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05/04/2021 – Ephemeris – We cross Halley’s Comet debris this week

May 4, 2021 Comments off

This is Bob Moler with Ephemeris for Tuesday, May 4th. Today the Sun will be up for 14 hours and 23 minutes, setting at 8:51, and it will rise tomorrow at 6:26. The Moon, 1 day past last quarter, will rise at 4:20 tomorrow morning.

The Eta Aquariid meteor shower will reach their peak for us Thursday morning the 6th. The Eta Aquariids are caused by bits of Halley’s Comet, passing the Earth’s orbit heading out from the Sun. The Orionids of late October are debris of Halley’s comet passing the Earth’s orbit heading in toward the Sun. The Eta Aquariids are named for the star nearest the radiant of the meteor shower. The constellation of Aquarius has many shower radiants, which is why the shower is named for a star in Aquarius. The radiant rises shortly before 3:30am and astronomical twilight begins an hour later. There’s perhaps another half hour of visibility after that. The peak will occur Thursday morning where 20 meteors per hour or more might be seen.

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

Addendum

The sky dome for 4:30 am May 6, 2021. The Eta Aquariid radiant is near Jupiter. It looks like
two other minor meteor showers are active then with only a handful of meteors an hour
compared to the Eta Aquariids’ somewhat higher rates. The funny looking “n” character
next to Aquariid is the Greek letter Eta. Chart created using Stellarium.
Halley's meteor shower
We get two meteor showers from Halley’s Comet. The Orionids, when Halley is approaching
the inner solar system, and the Eta Aquariids when it’s leaving.
Credit my LookingUp program.

04/27/2021 – Ephemeris – What is the opposite of the Harvest Moon effect?

April 27, 2021 Comments off

This is Bob Moler with Ephemeris for Tuesday, April 27th. Today the Sun will be up for 14 hours and 4 minutes, setting at 8:43, and it will rise tomorrow at 6:36. The Moon, 1 day past full, will rise at 9:43 this evening.

Let’s think back to last fall and the Harvest Moon. The big deal about the Harvest Moon is the Moon lingers, rising or being bright in twilight to help illuminate the harvesters of old by effective lengthening the effects of daylight. The spring bright Moon after full moon rises much later night to night. Six months ago the difference in the rise times of the Moon between the full moon and the next day was 20 minutes. Today the Moon will rise 96 minutes later than it did yesterday. The reason is the beside moving eastward, it is also moving southward to where the Sun was in late fall. So it rises much later each night than it did after full moon last fall. As it is the dark skies are moving to later and later in the evening due to the spring season and daylight time.

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

Addendum

The motion of the moon
The motion of the moon near the Harvest Moon as it rises from night to night. This is looking east at where the Moon will rise, and we’re able to see below the horizon. The celestial equator, a projection of the Earth’s equator on the sky cross the horizon at an angle equal to 90 minus one’s latitude. Around my location that’s 45.5 degrees. The Moon will rise parallel to the celestial equator. Its daily orbital motion is at the shallow angle of 5 degrees. So the advance in rise times starts off at 20 minutes later each night, rather than the average 50 minutes.
Spring Moon rising angle
How the Moon’s path near a spring full moon affects its rise time interval. Note the scale is not the same as the top image. Created using Cartes du Ciel (Sky Charts).

04/23/2021 – Ephemeris – The gibbous Moon tonight

April 23, 2021 Comments off

This is Ephemeris for Friday, April 23rd. Today the Sun will be up for 13 hours and 53 minutes, setting at 8:38, and it will rise tomorrow at 6:43. The Moon, halfway from first quarter to full, will set at 5:49 tomorrow morning.

