the simultaneous sunrises and sunsets during the eclipse won’t be too diminished and give us a coppery hue in the shadow. The shadow will touch the Moon at its top edge at 2:19 am. The maximum will occur at 4:03 am, and the last bit of the shadow will depart at the lower right edge of the Moon at 5:47 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
November 19, 2021, partial lunar eclipse maximum at 4:05 am EST. Orientation of the Moon and shadow could be different if not viewing from Northern Michigan. Created using Stellarium.
Lunar Eclipse Diagram for November 19, 2021. Effects of the eclipse on the Moon at P1 and P4 are not visible. U1 is the Moon at the beginning of the partial eclipse. U4 is the Moon at the end of the partial eclipse. A duskiness on the Moon’s face on the side closest to the umbral shadow will be visible just before and after the partial eclipse. Note that this diagram is not at the same orientation that an observer might experience. Created from a NASA PDF document on the NASA Eclipse Website. https://eclipse.gsfc.nasa.gov/eclipse.html.
11/17/2021 – Ephemeris – Let’s search for the naked-eye planets for this week
This is Ephemeris for Wednesday, November 17th. Today the Sun will be up for 9 hours and 29 minutes, setting at 5:12, and it will rise tomorrow at 7:44. The Moon, 2 days before full, will set at 6:54 tomorrow morning.
Let’s search for the naked-eye planets for this week. Venus will be visible in the southwestern evening twilight by 5:30 tonight. It’s a fat crescent in telescopes. Venus will set at 7:48 pm. By 5:45 pm, both Jupiter and Saturn should be able to be spotted in the southern sky. Saturn will be dimmer, and to its right. It will set first at 10:19 pm, with Jupiter following at 11:42 pm. Saturn’s rings are a beautiful sight in a telescope of even modest power, but the planet will appear tiny. Jupiter, however, is still quite large, and its four biggest moons are spread out and might all be glimpsed in binoculars. In the morning sky, Mars is starting to make its appearance, rising at 6:33. Binoculars might be able to pick it out low in the east-southeast until 7:15 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
The evening planets Venus, Saturn and Jupiter at 5:45 pm this evening, November 17, 2021. Created using Stellarium.
The Moon in binoculars or small telescope as it might appear tonight, November 17, 2021. Created using Stellarium.
Mars in twilight, tomorrow morning at 7 am, November 18, 2021. Create using Stellarium.
Telescopic views of the bright planets (north up) as they would be seen in a small telescope, with the same magnification, this evening at 7 pm, November 17, 2021. Apparent diameters: Venus, 31.89″, 38.3% illuminated; Saturn 16.32″, its rings 38.01″; Jupiter, 39.95″. Mars in the morning is not shown, but is 3.70″ in diameter. The ” symbol means seconds of arc (1/3600th of a degree.) Click on the image to enlarge it. Created using Cartes du Ciel (Sky Charts).
In the image above, Jupiter’s moon Europa is shown. Actually, before 7:03 pm, it will be hidden in Jupiter’s shadow. Watching it appear is kind of cool. Eclipses of Jupiter’s moons happen all the time. The information for the satellite events is published in Sky and Telescope Magazine. Also tonight, farther to the west, farther out than Ganymede, is the star 45 Capricorni, about the same brightness as the Jovian moons, and nearly in line with them. Don’t mistake it for one of the moons, especially before Europa appears.
The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on November 17, 2021. The night ends on the left with sunrise on the 18th. Click on the image to enlarge it. Created using my LookingUp program.
11/12/2021 – Ephemeris – The Moon appears to wobble slowly over the month
This is Ephemeris for Friday, November 12th. Today the Sun will be up for 9 hours and 41 minutes, setting at 5:17, and it will rise tomorrow at 7:37. The Moon, 1 day past first quarter, will set at 1:27 tomorrow morning.
When I look at the Moon, I check the position of one particular feature. A small, nearly circular gray area near the right or western edge of the Moon’s disk. It’s called the Sea of Crises, or in Latin, Mare Crisium. The reason I check it is that over the month its distance from the edge, or what astronomers call the limb, changes. That sea is about as far as it can get from the limb now. The reason for this wobbling back and forth, called libration, is that the Moon rotates at a constant rate due to angular momentum, but its revolution around the earth is an ellipse, so it doesn’t move with a uniform speed in its orbit. It moves faster at its closest to the Earth, called perigee, and is slowest at apogee, its farthest from the Earth.
