05/20/2021 – Ephemeris – Our first look at next Wednesday’s lunar eclipse

May 20, 2021 Comments off

This is Bob Moler with Ephemeris for Thursday, May 20th. Today the Sun will be up for 15 hours and 1 minute, setting at 9:10, and it will rise tomorrow at 6:08. The Moon, 1 day past first quarter, will set at 3:51 tomorrow morning.

Next Wednesday’s lunar eclipse will be total as seen from half the Earth’s surface, but not the half we’re on. We will catch the start of the eclipse as the Moon is setting, and the Sun is rising. That puts us in a unique position. For 5 minutes between sunrise and moonset we will be able to see both the Sun and the Earth’s shadow falling on the Moon. The Earth’s atmosphere bends the Sun’s red rays into the Earth’s shadow, which is why the Moon usually appears red when totally eclipsed and not completely black. The Sun’s light rays that pass over our heads will continue through our atmosphere to be bent more and will pass into the Earth’s shadow so someone farther west of us can enjoy the red totally eclipsed Moon.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

This is a diagram of the Moon’s passage through the Earth’s shadow. P1 is the contact with the edge of the Moon entering the Earth’s penumbra shadow, an event that cannot be seen. U1 is the first contact with the Earth’s inner umbra shadow and the start of the partial eclipse. U2 is the second contact with the edge of the umbra and the start of totality. U3 is the third contact with the umbra and the end of totality and the beginning of the ending partial phase. U4 is the end of the partial phase, with the Moon now back in the penumbra. P4 is when the Moon leaves the penumbra. Click on the image to enlarge. Credit: NASA/GSFC/Fred Espenak.
Visibility map for the May 26, 2021. The events U1-4 and P1&4 are contacts with the Earth’s shadow. Click on the image to enlarge. Credit: NASA/GSFC/Fred Espenak.

The two charts above are contained in a single PDF here-> https://eclipse.gsfc.nasa.gov/LEplot/LEplot2001/LE2021May26T.pdf.

UT (Universal Time) to EDT conversion: Subtract 4 hours.

05/19/2021 – Ephemeris – Let’s search for the naked-eye planets for this week

May 19, 2021 Comments off

This is Bob Moler with Ephemeris for Wednesday, May 19th. Today the Sun will be up for 14 hours and 59 minutes, setting at 9:09, and it will rise tomorrow at 6:09. The Moon, at first quarter today, will set at 3:26 tomorrow morning.

Let’s search for the naked-eye planets for this week. Mars will be joined by two more planets seen in twilight. Both Mercury and Venus are now just above where the Sun set. By 10 pm Mercury should be able to be spotted low in the west-northwest. Venus might be spotted lower and somewhat earlier, it’s a lot brighter than Mercury. Venus will be setting at 10:21 pm with Mercury following at 11:04. Mars can be found in the west at 10:30 tonight, in the constellation of Gemini the twins. Tonight it’s in the middle of the constellation. Mars will set at 12:42 am. Jupiter and Saturn, are in the morning sky. Saturn will rise at 2:03 am, with brighter Jupiter rising at 2:43 am. By 5 am they will be in the southeast in the morning twilight.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Venus and Mercury in twilight
Mercury and Venus as they might appear at 10 pm tonight over a low Lake Michigan horizon. Mercury will be that hard to spot. Binoculars will help. Mercury is getting dimmer as its phase becomes an increasingly thinner crescent. Venus here is only 3 degrees above the Horizon. For other locations, this is 51 minutes after sunset. Created using Stellarium.
Mars finder animation
Mars finder animation for 11 pm tonight, May 19, 2021. Mars is no longer a first magnitude star-like object, having dropped to second magnitude. Created using Stellarium and GIMP.
Telescopic Moon
The Moon as it might appear in a telescope tonight at 11 pm May 19, 2021 (03:00 UT 05/20/2021 for folks not in the US Eastern Daylight Time Zone). Two of my favorite craters (Tycho and Clavius) are on the terminator tonight. Created using Stellarium.
Jupiter and Saturn in the morning
Jupiter and Saturn as they might appear at 5 am tomorrow morning. Created using Stellarium.
Telescopic planets
Saturn and Jupiter as seen in a small telescope at the same magnification. Apparent diameters: Saturn, 17.28″, rings, 40.24″; Jupiter, 39.81″. Mars is too far away to make out detail on its surface, except maybe a polar cap. Its apparent diameter is 4.30″. Venus’ apparent diameter is 10.00″ and will be added when it gets far enough from the Sun to be easily seen. Mercury’s apparent diameter is 8.88″. The normal cutoff for whether to show a planet here is an apparent diameter of 10″ or greater. The ” symbol means seconds of arc (1/3600th of a degree). Created using Cartes du Ciel (Sky Charts).
Planets and Moon at sunrise and sunset
Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on May 19, 2021. The night ends on the left with sunrise on the 20th. Click on the image to enlarge. Created using my LookingUp program.