The Moon tonight is bright. The sunrise line or terminator on the Moon is crossing the large gray plain called Oceanus Procellarum, the largest of the Moon’s seas. These seas were figments of the first telescopic observer’s imagination. They are really huge impact basins into which interior lava flowed. On the upper left edge of the moon near the terminator is a bright spot visible in binoculars. In a telescope it is a crater called Aristarchus. It is a fairly new crater, probably 450 million years old. As a rule the brighter the crater the newer it is. Aristarchus is the brightest spot on the moon when it is seen during a full moon. Over the years visual astronomers have seen hazes and bright spots from time to time in and near Aristarchus.

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

Addendum

The Moon tonight
The Moon as it might be seen in a small telescope tonight, April 23, 2021 at 10 pm. Created using Stellarium.
Aristarchus close up
The impact crater Aristarchus, in the center, is 24 miles or 40 kilometers in diameter and approximately 450 million years old. Credit: Lunar and Planetary Institute.

04/19/2021 – Ephemeris – The Moon tonight, Yutu the Jade Rabbit

April 19, 2021 Comments off

This is Ephemeris for Monday, April 19th. Today the Sun will be up for 13 hours and 42 minutes, setting at 8:33, and it will rise tomorrow at 6:49. The Moon, 1 day before first quarter, will set at 3:47 tomorrow morning.

Let’s take a look at the Moon tonight. Binoculars or a small telescope will be handy for seeing the lunar features. The Moon will be at actual first quarter at 3 am tomorrow morning so the terminator or in this case sunrise line on the Moon will cut it nearly in half. To the naked eye the face of the Man in the Moon isn’t yet noticeable, but the top part of the upside down Chinese rabbit Yutu can be glimpsed. His ears are the seas of Fertility and Nectar, his head is the Sea of Tranquility, and the top part of his body is the Sea of Serenity. The lower part of his body and his arms pulverizing medicine with a mortar and pestle will have to wait until the Moon is nearer full. Yutu is the pet rabbit of the Chinese Moon goddess Chang’e.

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

Addendum

The Moon as it should appear at 10 pm tonight, April 19, 2021. Can you see the rabbit’s head? Created using Stellarium.
Yutu, the Jade Rabbit pounding medicine, as he appears in the lunar seas on a full moon. Rotated to fit tonight’s moon orientation. Via Wikipedia, no source provided.

04/15/2021 – Ephemeris – The Moon tonight – libration

April 15, 2021 Comments off

This is Bob Moler with Ephemeris for Thursday, April 15th. Today the Sun will be up for 13 hours and 30 minutes, setting at 8:28, and it will rise tomorrow at 6:56. The Moon, 4 days past new, will set at 12:14 tomorrow morning.

The crescent Moon tonight is in the constellation of Taurus the bull. The bright star Aldebaran will be just to the left of the Moon. In binoculars the dark oval spot visible on the Moon is the Sea of Crises or Mare Crisium a small dark lava plain. The Moon’s rotation is quite uniform, however its orbit isn’t circular, so the Moon’s appearance seems to rock a bit back and forth over the month. It’s an effect called libration. And one way to track that is to note how close the Sea of Crises is to the edge of the Moon. A week from now that sea will appear its closest to the edge. Astronomers call the edge of the Moon the limb. The phase line between day and night on the Moon is called the terminator. Now as the Moon is waxing, it is the morning or sunrise terminator.

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

Addendum

Moon's libration animation
Simulation of the Moon’s phase and libration for October 2007 by Tomruen. Image is in the Public Domain. I recognize the animation, and it can be produced using the free app Virtual Moon Atlas. A link to the app is seen in the column to the right.

04/05/2021 – Ephemeris – Saturn, Jupiter and the Moon will be seen together tomorrow morning

April 5, 2021 Comments off

This is Ephemeris for Monday, April 5th. Today the Sun will be up for 13 hours even, setting at 8:15, and it will rise tomorrow at 7:13. The Moon, 1 day past last quarter, will rise at 5:15 tomorrow morning.

