01/20/2022 – Ephemeris – Taurus and the half sisters of the Pleiades

This is Bob Moler with Ephemeris for Thursday, January 20th. Today the Sun will be up for 9 hours and 21 minutes, setting at 5:34, and it will rise tomorrow at 8:12. The Moon, 3 days past full, will rise at 8:23 this evening.

High in the south-southeastern sky, and above-right of Orion, is the bright star Aldebaran. It’s at one tip of a letter V of fainter stars. The group of stars is the face of the constellation of Taurus the bull. Aldebaran is the angry bloodshot eye of the bull that’s charging Orion, whose defending himself with a lion skin shield and an upraised club. The stars in the V, and many more visible in binoculars, except for Aldebaran, belong to a star cluster called the Hyades. In Greek mythology, these are the half sisters of the Pleiades, visible as a tight group of stars above them. The V of stars is actually an upside down letter A, or Aleph, the first letter of the Hebrew and Mesopotamian alphabets. This was invented when Taurus, not Aries, was host to the Sun at the spring equinox.

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  Hyades (left) and the Pleiades (right) in this photograph I took January 4, 2016. Aldebaran is the bright star at the left tip of the Pleiades (right)  of the Hyades.

Orion and Taurus finder animation for mid-January. Created using Stellarium

12/15/2020 – Ephemeris – Hyades, the face of Taurus the bull

This is Ephemeris for Tuesday, December 15th. Today the Sun will be up for 8 hours and 49 minutes, setting at 5:02, and it will rise tomorrow at 8:14. The Moon, 1 day past new, will set at 6:03 this evening.

The face of the constellation Taurus the bull looks like the letter V sideways above the rising Orion the Hunter in the east at 9 p.m. The bright star at the tip of a letter V of stars is Aldebaran. Look with binoculars at the letter V shape and you will see the stars of the Hyades star cluster The Hyades is the closest star cluster to us, at about 153 light years. And is important for that reason. Before satellites like Hipparcos and Gaia the Hyades was the only star cluster that could be directly measured by a technique called parallax, using the radius of the Earth’s orbit as one side of a surveyors enormous triangle. Its many stars at the same distance were used to determine distances of star clusters even farther away. Additional techniques based on the distance of the Hyades allowed us to measure distances to the nearest galaxies.

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

Addendum

Aldebaran in the ‘V’ shape of the Hyades (The face of Taurus the bull) with the Pleiades above. Aldebaran is not part of the Hyades, being about halfway between us and the cluster. Created using Stellarium.

HR diagram showing the Hyades and Pleiades. Credit: European Southern Observatory.

The Hertzsprung–Russell diagram or HR diagram is one of the great astronomical tools developed in the early 20th century by plotting stars by surface temperature horizontally (hot to cool, left to right) and brightness vertically. It turns out that stars in the prime of life and shining via converting hydrogen to helium lie on a diagonal line  from hot and bright from the upper left to cool and dim to the lower right. The line is called the main sequence. In plotting the Hyades stars against other star cluster stars the vertical displacement of the main sequence line is a function of the relative distances of the two star clusters from us. This is just one of the uses of the HR diagram.

 

12/08/2020 – Ephemeris – Finding Taurus the bull

This is Ephemeris for Tuesday, December 8th. Today the Sun will be up for 8 hours and 54 minutes, setting at 5:02, and it will rise tomorrow at 8:08. The Moon, 1 day past last quarter, will rise at 1:39 tomorrow morning.

Orion is the big splashy constellation in the east southeast by 9 in the evening. Above it is another famous constellation Taurus the bull. Its face is a letter V shape of stars on its side with the open end of the V to the left. The bright star at the lower left end of the sideways V is the ruddy star Aldebaran, the Bull’s angry bloodshot eye. The bull is charging down at Orion. The Pleiades, also known as the seven sisters, is the cluster of stars in his shoulder, above the V. The stars in the face of Taurus, except for Aldebaran belong to a star cluster like the Pleiades, but closer and older, called the Hyades. In Greek mythology the Hyades are half sisters to the Pleiades, all fathered by the god Atlas.

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

Addendum

Three views of Taurus the bull and Orion the hunter for 9 p.m. on December 8th. Created using Stellarium and GIMP.

The Pleiades (right) and the Hyades (left) in this photograph I took January 4, 2016. The orientation is a bit different from how it appears in early December.

12/17/2019 – Ephemeris – Hyades, the face of Taurus the Bull

Ephemeris for Tuesday, December 17th. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:03, and it will rise tomorrow at 8:15. The Moon, 2 days before last quarter, will rise at 11:14 this evening.