05/18/2021 – Ephemeris – Eclipses visible in Northern Michigan this year

May 18, 2021 Comments off

This is Ephemeris for Tuesday, May 18th. Today the Sun will be up for 14 hours and 56 minutes, setting at 9:08, and it will rise tomorrow at 6:10. The Moon, 1 day before first quarter, will set at 2:57 tomorrow morning.

This year we will see in part or in full three eclipses from our Northern Michigan location. The first will be the start of a total lunar eclipse next week Wednesday, May 26th. It will start just before sunrise, which for a full moon is around moonset. Our next eclipse will be a solar eclipse that starts, for us, before sunrise on June 10th. In fact, most of the eclipse will occur before sunrise for us in Northern Michigan. The farther north and east of us the more of the eclipse you’ll see. I’ll have more information on the lunar in the next week of programs. And the solar eclipse as we approach that date. We have a final lunar eclipse this year. That will occur in the wee morning hours of November 19th, a partial, but almost total eclipse.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The four eclipses that occur in 2021

We in Northern Michigan we’ll see part of the first two and all of the third.

May 26, 2021 Total Lunar Eclipse
The visibility map for the May 26th total lunar eclipse. Note Michigan’s mitten lies between the U1 and U2, which means that the Moon will set after the partial eclipse starts, but before totality. Credit: NASA/GSFC/Fred Espenak

June 10, 2021 Annular Solar Eclipse

The visibility map for the June 10, 2021 annular solar eclipse. In an annular eclipse the Moon is too far away and appears too small to cover the face of the Sun. So, at maximum a ring of bright Sun surrounds the Moon. It’s sometimes called a ring of fire. For locations within the big floppy figure 8 the eclipse either ends near sunrise or starts near sunset. The double red line with the ellipses in it is the path of where the ring is visible. Locations within the blue grid will see a partial eclipse. Credit: NASA/GSFC/Fred Espenak.
November 19, 2021 Partial Lunar Eclipse
The visibility map for the November 19, 2021 partial eclipse. The eclipse is visible in its entirety in the morning of the 19th. This eclipse is almost total. Credit: NASA/GSFC/Fred Espenak.
December 4, 2021 Total Solar Eclipse
Visibility map for the December 4, 2021 total solar eclipse. Totality is onlt visible from the Southern Ocean and Antarctica, Credit: NASA/GSFC/Fred Espenak.

05/17/2021 – Ephemeris – The Moon tonight

May 17, 2021 Comments off

This is Ephemeris for Monday, May 17th. Today the Sun will be up for 14 hours and 54 minutes, setting at 9:06, and it will rise tomorrow at 6:11. The Moon, 2 days before first quarter, will set at 2:25 tomorrow morning.

The Moon tonight reveals a bit more territory than it did last night, and will every night until full moon. The Moon’s solar day equals a lunar month of about 29 and a half of our days. As seen in binoculars, below and left of The distinctly oval Sea of Crises, or Mare Crisium, is the Sea of Fertility, or Mare Fecunditatis. To the left of the Sea of Crises, the Sea of Tranquility (Tranquilitatis) where the Apollo 11 crew landed. Above that half of Sea of Serenity has come into daylight. Tonight the Beehive star cluster will be visible below and left of the Moon. It should be easily visible in binoculars and has a vaguely triangular shape. It was known to the ancients as Praesepe, the manger, who saw it as a glowing spot on moonless nights.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The crescent Moon and the Beehive star cluster
The crescent Moon and the Beehive star cluster, below left of center as they might be seen in binoculars tonight, May 17, 2021 at 10 pm. The Beehive is also known as Messier 44 or M 44. The star cluster is visible to the naked eye, but it stars are not resolvable, so it looks like a small glowing patch. It was known as Praesepe, the manger. The star just left of the Moon and another just left of the Beehive are Asellus Borealis and Asellus Australis respectively, the North and South Donkeys. They are feeding at the manger. The donkey stars and the Beehive are in the central part of the constellation of Cancer the crab. The image was created using Stellarium.
The Moon a10 pm May 17, 2021 as seen in a low power telescope with the lunar seas labeled in English, rather than Latin. The seas are easily visible in binoculars. Created using Stellarium and GIMP.

05/14/2021 – Ephemeris – Astronomy Day Star Party this Saturday

May 14, 2021 Comments off

This is Bob Moler with Ephemeris for Friday, May 14th. Today the Sun will be up for 14 hours and 48 minutes, setting at 9:03, and it will rise tomorrow at 6:14. The Moon, 3 days past new, will set at 12:07 tomorrow morning.