By 6:30 am tomorrow morning, if it’s clear the waning crescent Moon will be seen near Saturn and Jupiter low in the southeastern sky. Saturn will be almost directly above the Moon. And Jupiter, which is much brighter than Saturn, will be farther off to the left of the Moon at the same height. At that hour, Saturn will be only 14 degrees above the horizon, while Jupiter will be only 10 degrees up. This will make telescopic viewing tough, since you’re looking through a lot of atmosphere. The planet images won’t be sharp and will be undulating due to atmospheric currents, though they are usually not as bad in the early morning as they are in the evening. Wednesday morning the Moon will be below Jupiter. However, in the coming weeks the planets will be getting higher. Both planets will be in prime evening position by August.

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

Addendum

Saturn, Jupiter and the waning crescent Moon at 6:30 am tomorrow, April 6, 2021. Created using Stellarium 0.21.0.

03/23/2021 – Ephemeris – The Moon tonight: Bay of Rainbows

March 23, 2021 Comments off

This is Bob Moler with Ephemeris for Tuesday, March 23rd. Today the Sun will be up for 12 hours and 19 minutes, setting at 7:59, and it will rise tomorrow at 7:37. The Moon, 2 days past first quarter, will set at 5:50 tomorrow morning.

A look at the Moon tonight will reveal that the sunrise line, or terminator has almost completely revealed the large Sea of Showers or Mare Imbrium to the upper left of the center of the gibbous disk. At the extreme upper left nearly completely in sunlight a very popular feature, the Bay of Rainbows or Sinus Iridium. It’s a colorful name for something that’s as gray as the rest of the Moon. It looks like a bay off of Imbrium, and has an arch like a rainbow. Its arch is the Jura Mountains, which jut into Mare Imbrium at Cape Heraclide, just catching sunlight, and Cape Laplace farther into morning. What’s cool is catching it as the sunlight is hitting the mountains while the convex floor, following the Moon’s curvature is only partially illuminated.

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

Addendum

The Moon with Sinus Iridium

The Moon a little before how it will appear tonight highlighting Sinus Iridium. By tonight the floor of Sinus Iridium should be pretty much sunlit, and the Jura mountains completely lit. Created using Virtual Moon Atlas.

 

03/09/2021 – Ephemeris – A celestial warning to keep off thin ice

March 9, 2021 Comments off

This is Ephemeris for Tuesday, March 9th. Today the Sun will be up for 11 hours and 35 minutes, setting at 6:41, and it will rise tomorrow at 7:03. The Moon, halfway from last quarter to new, will rise at 6:12 tomorrow morning.

The native Anishinaabe peoples of the Great Lakes Region, which includes the tribes of our area, have one constellation of winter I know of. It is The Wintermaker which uses many of Orion’s stars and whose arms stretch from Aldebaran in Taurus the bull to Procyon the Little Dog Star, embracing the whole of the winter sky. Now that spring is nearly here he is sinking into the west, losing to the heat of the Sun. The first constellation of spring is Curly Tail, or the Great Underwater Panther. It uses the stars of Leo the lion’s backward question mark as its curly tail and the small knot of stars that are the head of Hydra the water snake below Cancer the crab as its head. His warning: Keep off the thinning ice or break through and be snatched by the great panther that lives below.

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

Addendum

Great Underwater Panther finder animation

The Great Underwater Panther finder animation. Three frame animation of Unannotated sky, International Astronomical Union constellations, and Anishinaabe (Ojibwe) constellations of Curly Tail and Wintermaker. Click on the image to enlarge. Created using Stellarium and GIMP. Additional credits below.

The time is set for the above image is 10 pm on March 9th.

The constellation art is part of the latest versions of Stellarium. Ojibwe (Anishinaabe) constellation art by Annette S Lee and William Wilson from Ojibwe Sky Star Map Constellation Guide, ISBN 978-0-615-98678-4. There is also an Ojibwe Sky Star Map poster suitable for framing.

03/04/2021 – Ephemeris – A very crabby constellation

March 4, 2021 Comments off

Mar 4. This is Ephemeris for Thursday, March 4th. Today the Sun will be up for 11 hours and 20 minutes, setting at 6:34, and it will rise tomorrow at 7:12. The Moon, 1 day before last quarter, will rise at 1:26 tomorrow morning.

