11/21/2022 – Ephemeris – The Pleiades or the Seven Sisters

This is Ephemeris for Monday, November 21st. Today the Sun will be up for 9 hours and 21 minutes, setting at 5:09, and it will rise tomorrow at 7:49. The Moon, 2 days before new, will rise at 6:10 tomorrow morning.

A marvelous member of the autumn skies can be found low in the east after 8 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. With binoculars, one can see over a hundred stars appear, along with the dipper shape of the brightest. In photographs, the Pleiades actually contain wisps of the dust they are currently passing through. In Greek mythology, the sisters were daughters of the god Atlas. I’ll be revisiting the Pleiades several times this autumn, winter, and before they disappear in the west in evening twilight next spring.

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

Pleiades finder animation for 8:30 pm tonight, November 21, 2022. Mars is the interloper this year, seen between the horns of Taurus the Bull. The V of stars that make up the face of Taurus the bull is a star cluster of stars called the Hyades. In Greek mythology, they are the half-sisters of the Pleiades. Created using Stellarium, LibreOffice Draw, and GIMP.

The Pleiades, about what you’d see in binoculars. To the naked eye, six or seven stars might be glimpsed. As star clusters go, it might seem small and unremarkable, but the Pleiades is nearby, and the brightest star cluster visible. Its stars are regarded by cultures around the world as female stars, generally sisters.  Credit: Mine.

08/16/2022 – Ephemeris – Scanning Sagittarius with binoculars

This is Bob Moler with Ephemeris for Tuesday, August 16th. Today the Sun will be up for 14 hours to the minute, setting at 8:46, and it will rise tomorrow at 6:47. The Moon, 3 days before last quarter, will rise at 11:15 this evening.

The Moon has left the evening sky, so let’s take another look at the constellation of Sagittarius. Its bright stars make a follow the dots image of a stout little teapot. In, around and above the teapot is a wealth of nebulae, which are clouds of gas and dust and clusters of stars. Stars are born in bunches from a cloud of gas. When enough stars are born, their stellar winds blow away the nebulosity leaving a star cluster. Use a pair of binoculars or a very low power telescope and just wander around and above the teapot, including and especially the spout on the right side. In binoculars, star clusters appear fuzzy like nebulae, however a small telescope with magnification of 20 times should resolve most of them.

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

Sagittarius in a short time exposure with added annotations. The “M” designations are objects in Charles Messier’s catalog created in the latter half of the 18th century. LSSC is the Large Sagittarius Star Cloud, SSSC is the Small Sagittarius Star Cloud. Labels are to the right of the objects they name. Credit Bob Moler.

This is the short radio program version of the August 8, 2022, Ephemeris Extra post Wandering through Sagittarius

03/03/2022 – Ephemeris – Finding Cancer the crab

This is Ephemeris for Thursday, March 3rd. Today the Sun will be up for 11 hours and 16 minutes, setting at 6:33, and it will rise tomorrow at 7:15. The Moon, 1 day past new, will set at 7:46 this evening.

The constellation of Cancer the crab is made of dim stars, which are generally connected, in constellation charts, with lines that make either the letter K or an upside down Y, which lie directly between the star pair Castor and Pollux in Gemini and Regulus in Leo. In the center of the constellation is, what to the naked-eye is a fuzzy spot called Praesepe, or the manger. The two nearby stars, one to the northeast, and one to the southeast are Asellus Borealis, and Asellus Australis, the northern and southern donkey colts feeding out of the manger. Viewing that fuzzy spot with a pair of binoculars will reveal that it’s not fuzzy at all. It resolves into a cluster of stars, which astronomers, over the years, have called the Beehive cluster. Back in the first and second century CE, the Sun entered Cancer to begin the season of summer. It’s now just a transitional constellation between the winter and spring evening skies.

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

Cancer, the crab finder chart. Note the beehive cluster, also known to amateur astronomers as M44, along with other catalog names. Prior to the invention of the telescope this cluster was known as Praesepe which means “Manger”. Click on the image to enlarge it. Created using Stellarium and GIMP.

A closer look at Cancer, noting the donkey stars Asellus Borealis and Australis feeding at the manger, Praesepe or M44, aka: the Beehive Cluster. Created using Cartes du Ciel (Sky Charts) and LibreOffice for captions. Adapted from a chart I created for the March 2022 issue of the GTAS newsletter, the Stellar Sentinel.

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

11/02/2021 – Ephemeris – Finding the Pleiades or Seven Sisters

This is Ephemeris for Election Day for some, Tuesday, November 2nd. The Sun will rise at 8:22. It’ll be up for 10 hours and 7 minutes, setting at 6:29. The Moon, 2 days before new, will rise at 6:35 tomorrow morning.