Tomorrow is International Astronomy Day, to celebrate it the Sleeping Bear Dunes National Lakeshore and Grand Traverse Astronomical Society will hold a special virtual star party via the Zoom Internet app. If it’s clear, Northwestern Michigan College’s professor Jerry Dobek will be transmitting live images of celestial objects that will look pretty much like what one sees through the eyepiece of a telescope. Dr. Dobek will be using the Joseph H. Rogers 0.4 meter main telescope and commenting will be members of the Grand Traverse Astronomical Society. Featured objects will be the 4-day-old crescent Moon, the tiny and elusive planet Mercury, star clusters and galaxies. The event starts at 9 pm though best viewing won’t begin until after about 9:30. Go to www.gtastro.org for instructions and a link.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

While attending the virtual star party you can capture the screen imaged with Alt/Print Screen keys. Paste the image into a paint or other program. I use GIMP (Gnu Image Manipulation Program), which fits my budget… It’s free. You can save the image of play with it. What I do with it is to darken the background. It should be black.

This is globular star cluster M 3. I call it the first globular cluster of spring. It’s near the star Arcturus. This is a screen capture cropped. The capture device on the 0.4 meter telescope is the Revolution Imager R2, which is actually fairly inexpensive. It outputs a video image.

I paste this image into GIMP. I use the Levels control under the Color tab.

I move the left control under the histogram to darken the sky. The left control here is set to 119, so all brightness values less than a brightness of 119 is set to black. Click OK and export the image. I didn’t change anything else.
Resultant image. Not bad. Though, I find globular clusters look better visually than their images. That is not true of nebulae or galaxies.

05/13/2021 – Ephemeris – The Moon and Mercury will appear near one another tonight

May 13, 2021 Comments off

This is Ephemeris for Thursday, May 13th. Today the Sun will be up for 14 hours and 45 minutes, setting at 9:02, and it will rise tomorrow at 6:15. The Moon, 2 days past new, will set at 11:08 this evening.

Tonight starting around 9:30, or half an hour after sunset is a good time to spot the thin crescent two day old Moon and the planet Mercury. The tiny and elusive Mercury will be about 7 moon widths to right of the Moon. With the Moon near Mercury, it should be easier to find instead of trying to locate it in the great expanse of featureless twilit sky. Mercury has a weird rotational period. In my youth astronomers thought that Mercury rotated so that one face would perpetually face the Sun, So it would rotate in the same time it orbits the Sun of 88 days. That’s what happens when the Moon orbits the Earth. However, Mercury rotates in exactly 2/3rds of its orbital time, making its solar day two of its years long or 176 Earth days.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Closeup of the Moon exhibiting earth shine and Mercury at 9:30 pm tonight May 13, 2021. Created using Stellarium.
Mercury rotates on its axis in 59 earth-days with respect to the stars. That’s called the sidereal rotation. As you can see, by following the rotating arrow, its rotation with respect with the Sun is two of its years or 176 earth-days. Earth’s sidereal rotation is 23 hours 56 minutes and 4 seconds. Our rotation with respect to the Sun averages 24 hours exactly. This work has been released into the public domain by its author, Age234 at the Wikipedia project.
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05/12/2021 – Ephemeris – Searching for the naked-eye planets for this week

May 12, 2021 Comments off

This is Ephemeris for Wednesday, May 12th. Today the Sun will be up for 14 hours and 43 minutes, setting at 9:01, and it will rise tomorrow at 6:16. The Moon, 1 day past new, will set at 10:06 this evening.

Let’s search for the naked-eye planets for this week. Mars will be joined by two more planets seen in twilight. Both Mercury and Venus are now just above where the Sun set. By 9:30 pm Mercury should be able to be spotted low in the west-northwest. Venus might be spotted lower and somewhat earlier. Venus will be setting at 10:02 pm with Mercury following at 11 pm. Mars can be found in the west at 10 pm tonight, in the constellation of Gemini the twins. Tonight it’s in the middle of the constellation. Mars will set at 1:02 am. Jupiter and Saturn, are in the morning sky. Saturn will rise at 2:30 am, with brighter Jupiter rising at 3:13 am. By 5:30 am they will be low in the southeast in the morning twilight.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Mercury and Venus low in the west-northwest tonight at 9:30 pm or a half hour after sunset. The one-day-old Moon appears just to the left of Venus. Mercury will be 14 degrees above the Lake Michigan horizon, and Venus only 5 degrees. By tomorrow night, the Moon will be to the left of Mercury. Created using Stellarium.
Mars finder animation for 10:30 pm tonight or about an hour and a half after sunset. Bonus: Mercury is still up. Created using Stellarium and GIMP.
Jupiter and Saturn in morning twilight tomorrow morning May 23, 2021. Created using Stellarium.
Saturn and Jupiter as seen in a small telescope at the same magnification. Apparent diameters: Saturn, 17.05″, rings, 39.71″; Jupiter, 38.83″. Mars is too far away to make out detail on its surface, except maybe a polar cap. Its apparent diameter is 4.43″. Venus’ apparent diameter is 9.97″ and will be added when it gets far enough from the Sun to be easily seen. Mercury’s apparent diameter is 7.29″. The cutoff for whether to show a planet here is an apparent diameter of 10″ or greater. The ” symbol means seconds of arc (1/3600th of a degree). Created using Cartes du Ciel (Sky Charts).
Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on May 12, 2021. The night ends on the left with sunrise on the 13th. Click on the image to enlarge. Created using my LookingUp program.

