05/31/2021 – Ephemeris – Hercules the constellation

This is Bob Moler with Ephemeris for Memorial Day, Monday, May 31st. Today the Sun will be up for 15 hours and 19 minutes, setting at 9:20, and it will rise tomorrow at 6:00. The Moon, 2 days before last quarter, will rise at 2:23 tomorrow morning.

Orion, the hard luck mythological Greek hunter gets a splashy constellation in the winter sky, but the greatest hero of all, Hercules, gets a dim group of stars on the border between the spring and summer stars. At 11 p.m. Hercules is fairly high in the east. It is located above and a bit right of the bright star, Vega east-northeast. Hercules’ central feature is a keystone shaped box of stars, called the Keystone laying on its side, which represents the old boy’s shorts. From each left corner stars extend lines of stars that are his legs, from the right stars, the rest of his torso and arms extend. So in one final indignity he’s upside down in our sky. For those with a telescope, Hercules contains the beautiful globular star cluster Messier 13.

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

Addendum

Hercules can be found in the east among the line of constellations at around 11 pm in late May or early June between the bright stars Arcturus and Vega. Created using Stellarium and GIMP.

M 13 is found on the western side of the Keystone. In this orientation when Hercules is in the east, it is the top side. Created using Stellarium with an annotation.

M 13, the Great Globular Star Cluster in Hercules. Credit: Scott Anttila.

M 13 is the brightest and finest globular star cluster in the northern hemisphere of the sky. It’s at a distance of 25 thousand light years. Some amateur astronomers can spot M 13 with the naked eye. It is a fuzzy spot in binoculars. I can barely resolve some of its stars in an 8-inch (200 mm) telescope. It’s a wonderful sight in anything bigger! The slightly dimmer M 92 is also slightly farther away at nearly 27 thousand light years. 

Click on any of the images above to enlarge them.

 

05/28/2021 – Ephemeris – The Northern Crown

This is Bob Moler with Ephemeris for Friday, May 28th. Today the Sun will be up for 15 hours and 15 minutes, setting at 9:18, and it will rise tomorrow at 6:01. The Moon, 2 days past full, will rise at 12:19 tomorrow morning.

High in the east-southeast at 11 this evening can be seen a small nearly circular constellation of Corona Borealis, the Northern Crown. It is just below Boötes, the kite shaped constellation off the handle of the Big Dipper. According to Greek myth the crown was given by the gods to the princess Ariadne, daughter of King Minos of Crete. The crown is more like a tiara with the bright star Alphecca at the front. To the Anishinaabe people, who are natives of our region, it is the Sweat Lodge. Part of what we call Hercules next to it is the Exhausted Bather, who is lying on the ground after the ceremony. The seven stones that are heated for the Sweat Lodge are the Pleiades, now too close to the Sun to be seen.

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

Addendum

Animated Corona Borealis Finder Chart looking to the east-southeast at 11 p.m. Created using Stellarium and GIMP.

05/27/2021 – Ephemeris – Miss yesterday’s eclipse? There’s 2 more in the next 12 months.

This is Bob Moler with Ephemeris for Thursday, May 27th. Today the Sun will be up for 15 hours and 13 minutes, setting at 9:17, and it will rise tomorrow at 6:02. The Moon, 1 day past full, will rise at 11:14 this evening.

While yesterday morning’s lunar eclipse may have been disappointing by setting just as it got going. That won’t happen with the next one. The next lunar eclipse visible from Northern Michigan will occur this November 19th, a Friday. It’s another morning eclipse, but doesn’t compete with sunrise or morning twilight. It’s not quite total, but nearly 97.5% of the Moon’s diameter will be covered by the Earth’s inner umbral shadow. The partial eclipse will start at 2:18 am and end at 5:47 am, which in November is nowhere near sunrise. We seem to be coming into a fortuitous period of eclipses in the next few years. Our next lunar eclipse after November will be next May 15th’s lunar eclipse, and it will be total and will conveniently happen in the evening.

