05/16/2023 – Ephemeris – Regulus, the Little King Star

This is Ephemeris for Tuesday, May 16th. Today the Sun will be up for 14 hours and 51 minutes, setting at 9:05, and it will rise tomorrow at 6:12. The Moon, 3 days before new, will rise at 5:08 tomorrow morning.

Regulus is the brightest star in the constellation of Leo, the lion at the bottom of the backward question mark that is the head and mane of Leo. It’s in the southwest at 10 pm. Alluding to the lion’s status in the animal kingdom, Regulus is the little king star. It is dead last in order of brightness of the 21 brightest first magnitude stars, 1/13th the brightness of Sirius the brightest nighttime star, now lost in the evening twilight glow. To the Babylonians it was the king, the 15th of their constellations, that marked the passage of the Sun. Regulus is about 79 light years away, and 288 times the brightness of the sun. It is a rapidly spinning ellipsoid 3 times the sun’s diameter, rotating in just under 16 hours.

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

Regulus and Leo and the other stars and planets in the western sky at 11 pm, May 16, 2023. Created using Stellarium.

05/15/2023 – Ephemeris – Why are crows black?

This is Bob Moler with Ephemeris for Monday, May 15th. Today the Sun will be up for 14 hours and 49 minutes, setting at 9:04, and it will rise tomorrow at 6:13. The Moon, 3 days past last quarter, will rise at 4:47 tomorrow morning.

The small constellation of Corvus the crow is located low in the south at 10:30 this evening. It’s made of 6 dim stars, the pattern is a distinctive but distorted box with two stars in the upper left corner and two stars in the lower right 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 above the southern horizon. In Greek mythology Corvus, then white, was the god Apollo’s pet who once bid the crow to take a cup and fetch him some water. Corvus, however, dallied and waited for a green fig to ripen. Corvus then grabbed a snake and returned with a story on how the snake had delayed him. The angry Apollo saw through the story and turned the crow black.

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

Corvus, Crater and Hydra finder chart. The chart was made for earlier in the month, so when it’s dark enough to see them, the constellations will have shifted to the west or right. Created using Stellarium and GIMP.

05/12/2023 – Ephemeris – Finding Virgo the virgin in the evening sky

This is Ephemeris for Friday, May 12th. Today the Sun will be up for 14 hours and 42 minutes, setting at 9:00, and it will rise tomorrow at 6:17. The Moon, at last quarter today, will rise at 3:44 tomorrow morning.

One of the large constellations we see in the south at 11 p.m. can be found using the Big Dipper overhead, follow the arc of the handle to the bright star Arcturus, then straighten the arc to a spike to reach Spica, a bright blue-white star in the south. Spica is the brightest star in the constellation Virgo, the virgin. She represents the goddess of the harvest, Virgo is holding a sheaf of wheat in depictions of her, and Spica is placed at the head of the sheaf. In the space between Spica and Leo the lion to her upper right is, a great cluster of thousands of galaxies just below naked eye visibility. The Virgo Cluster. Inside that cluster is galaxy M87, in whose center lies a black hole with the mass of 6.5 billion suns. The center of the cluster is at about 54 million light years away.

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 Virgo from the Big Dipper at 11 pm, May 12. There are no planetary interlopers this year. The small + sign marks the zenith, and the image faces south. Created using my LookingUp app, with captions added using LibreOffice Draw.

Virgo finder animation with Leo added as an aid for 11 p.m. tonight. Created using Stellarium and GIMP.

Markarian’s Chain, a small part of the Virgo Cluster of galaxies. Click or tap on the image to enlarge it. Credit: Daniel Dall’Olmo.

05/11/2023 – Ephemeris – Finding Hydra the water snake

This is Ephemeris for Thursday, May 11th. Today the Sun will be up for 14 hours and 40 minutes, setting at 8:59, and it will rise tomorrow at 6:18. The Moon, 1 day before last quarter, will rise at 3:17 tomorrow morning.

Low in the south and southwestern sky at 10 p.m. and later can be found the constellation of Hydra the water snake, the longest constellation of all. Unlike the monster of the same name, this Hydra has but one head, which is its most distinctive part. At 11 p.m. the head of Hydra is located between the bright stars Procyon in the west and Regulus in Leo the lion in the southwest. Hydra’s head is a small but distinctive group of 6 stars that make a drooping loop to the right. The rest of Hydra wends its way above the southern horizon below the bright blue star Spica in Virgo. Some delineations of Hydra have the tail tickling the constellation Libra, the balance which has just risen in the southeast.