The face of the constellation Taurus the bull looks like the letter V sideways above the rising Orion the Hunter in the east at 9 p.m. The bright star at the tip of a letter V of stars is Aldebaran. Look with binoculars at the letter V shape and you will see the stars of the Hyades star cluster The Hyades is the closest star cluster to us, at about 153 light years. And is important for that reason. Before satellites like Hipparcos and Gaia. The Hyades was the only star cluster to be directly measured by a technique called parallax, using the radius of the Earth’s orbit as one side of a surveyors enormous triangle. Its many stars at the same distance were used to determine distances of star clusters even farther away. Additional techniques based on the distance of the Hyades allowed us to measure distances to the galaxies.

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

Addendum

Aldebaran in the ‘V’ shape of the Hyades (The face of Taurus the bull) with the Pleiades above. Created using Stellarium.

12/16/2019 – Ephemeris – Taurus Treasures

Ephemeris for Monday, December 16th. Today the Sun will be up for 8 hours and 49 minutes, setting at 5:03, and it will rise tomorrow at 8:14. The Moon, 3 days before last quarter, will rise at 9:59 this evening.

Rising in the east-southeast now is the bright star Aldebaran an orange star that’s at one end of the sideways letter V of stars that is the head of Taurus the bull. Above it is the jewel-like Pleiades or Seven Sisters star cluster. There’s more to Taurus, like it’s freakishly long horns and front part of its body. But you can say you’ve seem Taurus, if you can spot his face. That V of stars is actually a star cluster called the Hyades, the closest to the Earth, and in Greek Myth were the half-sisters of the Pleiades, also fathered by the god Atlas. Both the Hyades and Pleiades are being pursued by Orion, which is below it. He isn’t the only one following the Pleiades, the name Aldebaran means “The Follower”.

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

Addendum

An animation showing the Hyades, Taurus, Orion and the Pleiades. Click on the image to enlarge. Created using Stellarium and GIMP.

The Pleiades (right) and the Hyades (left) in this photograph I took January 4, 2016.

 

10/29/2019 – Ephemeris – Finding the Pleiades or Seven Sisters

Ephemeris for Tuesday, October 29th. Today the Sun will be up for 10 hours and 19 minutes, setting at 6:36, and it will rise tomorrow at 8:17. The Moon, 2 days past new, will set at 7:57 this evening.

A marvelous member of the autumn skies can be found low in the east northeast after 9 in the evening. It is the famous star cluster called the Pleiades or the Seven Sisters. I might also add the ‘Tiny Dipper’. Many people can spot a tiny dipper shape in its six or seven stars, and mistake it for the Little Dipper. When I was nearsighted, though corrected, I never had been able to see more than a few stars and a bit of fuzz. However with binoculars, even I can see over a hundred stars appear along with the dipper shape of the brightest. The fuzz I saw was unresolved stars, but in photographs the Pleiades actually contain wisps of the gas they are passing through currently. In Greek mythology the sisters were daughters of the god Atlas.

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

Addendum

Finding the Pleiades animation for 9 p.m. October 29, 2019. The Pleiades is surrounded by constellations I’ve described earlier this year and one yet to be described, Taurus the bull of which the cluster is a part.  The V of stars near the horizon is Taurus’ head and is another star cluster, the Hyades, the half sisters to the Pleiades. Created using Stellarium and GIMP.

The Pleiades, about what you’d see in binoculars, though not as brilliant.  One of my old photographs.  With my 11 inch f/4.5 Dobsonian using a 40mm eyepiece that gives a field of view that encompasses the Pleiades, all I can say is Wow!

The Greek Pleiades a painting by Elihu Vedder in the Metropolitan Museum of Art, New York City. Public Domain.

03/26/2019 – Ephemeris – Mars is approaching the Pleiades this week

Ephemeris for Tuesday, March 26th. Today the Sun will be up for 12 hours and 27 minutes, setting at 8:02, and it will rise tomorrow at 7:33. The Moon, 2 days before last quarter, will rise at 2:38 tomorrow morning.

Daylight time and spring time are catching up with us with the Sun setting now just after 8 p.m. By 9 p.m. tonight the brighter stars appear and most of the well known constellations will be recognizable. Looking off to the west at that time the famous star group of the Pleiades, or Seven Sisters will appear. Folks with good eyesight can see six or maybe even seven of its stars. Tonight, right below the Pleiades is a bright reddish star. It would be the 22nd of the first magnitude stars, except it’s not a star. It’s a wanderer, according to the ancient Greeks, one of seven*. They called it Ares the god of war. The Romans turned it into Mars. Over the week Mars will be closing in and passing by the Pleiades this weekend.