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 Moon tonight (November 12, 2021) showing Mare Crisium (Sea of Crises) about as far from the limb (Moon’s edge) as it can get. Created using Stellarium.
Simulation of the Moon’s phase and libration for October 2007 by Tomruen. Image is in the Public Domain.
11/11/2021 – Ephemeris – The Moon passes Jupiter and a minor meteor shower tonight.
This is Bob Moler with Ephemeris for Veterans Day, Thursday, November 11th. Today the Sun will be up for 9 hours and 43 minutes, setting at 5:18, and it will rise tomorrow at 7:36. The Moon, at first quarter today, will set at 12:16 tomorrow morning.
By tonight, the Moon will have moved over and just passed Jupiter. The bright planet will be to the right and above the first quarter Moon. There is also a meteor shower occurring, well actually two. They are minor, with maybe 5 to 15 meteors per hour at peak. With both showers, the radiants, that is where the meteors seem to come from, is in Taurus the Bull near the Pleiades star cluster. The notes I have for the Northern Taurids is that they are slow and bright, not bothered by a bright Moon. So if a meteor is spotted in the evening coming from the east, it’s probably a North Taurid meteor. As the night progresses the radiant will move westward, higher in the sky and begin to set in the west as morning twilight starts.
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
Viewing the Moon’s passage by Saturn and Jupiter for three nights, November 9, 10 and 11 2021. Note that while the Moon is jumping eastward, to the left, the planets and stars are moving the other way, but much more slowly. The Moon moves 360° around the sky in about 29 1/2 days, so it moves about 12° or 24 of its diameters every day. The movement of the stars and planets in the other direction is because we are staying at the same solar time, 7 pm. However, the Earth is orbiting the Sun at a little less than a degree a solar day. To keep the stars stationary, our daily interval should be one sidereal day, the time it takes the earth to rotate with respect to the stars, which is 23 hours 3 minutes and 56 seconds. Should we have stepped at the sidereal rate, the very slight eastward motion of these outer planets may have been noticeable. Created using Stellarium, and GIMP.
North and South Taurid radiants seen in the east at 9 pm on November 11th. The Northern Taurid radiant is the most active now. Note the Pleiades just to the upper left of the Northern Taurid radiant. The face of Taurus the bull is below as a sideways V where Taurus is displayed. However, since the meteors are seen all over the sky, it might be difficult to trace them back to a specific radiant. Created using Stellarium.
As a side note, about the face of Taurus. The stars, except the brightest one, Aldebaran, belong to a star cluster called the Hyades. They are, mythologically, the half-sisters of the Pleiades. Also, the V can be an upside down A. I am currently working on a program I’m going to present at the December Zoom meeting of the Grand Traverse Astronomical Society about astronomy in ancient times. Back when the alphabet was developed in the Middle East 4000-4500 years ago, Taurus, not Aries was the first sign of the zodiac, so apparently the first letter of the alphabet “Aleph” was modeled after the face of Taurus.
Other tidbits are: the reason there are 24 hours in a day, and 60 minutes in an hour. There are lots of others. We can handle up to 100 people joining the meeting. It’s at 8 pm EST (UT – 5 hours), December 3rd [01:00 UT, December 4th]. To join the meeting, go to www.gtastro.org for instructions and a link.
11/09/2021 – Ephemeris – The Moon, Saturn and the return to standard time
This is Bob Moler with Ephemeris for Tuesday, November 9th. Today the Sun will be up for 9 hours and 48 minutes, setting at 5:20, and it will rise tomorrow at 7:33. The Moon, 2 days before first quarter, will set at 9:48 this evening.
Ever since new moon, the Moon has been moving eastward each night. It will be approaching Saturn tonight, and pass south or below Saturn at mid-morning tomorrow. By tomorrow night, the Moon will have moved just past Saturn, on its way toward Jupiter. The return to standard time since Sunday has darkened our evenings and lightened our mornings. We are about 30 days from the earliest sunset on December 9th, just 18 minute earlier than tonight’s sunset. Our sunrise has a longer time to go to reach last week’s late sunrise times, all the way to January second. Thanks to Congress’s messing around with it, we are on daylight saving time for a longer part of the year than standard time. Don’t get me started.