Lying between the stars Castor and Pollux in Gemini high in the southeast and the star Regulus in Leo the Lion in the east-southeast is the dimmest constellation of the zodiac, Cancer the crab. To me its 5 brightest stars make an upside down Y. There are the stars in the center of the constellation Asellus Borealis and Asellus Australis, the north and south donkeys. There’s a fuzzy spot between and just west of them called Praesepe, the manger from which they are supposedly eating. In binoculars, it resolves into a cluster of stars called the Beehive star cluster. We amateur astronomers also know it as M 44, the 44th object on 18th century comet hunter Charles Messier’s list of fuzzy objects that might be mistaken for comets.

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

Addendum

Cancer

The constellation Cancer finder chart. Created using Cartes du Ciel (Sky Charts).

The Beehive

The Beehive star cluster, M44. Its ancient name was the Praesepe or manger when glimpsed by the naked eye. Created using Cartes du Ciel (Sky Charts)

Note in the top image above the star cluster M 67 at the bottom of Cancer, near the star Acubens. M 67 requires a small telescope to spot. They are both open or galactic star clusters which lie in or very near the plane of the Milky Way, denoted by the milky band. Part of the milky band can be seen at the upper right of the chart. M 44 is quite close to us, at only 610 light years away so is physically close to the plane of the Milky Way. M67, however is 2,610 to 2,930 light years away and is quite a bit farther than M 44 from the plane of the Milky Way. It is also much older (4 billion years old) than the stars of the Beehive (600 to 700 years old).

M67 photograph

M67 is a beautiful telescopic object. Credit Nigel Sharp, Mark Hanna, AURA/NOAO/NSF.

03/03/2021 – Ephemeris – Let’s search for the naked-eye planets for this week

March 3, 2021 Comments off

This is Bob Moler with Ephemeris for Wednesday, March 3rd. Today the Sun will be up for 11 hours and 17 minutes, setting at 6:33, and it will rise tomorrow at 7:14. The Moon, 2 days before last quarter, will rise at 12:09 tomorrow morning.

Let’s search for the naked-eye planets for this week. Unfortunately the only one you’ll find is Mars. The other four are hanging out in the direction of the Sun and won’t be seen for a week or so. Mars can be found high in the west-southwest and below left of the Pleiades at 8 pm tonight. Mars will be due south of the Pleiades tonight, which from our cockeyed view of the heavens, from north of the equator, places Mars below and left of the Pleiades. The Red Planet will set at 1:20 am. Of the outer planets Mars is the fastest, being the nearest to the Sun, and to the Earth. So unlike Jupiter, Saturn, and the stars which rise and set about four minutes earlier each night, Mars sets about a minute earlier each night now.

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

Addendum

Mars south of Pleiades animation

Here’s an animation showing why Mars being south of the Pleiades doesn’t look like it in the sky. This is all about directions on the celestial sphere. This will be the position of Mars at 8 pm on March 3rd, 2021, seen in the west-southwest. It is a three frame animation. The first is without coordinate grids as one would see it from about 45 degrees north latitude. The second frame contains the equatorial grid. The lines to the upper right point to the North Pole of the sky near Polaris, so that’s north. The third frame has an alt-azimuth grid. Its lines run vertically and horizontally. Created using Stellarium and GIMP.

Binocular Moon

The moon as it might appear in binoculars at 6 am tomorrow morning March 4, 2021. Created using Stellarium.

Planets and the Moon on a single night

Planets and the Moon at sunset and sunrise of a single night starting with sunset on the right on March 3, 2021. The night ends on the left with sunrise on the 4th. There is a planet traffic jam in the morning and the symbols and labels for Jupiter and Mercury overlap. Unfortunately these planets rise too soon before the Sun to be seen for us up north. It is a great sight for Southern Hemisphere observers. Click on the image to enlarge. Created using my LookingUp program.