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

Addendum

The western sky at 10:22 last night March 25, 2019. Mars appears below the Pleiades in zodiacal light. Credit, mine – Canon EOS Rebel T5 18mm f.l., f/3.5, 8 sec. ISO 12,800.

Mars tiptoeing past the Pleiades nightly from March 26th to April 1st, 2019 at 9 p.m. Looking west. Created using Stellarium and GIMP.

The letter V of stars to the left of the Pleiades is the Hyades, in mythology the half sisters to the Pleiades.  It is also the face of Taurus the bull.

* We get the word planet from the Greek planētes meaning wander.  Five are the classical planets, Mercury, Venus, Mars, Jupiter, and Saturn.  The other two are the Sun and Moon.  The other celestial objects were the fixed stars.  Other things that appear in the sky, like comets, novae and meteors were thought to be in the Earth’s atmosphere.

04/24/2018 – Ephemeris – Venus will be south of the Pleiades tonight

Ephemeris for Tuesday, April 24th. The Sun rises at 6:43. It’ll be up for 13 hours and 55 minutes, setting at 8:39. The Moon, 2 days past first quarter, will set at 4:51 tomorrow morning.

Tonight the brilliant planet Venus will be just south of the Pleiades, also known as the Seven Sisters star cluster. From our cockeyed position on the Earth about half way from the equator and the North Pole. The sky in the east and west, low in the sky, is tilted about the same angle, namely about 45 degrees. If you’re listening to this program from other than Northern Michigan the angle will be the same as your latitude. So instead of south being down, as one would expect when looking to the south, south is to the lower left when looking to the west. On this program Thursday, Friday and Monday I’ll be talking about Venus and what the ancients found out about the planet in the days before the telescope was invented.

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

Addendum

Venus, Pleiades, Aldebaran with the Hyades star cluster and Orion are seen in the west at 9:45 p.m. April 24, 2018. Venus is south of the Pleiades. Created using Stellarium.

A closer look at Venus and the Pleiades with the coordinate grid added. The lines that run from upper right to lower left are lines of right ascension, analogous to longitude lines on the Earth. To the upper right is north and lower left is south. The other lines are those of declination. Like latitude lines on the Earth, they run east and west. Created using Stellarium.

12/15/2017 – Ephemeris – Taurus, Bullish on Winter

Note:  The title of this post I’ve taken from an article I wrote for the December 1999 issue of the Stellar Sentinel, the monthly newsletter of the Grand Traverse Astronomical Society, which I will reprint with some tweaks, as the addendum to this post.  Winter will arrive in six days, though I’m not particularly bullish on it, but it fits the constellation I’m talking about today.

Ephemeris for Friday, December 15th. The Sun will rise at 8:12. It’ll be up for 8 hours and 50 minutes, setting at 5:02. The Moon, 3 days before new, will rise at 6:25 tomorrow morning.

Low in the east-southeast at 9 p.m. is the constellation of Orion the giant hunter. Above him is Taurus the bull. His face is a letter V shape of stars lying on its side with the bright orange-red star Aldebaran at the bottom tip of the V as its angry blood-shot eye. Orion is depicted in the sky facing him with club in one hand and a shield in the other the approaching and in some depictions charging Taurus. The V of stars is a star cluster called the Hyades. The Pleiades are in his shoulder above. Taurus, in Greek mythology, was the guise the god Zeus when he carried off the maiden Europa. Europa’s still with him, sort of, as the intriguing satellite with a buried ocean orbiting Zeus’ Roman equivalent the planet Jupiter.

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

Addendum

Three views of Taurus the bull and Orion the hunter for about  p.m. in December.

The Hyades (lower left) and the Pleiades (upper right). My photograph from many years ago BD (Before Digital).

The first constellation of winter to appear is probably a toss-up between Auriga the charioteer and Taurus the Bull. Auriga never quite disappears, or at least Capella its brightest star is circumpolar and never quite sets here in Northern Michigan. But Auriga sneaks up slowly in the northeast. Taurus on the other hand makes a grand entrance on autumn evenings preceded by the Pleiades, the Seven Sisters star cluster.

Taurus’ brightest star is Aldebaran, the bull’s angry bloodshot eye. It is at the left tip of a letter V of stars that is the bull’s face. Above the V are single stars that form the tips of its very long horns. Other stars below form the front legs of this beast. That’s it. Only the front part of the bull appears in the sky. In its shoulder are the Pleiades.

According to Greek mythology Taurus represents the god Zeus, the Roman Jupiter, who, in the disguise of a bull abducted the beautiful maiden Europa. This isn’t the only celestial disguise of Zeus. Cygnus is the disguise of Zeus in the famous Leda and the swan affair.