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
Viewing the Moon’s passage by Saturn and Jupiter for three nights, November 9, 10 and 11, 2021. Created using Stellarium, and GIMP.
11/04/2021 – Ephemeris – Myths of the Pleiades from some other cultures
This is Ephemeris for Thursday, November 4th. The Sun will rise at 8:25. It’ll be up for 10 hours and 1 minute, setting at 6:26. The Moon is new today, and won’t be visible.
Let’s look at how some other cultures saw the Pleiades, the star cluster that is seen in the eastern sky these evenings. To the Anishinaabe native peoples around here, the Pleiades is the “Hole in the Sky” or the seven stones that are heated for the sweat lodge ceremony. To the Kiowa, these were sister stars that had been whisked into the sky from the top of Devil’s Tower in Wyoming, where they were threatened by a huge bear. In Norse mythology, these were the goddess Freya’s hens. The name we know them by has rather misty origins. Some think the Greek name is from the mother of the seven sisters, Pleione. The Greek word for sail is similar to Pleiades, and it seems the appearance of the Pleiades in the morning sky saw the best sailing weather in the Mediterranean.
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
Finding the Pleiades animation for 9 p.m. October 29, 2019. Created using Stellarium and GIMP.
Seven maidens being attacked by a giant bear, having fled to the top of Devil’s Tower in Wyoming. Painting by Herbert Collins, http://www.nps.gov/deto.
They are also the Seven Daughters of the Moon and Sun. They loved to dance and play, and when their father, the Moon was low in the sky, would descend to the Earth in a basket to do their thing. On one of their trips to the earth, one of them was captured by a human, and she ended up falling in love with him, and married him. When father Moon found out he permanently dimmed her star, so now most people now only can spot 6 of the stars. This last bit seems to parallel the Greek story of the lost Pleiad.
11/03/2021 – Ephemeris – Searching for the naked-eye planets for this week
This is Ephemeris for Wednesday, November 3rd. The Sun will rise at 8:23. It’ll be up for 10 hours and 4 minutes, setting at 6:28. The Moon, 1 day before new, will rise at 7:56 tomorrow morning.
Let’s search for the naked-eye planets for this week. Venus should be visible in the southwestern evening twilight by 6:50 tonight. It’s a fat crescent in telescopes. Venus will set at 8:44 pm. By 7 pm, Jupiter should be able to be spotted in the south-southeastern sky. Saturn will be dimmer, and to its right. They will set after midnight in the southwest, with Saturn setting first at 12:11 am, and Jupiter following at 1:32. Saturn’s rings are a beautiful sight in a telescope of even modest power, but the planet will appear tiny. In the morning sky, Mercury will be harder to spot than it was last week. It will be visible and low in the east-southeast from 7:30 to 8 am. All four of Jupiter’s brightest moons will be visible in binoculars early in the evening tonight.
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
Venus will appear low in the south-southwest by 6:50 pm tonight, November 3, 2021. Created using Stellarium.
Venus, Jupiter and Saturn at 7 pm in the southern sky. Created using Stellarium.
Mercury in morning twilight at 7:45 am, November 4, 2021. Created using Stellarium.
Telescopic views of the bright planets (north up) as they would be seen in a small telescope, with the same magnification, this evening at 9 pm, November 3, 2021. Apparent diameters: Venus at 7 pm, 26.54″, 46.7% illuminated; Saturn 16.69″, its rings 38.88″; Jupiter, 41.77″. Mercury at 7:30 am on the 4th and not plotted, 5.49″, 86.4% illuminated. The Jovian moon Io will begin transiting the face of the planet at 11:14 pm. Its shadow will start to cross at 12:32 am. The ” symbol means seconds of arc (1/3600th of a degree.) Click on the image to enlarge it. Created using Cartes du Ciel (Sky Charts).
The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on November 3, 2021. The night ends on the left with sunrise on the 4th. Click on the image to enlarge it. Created using my LookingUp program.