A marvelous sight in the autumn skies can be found low in the east after 8 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. However, with binoculars, one can see over a hundred stars appear along with the dipper shape of the brightest. In photographs, the Pleiades actually contain wisps of the dust they are passing through. They are a young star cluster, whose age is estimated to be one hundred million years. In Greek mythology, the sisters were daughters of the god Atlas. I’ll be revisiting the Pleiades several times this autumn, and winter, starting on Thursday.

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 the Pleiades animation for 9 p.m. in late October/early November. Created using Stellarium and GIMP.

The Pleiades, about what you’d see in binoculars.

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

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

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

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

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.

 

11/16/2020 – Ephemeris – How to find the Pleiades or Seven Sisters

This is Ephemeris for Monday, November 16th. Today the Sun will be up for 9 hours and 31 minutes, setting at 5:13, and it will rise tomorrow at 7:43. The Moon, 1 day past new, will set at 6:31 this evening.

A marvelous member of the autumn skies can be found low in the east after 8 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 could 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 and dust they are currently passing through. In Greek mythology the sisters were daughters of the god Atlas. I’ll be revisiting the Pleiades several times this autumn, winter, and as they disappear in the west in evening twilight next spring.

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

*My vision was corrected with cataract surgery a few years ago. The Pleiades now have a granular appearance now.

Addendum

Pleiades finder animation looking east at 8 pm, November 16th. Click on the image to enlarge. Created using Stellarium.

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

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

08/21/2020 – Ephemeris – Great moments in astronomy: The Great Debate in 1920

This is Bob Moler with Ephemeris for Friday, August 21st. Today the Sun will be up for 13 hours and 44 minutes, setting at 8:37, and it will rise tomorrow at 6:54. The Moon, 3 days past new, will set at 10:26 this evening.

One hundred years ago there were two lectures given to the National Academy of Science by Drs. Harlow Shapley and Heber Curtis. This became know as the Great Debate. Shapley believed that the Milky Way was the entire universe, and evidenced by the distribution of globular star clusters in the sky that the Sun was near the periphery of it, and that spiral nebulae were part of the Milky Way. Curtis on the other hand thought that the Sun was near the center of the Milky Way, however that the spiral nebulae were other island universes, or milky ways of their own. Over the next decade each was proved right in part and wrong in part. We are not near the center of the Milky Way, but those spiral nebulae were indeed other milky ways or galaxies.

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

Addendum

A drawing of the Whirlpool Galaxy, M51 (NGC 5194 & 5195) by Lord Rosse with his 72 inch telescope in the mid 19th century. This is the only “spiral nebula” I have actually seen as a spiral visually in a telescope, though not as well as he saw it. Public Domain.

With the advent of photography many spiral nebulae were discovered. The Whirlpool Galaxy, M51. Credit Scott Anttila.

This is a copy of the Press release issued for the two presentations of Harlow Shapley and Heber Curtis at the annual meeting of the National Academy of Sciences April 26, 1920 that have come to be known as the “Great Debate”. Credit NAS.

For more on the Great Debate follow this link.

Astronomy has advanced a long way in the last 100 years.  And what’s crazy is that I actually met Dr. Harlow Shapley at the opening of the Planetarium of the Grand Rapids Public Museum around 1960. I was in my first year at Grand Rapids Junior College at the time. I had been a member of the of the local astronomy club for several years by then. Two friends and I became planetarium rats and have wormed our way into volunteering to working with it before a formal structure was set up to operate it.

 

05/21/2020 – Ephemeris – A star cluster in a most unusual spot

This is Ephemeris for Thursday, 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, 1 day before new, will rise at 6:16 tomorrow morning.

High in the south at 10:30 p.m. or so is a tiny and faint constellation of Coma Berenices, or Berenice’s hair. In it are lots of faint stars arrayed to look like several strands of hair. The whole group will fit in the field of a pair of binoculars, which will also show many more stars. The hank of hair supposed belonged to Berenice II, Queen of Egypt, in the 3rd century BCE. Coma Berenices is the second closest star cluster to us at only 250 light years away, after the Hyades, the face of Taurus the bull a winter constellation. It’s in an odd spot for a galactic star cluster, which are supposed to lie in the plane of the Milky Way. It’s actually seen at the galactic pole, as far as possible away from the milky band. It’s a matter of perspective because it’s so close to us. It’s still really in the plane of the Milky Way.

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

Addendum

Coma Berenices and galactic coordinated showing how close to the galactic pole it is. The bright star Arcturus at the left edge.  Leo’s hind end is at the lower right. Created using Cartes du Ciel (Sky Charts).

Approximate 7 power binocular field of view of the Coma Berenices Star Cluster. Created using Cartes du Ciel (Sky Charts).

Note: There is another cluster in the constellation.  It’s called the Coma Cluster.  It’s a cluster of over a thousand galaxies a bit over 300 million light years away.