The Pleiades and the Hyades, the V-shaped star cluster of Taurus’ head also have their places in Greek Mythology. The Hyades and Pleiades are half sisters of each other who share Atlas as their father. But it is the Pleiades which are more prominent and have more stories about them. It is the Pleiades that are pursued by Orion the hunter, the central constellation of winter. And since the Pleiades are west of Orion it does appear that Orion continues to chase them around and around the sky daily. To the Kiowa Indians the Pleiades were also young maidens. As the story goes they were being chased by a large bear. The Great Spirit placed them on what we know today as Devil’s Tower in Wyoming to keep them out of reach of the bear. It is said that even today the sides of this tower show the scars of the bear’s claws. Devil’s Tower was the prominent landmark in the movie Close Encounters of the Third Kind. To the Anishinaabek native peoples around here the Pleiades is the “Hole in the Sky” or the seven sweating stones that are heated for the sweat lodge ceremony.

What do we know about Taurus today? Aldebaran is an orangish giant star which lies at a distance of 65 light years. It doesn’t belong to the Hyades, which is about 151 light years away. Aldebaran’s diameter is 40 times the Sun’s, about the diameter as the orbit of Mercury. It’s only 1.7 times tha mass of the Sun. Aldebaran shines at 153 times the Sun’s output.

Aldebaran appears to be part of the Hyades cluster, but it is less than half the distance to this most important star cluster. Though less prominent as the Pleiades, the Hyades is the most important star cluster in the heavens. The reason is because the Hyades was until recently the only star cluster close enough to get an accurate distance measurement by direct means. That direct means is parallax, measuring the shift of the star’s position in the sky due to the earth’s changing position in orbit of the Sun. The Hipparcos satellite has been refining these parallaxes over the past few years. Its measurement of the distance of the Hyades cluster is 151 light years give or take a bit less than a light year. The Hyades distance is the basis for all more distant measurements to the ends of the known universe.

The Hyades is a good binocular object with over 100 stars visible. The cluster actually overflows the binocular’s field of view. This cluster is also known as the Taurus Moving Cluster because its stars are receding towards a point northeast of Orion’s Betelgeuse.

Of course the splashiest part of Taurus is the Pleiades. For people with good vision 6 or more stars can be seen. I can see 4 or 5 stars and fuzz, which are unresolved stars. Many, who see the Pleiades for the first time, think the tiny pattern of stars is the Little Dipper. The stars do indeed look like a tiny dipper, with a nice bowl and a sawed off handle. And that’s what I call it: the Tiny Dipper. The big surprise of the Hipparcos distance measurements is the distance of the Pleiades. The generally accepted distance was about 410 light years. Hipparcos measured 375 light years. This means that the stars of the Pleiades are somewhat dimmer than believed before. Pleiades prior measurement was based on photometric or brightness measurements with the stars of the Hyades and other stars of the same type and known brightness and distance. So it turns out in the case of the Pleiades that the former measurements weren’t as accurate as thought, and means we have more to understand about stellar evolution as it relates to star brightness. Or perhaps Hipparcos is wrong. And interesting debate and more measurements are sure to follow.

The age of the Pleiades is thought to be around 100 million years, young compared to the Sun’s 4.6 billion years. Long exposure photographs and some telescopes can still spot the remaining wisp’s of the nebulae they were born from. The material is probably dust simply reflecting the light of the stars in the cluster.

Taurus is a great constellation to scan with a pair of binoculars.

11/06/2017 – Ephemeris – Taurus’ angry red eye, Aldebaran

Ephemeris for Monday, November 6th. The Sun will rise at 7:27. It’ll be up for 9 hours and 57 minutes, setting at 5:24. The Moon, 3 days past full, will rise at 7:52 this evening.

Last night the Moon passed in front of or occulted the bright star Aldebaran. Above right of Moon tonight is Aldebaran the bright orange star with a V shape of other stars in the face of Taurus the bull. Aldebaran appears at the lower left tip of that letter V laying on it’s side. With the bright Moon, it might take binoculars to pull out the faint stars of the V. Aldebaran isn’t actually part of the group, called the Hyades star cluster. The cluster is about 153 light years away, while Aldebaran is 65 light years away. The star has an orange hue because its surface is cooler than the Sun’s. However Aldebaran is 44 times larger in diameter, and shines 425 times brighter than the Sun. The name Aldebaran means “Follower” because it follows the Pleiades star cluster above it.

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

Addendum

Aldebaran in the Hyades (unlabeled), with also the Pleiades, unlabeled, at the top and the Moon. at 9 p.m., November 6, 2017. Created using Stellarium.