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

05/26/2021 – Ephemeris – Let’s search for the naked-eye planets for this week

There is a lunar eclipse this morning. See https://bobmoler.wordpress.com/2021/05/25/05-25-2021-ephemeris-viewing-the-lunar-eclipse-tomorrow-morning/

This is Ephemeris for Wednesday, May 26th. Today the Sun will be up for 15 hours and 12 minutes, setting at 9:16, and it will rise tomorrow at 6:03. The Moon, at full today, will rise at 9:57 this evening.

Let’s search for the naked-eye planets for this week. Venus might be spotted low in the west-northwest twilight by 10 pm. Mercury will be a bit above and left of Venus, but is now too dim to spot. Venus will set at 10:36 pm. Mars can be found in the west at 10:30 tonight, in the constellation of Gemini the twins. Tonight it’s on the left side of the constellation, below Gemini’s brightest star, Pollux. Mars will set at 12:37 am. Jupiter and Saturn, are in the morning sky. Saturn will rise at 1:36 am. It’s seen with the stars of Capricornus. Brighter Jupiter, now within the boundaries of Aquarius, will rise at 2:21 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 where Mercury should be, see text, at 10 pm May 2, 2021. Created using Stellarium.

Mars at 11 pm May 26, 2021, seen below Pollux. Created using Stellarium.

The Moon as it might appear at 11 pm tonight. Shadows are starting to appear on the upper right edge of the Moon 17 hours after full moon. Created using Stellarium.

Jupiter and Saturn seen in the southern sky at 5 am, May 27, 2021. Created using Stellarium.

Saturn and Jupiter as seen in a small telescope at the same magnification at 5 am May 27, 2021. Apparent diameters: Saturn, 17.45″, rings, 40.64″; Jupiter, 40.58″. Mars is too far away to make out detail on its surface, except maybe a polar cap. Its apparent diameter is 4.22″. Venus’ apparent diameter is 10.21″ and will be added when it gets far enough from the Sun to be easily seen. Mercury’s apparent diameter is 10.20″. 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 the Moon at sunset and sunrise of a single night starting with sunset on the right on May 26, 2021. The night ends on the left with sunrise on the 27th. Click on the image to enlarge. Created using my LookingUp program.

05/25/2021 – Ephemeris – Viewing the lunar eclipse tomorrow morning

This post is for the appearance of the May 26th lunar eclipse in Michigan.

This is Ephemeris for Tuesday, May 25th. Today the Sun will be up for 15 hours and 10 minutes, setting at 9:15, and it will rise tomorrow at 6:04. The Moon, 1 day before full, will set at 6:09 tomorrow morning.

If we are really lucky tomorrow morning, and it is clear all the way down to the southwestern horizon at dawn we will witness the start of an eclipse of the Moon near sunrise and moonset. The eclipse starts at 4:48 am, but nothing unusual will be visible as the Moon starts to enter Earth’s outer, penumbral shadow. Perhaps by 5:15 the left edge of the Moon might appear dimmer than the right side. The Moon will be getting deeper in that shadow for the next half hour until at 5:45 it begins to enter the Earth’s inner shadow, the umbra. The only light in the umbra is that bent into it by the simultaneous sunrises and sunsets around the Earth. For the next 20 to 25 minutes the shadow will increase until the Sun rises and shortly after that the Moon sets around 6:09.

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

Addendum

Simulated image of the Moon deep in the penumbra of the lunar eclipse of May 26, 2021 at 5:40 am. Notice that the left side of the Moon is darker than the right side. I find that the effect is more noticeable when wearing sunglasses to cut down the Moon’s bright glare. Created using Stellarium.

Simulated view of the partially eclipsed Moon of May 26, 2021 setting on a flat horizon. Created using Stellarium and touched up by using GIMP.