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 Hydra, the water snake animation showing nearby constellations and stars mentioned in the program. Click or tap on the image to enlarge it. Created using Stellarium, and GIMP.

05/08/2023 – Ephemeris – How to find Leo the lion in the sky

This is Ephemeris for Monday, May 8th. Today the Sun will be up for 14 hours and 32 minutes, setting at 8:56, and it will rise tomorrow at 6:22. The Moon, 3 days past full, will rise at 12:57 tomorrow morning.

At 10 p.m. the spring constellation of Leo the lion will be high in the south. It can be found by locating the Big Dipper high overhead and imagining that a hole were drilled in the bottom of the bowl to let the water leak out. It would drip on the back of this giant cat. The Lion is standing or lying facing westward. His head and mane are seen in the stars as a backwards question mark. This group of stars is also called the sickle. The bright star Regulus is at the bottom, the dot at the bottom of the question mark. A triangle of stars, to the left of Regulus, is the lion’s haunches. Leo contains some nice galaxies visible in moderate sized telescopes. The stars in Leo’s part of the sky are fewer than those in the winter sky.

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 Leo the lion from the Big Dipper with no lines. The orientation is for 10 pm, May 8th. Can you find Leo? The Big Dipper? Created using Cartes du Ciel (Sky Charts).

Using the Big Dipper to find Leo. The orientation is for 10 pm on May 8th. For any other time, the orientation would be different, as would the position of the zenith (overhead point). Created using my LookingUp app.

Leo, with drawing of a lion. Created using Stellarium.

Note the star at the left end of Leo is named Denebola. There are several stars that start with “Deneb”. Deneb must mean tail in Arabic because most star names are Arabic in origin. Denebola is the tail of the lion. Deneb Kaitos is the tail of the autumn constellation of Cetus the whale, and Deneb itself is the tail of the summer constellation of Cygnus the swan.

04/18/2023 – Ephemeris – Orion rotates 90 degrees from rising to setting

This is Bob Moler with Ephemeris for Tuesday, April 18th. Today the Sun will be up for 13 hours and 37 minutes, setting at 8:31, and it will rise tomorrow at 6:52. The Moon, 2 days before new, will rise at 6:43 tomorrow morning.

As the constellation of Orion the hunter, that dominated our winter skies, moves into the west in the evening, it will have rotated 90 degrees from its rising orientation. As we saw it rising last November, its three belt stars were nearly vertically aligned. Now, as Orion nears the western horizon, those belt stars have rotated to be almost horizontal. The same is true of Gemini’s two brightest stars, Castor and Pollux. They are the two stars above red Mars, which is now halfway through Gemini on its eastward travels. Orion, a minor Greek hero, is most famous for how he died. I know of three versions, all different. The one that fits Orion’s current setting is that he was killed by the sting of a giant scorpion. So he must flee the sky before Scorpius the scorpion rises, which is around midnight tonight.

This amount of rotation between rising and setting is only true for latitudes near 45 degrees north or south, such as Northern Michigan, and objects near the celestial equator. The rotation for other latitudes would be 2 x (90 – latitude) for equatorial celestial objects. The name given for the term (90 – latitude) is colatitude.  90 degrees is the latitude of the Earth’s poles.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –4 hours). They may be different for your location.

Addendum

When Orion is rising, its belt stars are nearly vertically aligned. Castor and Pollux, too, appear nearly vertically aligned. This was for November 30, 2022, at 9 pm. Mars was near opposition then and quite close to the Earth, so it had shown quite brightly. Created using Stellarium and LibreOffice Draw.

Orion’s belt stars show that the constellation has rotated about 90 degrees from their rising orientation. This is for 10 pm, April 18, 2023. Note that Venus is the Evening Star now, and Mars is much dimmer, as the Earth has moved ahead and away from it. Created using Stellarium and LibreOffice Draw, for the added labels.

02/10/2023 – Ephemeris – Finding Orion’s greater hunting dog, Canis Major

This is Bob Moler with Ephemeris for Friday, February 10th. Today the Sun will be up for 10 hours and 13 minutes, setting at 6:04, and it will rise tomorrow at 7:49. The Moon, 3 days before last quarter, will rise at 11:14 this evening.