05/11/2021 – Ephemeris – The Big Dipper as seen by many peoples

May 11, 2021 Comments off

This is Ephemeris for Tuesday, May 11th. Today the Sun will be up for 14 hours and 41 minutes, setting at 9 pm, and it will rise tomorrow at 6:17 am. The Moon is new today, and won’t be visible.

The Big Dipper is overhead, actually north of overhead this evening when it gets dark for us in Michigan, it’s seven stars shining brightly. The Big Dipper is not an actual constellation, recognized internationally. It’s part, the hind part, of Ursa Major, the great bear. The Big Dipper is an asterism or informal constellation. It is a distinctly North American constellation. For fugitive slaves, fleeing the southern states in the days before the Civil War, the Drinking Gourd, as they called it, showed the direction north to freedom. In England the dipper stars become the Plough (plow), or Charles’ Wain (Charlemagne’s Wagon). In France, known for culinary delights it was the saucepan, or the cleaver. Many cultures saw what was familiar to them in these seven bright stars.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Big Dipper as seen by different cultures
Cultural views of the Big Dipper as an Animation: Big Dipper/Sauce Pan, Plough (plow), Charle’s Wain (Charlemagne’s wagon), and Cleaver.

05/10/2021 – Ephemeris – The story of the constellations Boötes and Ursa Major

May 10, 2021 Comments off

This is Bob Moler with Ephemeris for Monday, May 10th. Today the Sun will be up for 14 hours and 38 minutes, setting at 8:58, and it will rise tomorrow at 6:18. The Moon, 1 day before new, will rise at 6:25 tomorrow morning.

Seen in the east at 10 p.m. tonight is the kite shaped constellation of Boötes the herdsman. The bright star Arcturus is at the bottom of the kite to the right. It is pointed to by the arc of the handle of the Big Dipper, higher in the east. Boötes represents a young hunter named Arcas, son of Callisto, a beautiful young lady who had the misfortune of being loved by Zeus the chief of the Greek gods. Zeus’ wife Hera, found out about it, and since she couldn’t punish Zeus, turned the poor woman into a bear. Arcas, many years later, unaware of the events surrounding his mother’s disappearance was about to kill the bear when Zeus intervened and placed them both in the sky to save her, as Arcas still pursues her across the sky nightly.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Arcas and Callisto as Boötes and Ursa Major
Bootes and Ursa Major aka Arcas chasing Callisto around the pole of the sky. Created using Stellarium.
Arcas and Callisto woodcut
Arcas about to slay the bear by the 17th century artist Baur. Source: University of Virginia Electronic Text Center

05/06/2021 – Ephemeris – Corvus, Crater, Hydra and Apollo

May 6, 2021 Comments off

This is Ephemeris for Thursday, May 6th. Today the Sun will be up for 14 hours and 28 minutes, setting at 8:54, and it will rise tomorrow at 6:24. The Moon, 3 days past last quarter, will rise at 5:04 tomorrow morning.

The small constellation of Corvus the crow is located low in the south at 10:30 this evening. It’s made of 5 dim stars, but the pattern is a distinctive but distorted box with two stars at the upper left marking that corner. To the right is a fainter constellation of a thick stemmed goblet called Crater. Both appear above the long constellation of Hydra the water snake who is slithering just above the southern horizon. In Greek mythology Corvus, then white, was the god Apollo’s pet. Apollo once bid Corvus to take a cup and fetch him some water. Corvus however dallied and waited for a green fig to ripen. He grabbed a snake and returned with a story as to how the snake had delayed him. The angry Apollo turned the crow and all crows to this day black.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Corvus-Crater-Hydra finder animation
Corvus-Crater-Hydra finder animation for 10:30 pm May 6. Click on the image to enlarge. Created using Stellarium and GIMP.