Time	Event
4:47 am	Nautical twilight starts
4:48 am	The Moon enters penumbra (Nothing to see, the dimming on the left side is imperceptible)
5:15 am	The penumbral shadow should become visible at the left edge of the Moon by this time
5:45 am	The Moon enters the umbra (The partial part of the eclipse begins)
6:04 am	Sunrise for Traverse City
6:09 am	Moon sets for Traverse City

The sunrise and moon set times may vary by more than a few minutes depending on your location.

05/24/2021 – Ephemeris – Get ready for Wednesday morning’s lunar eclipse

This is Bob Moler with Ephemeris for Monday, May 24th. Today the Sun will be up for 15 hours and 8 minutes, setting at 9:14, and it will rise tomorrow at 6:04. The Moon, 2 days before full, will set at 5:33 tomorrow morning.

If we are really lucky Wednesday morning, and it is clear all the way down to the southwestern horizon at dawn, we will witness the start of an eclipse of the Moon as the Sun rises and the Moon sets. The first inkling that something strange is happening to the Moon will come around 5:15 am or so. The Moon will be deep in the Earth’s outer, partial, shadow called the penumbra and the left side of the Moon should appear darker than the rest of it. The brightening of the twilight should enhance the effect. The partial phase of the eclipse will start at 5:45, where the left edge of the Moon will actually begin to disappear into the Earth’s inner shadow, the umbra. Within 20 to 25minutes later the Sun will rise and shortly after the Moon will set.

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

Addendum

Simulated image of the Moon deep in the penumbra of the lunar eclipse of May 26, 2021 at 5:40 am. Notice that the left side of the Moon is darker than the right side. I find that the effect is more noticeable when wearing sunglasses to cut down the Moon’s bright glare. Created using Stellarium.

Simulated view of the partially eclipsed Moon of May 26, 2021 setting on a flat horizon. Created using Stellarium and touched up by using GIMP.

Time	Event
4:47 am	Nautical twilight starts
4:48 am	The Moon enters penumbra (Nothing to see, the dimming on the left side is imperceptible)
5:15 am	The penumbral shadow should become visible at the left edge of the Moon by this time
5:45 am	The Moon enters the umbra (The partial part of the eclipse begins)
6:04 am	Sunrise for Traverse City
6:09 am	Moon sets for Traverse City

The sunrise and moon set times may vary by more than a few minutes depending on your location.

05/21/2021 – Ephemeris – For everything there is a season… even eclipses

This is Ephemeris for Friday, May 21st. Today the Sun will be up for 15 hours and 3 minutes, setting at 9:11, and it will rise tomorrow at 6:07. The Moon, 2 days past first quarter, will set at 4:14 tomorrow morning.

There are seasons for everything: baseball season, football season, spring, summer, what have you. There are also eclipse seasons. The Moon’s orbit is tilted by about 5 degrees to the ecliptic, the path of the Sun in the sky. The points where they cross are called nodes, 180 degrees apart. When the Sun is near one of those nodes we are in an eclipse season, where a solar eclipse can occur at new moon, and a lunar eclipse can occur at full moon. We are guaranteed one of each per eclipse season, and on rare occasions a third eclipse. Of course one has to be at the right place to see an eclipse. This eclipse season we will be at a marginal place to see both eclipses. Both are at sunrise, so we’ll see just a part of each of them.

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

Addendum

A diagram of the paths of the Moon and Sun projected on the sky (celestial sphere). N1 and N2 are the nodes (crossing points). Nodes are ascending or descending depending on the northerly or southerly component of the Moon’s motion in crossing them. The Sun and Moon move in an easterly direction, but the Moon’s orbit precesses so that the line of nodes move in a westerly direction once around in 18.6 years. That’s why eclipse season intervals are 173.3 days and move backward in the calendar one year to the next. Eclipse seasons occur when the Sun is less than about 17.5 degrees from a node. Credit Earthsky.org.

For a more extensive treatment of this subject check out: https://earthsky.org/astronomy-essentials/definition-what-is-an-eclipse-season

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

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

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

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 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.

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 as they might appear at 5 am tomorrow morning. Created using Stellarium.

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 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

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.