The great winter constellation or star group, Orion the hunter, is located in the southern sky at 9 p.m. His elongated rectangle of a torso is vertical. In the center of the rectangle are three stars in a line that make his belt. As a hunter, especially one of old, he has two hunting dogs. The larger, Canis Major, can be found by following the three belt stars of Orion down and to the left. They point to Sirius, the brightest nighttime star, also known as the Dog Star. It’s in the heart of a stick figure dog low in the southeast facing Orion that appears to be begging. There’s a fine star cluster, called Messier, or M 41, at the 5 o’clock position from Sirius. It’s easily visible in binoculars or a small telescope.

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

Orion and Canis Major animation for earlier than 9 in the evening. Created using Stellarium and GIMP.

02/09/2023 – Ephemeris – Orion’s Belt stars

This is Ephemeris for Thursday, February 9th. Today the Sun will be up for 10 hours and 10 minutes, setting at 6:02, and it will rise tomorrow at 7:50. The Moon, halfway from full to last quarter, will rise at 10:07 this evening.

Orion’s belt of three stars is one of the most noticeable star groupings in the sky. There are no other groups of three bright stars in a straight line visible anywhere else in the sky. The star’s names from left to right are Alnitak, Alnilam and Mintaka. They are actually a bit farther away than the other bright stars of Orion. Alnilam, the center star, is over three times the distance of red giant Betelgeuse above them and over twice as far as blue white giant star Rigel below them. Alnilam is 375 thousand times brighter than the Sun according to the SIMBAD Astronomical Database. These three stars were also known as Frigga’s Spindle by the Norsemen. Frigga also known as Freya is the goddess from which we get the name of the day of the week Friday.

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

Orion’s named stars, including the belt stars. Created using Stellarium.

01/19/2023 – Ephemeris – Gemini, twins with a secret

This is Ephemeris for Thursday, January 19th. Today the Sun will be up for 9 hours and 19 minutes, setting at 5:33, and it will rise tomorrow at 8:13. The Moon, 2 days before new, will rise at 7:38 tomorrow morning.

Another famous winter constellation is Gemini. The constellation of Gemini the Twins is visible halfway to the zenith in the east, at the top and left of Orion the hunter, at 9 pm. The namesake stars of the two lads, are the two bright stars at the left end of Gemini, and are high and are due east. Castor is on top, while Pollux is below. From them come two lines of stars that outline the two, extending horizontally toward Orion. In Greek mythology the lads were half brothers, Castor was fathered by a mere mortal, while Pollux was fathered by Zeus, but were born together as twins. When Castor was killed during the quest for the Golden Fleece, Pollux pleaded with Zeus to let him die also, so Zeus placed them together in the sky.

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

Gemini finder animation for the second half of January 2023. It’s dated because Mars is dawdling in Taurus near the Pleiades. Mars is now back to heading eastward once again, after being in retrograde or westward motion as the Earth passed it in early December. Mars will officially enter Gemini in March. Created using Stellarium, and GIMP.

01/16/2023 – Ephemeris – Orion’s great nebula

This is Bob Moler with Ephemeris for Dr. Martin Luther King Jr. Day, Monday, January 16th. Today the Sun will be up for 9 hours and 13 minutes, setting at 5:29, and it will rise tomorrow at 8:15. The Moon, 2 days past last quarter, will rise at 3:52 tomorrow morning.

The brightest interstellar cloud visible in our skies is the Great Orion Nebula. The word nebula is related to the Latin “nebulum” for cloud. The constellation of Orion is filled with nebulae, most of it are dim or dark. The Great Orion Nebula is in Orion’s sword. The sword is what looks like three stars that look dimmer than the three belt stars hanging from the belt. And there are more than three stars here. Around the stars that appear as the center of the sword stars, to the eye, can be seen a haze in binoculars. A telescope with a wider aperture and low power can see detail in the cloud. With more magnification, a clutch of four baby stars can be spotted in the brightest part of the nebula. They light up the nebula and are called the Trapezium.

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

Orion is lousy with gas and dust. A regular star factory, or nursery. The red nebulae show the predominance of hydrogen in here. In actuality, the Great Orion Nebula vastly outshines all the other nebulae in Orion. The white nebulosity to the right of Rigel is the Witches Head nebula, probably the reflection of Rigel’s light off a dust cloud. Base image by Bernal Andreo, via Wikipedia. Annotations were created by myself.

The Great Orion Nebula (M42) long exposure photograph by Scott Anttila. Includes all the sword stars.