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Posts Tagged ‘Aldebaran’

12/29/2017 – Ephemeris – Last occultation of the star Aldebaran by the Moon is tomorrow night

December 29, 2017 1 comment

Ephemeris for Friday, December 29th. The Sun will rise at 8:19. It’ll be up for 8 hours and 51 minutes, setting at 5:10. The Moon, half way from first quarter to full, will set at 5:08 tomorrow morning.

We have one last cool astronomical event that can be seen from here in 2017. Of course, weather permitting. Tomorrow night the Moon will occult the bright star Aldebaran in Taurus the bull from 6:17 to 7:17 p.m. I’m not dabbling with the black arts here, even though I’m using the Occult 4 program to find it. In astronomy occult is a verb meaning to hide, and the event is called an occultation. The Moon will appear to move in front of, or hide the star Aldebaran. At 6:17 p.m. Aldebaran will disappear at the dark edge of the Moon at its 8 o’clock position. Binoculars will be needed to spot the star against the glare of the bright Moon before the event. Aldebaran will pop out from behind the Moon at a bit above the 3 o’clock position at 7:17 p.m.

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

Addendum

Occultation visibility map

Occultation visibility map for the occultation of Aldebaran by the Moon for us in the Unites States, the early evening of December 30, 2017. Created using Occult 4 by IOTA.

Occultation start

Occultation start 6:17 p.m. December 30, 2017. as seen from the Grand Traverse area of Michigan. Actual times may vary depending on your location. Created using Stellarium.

Occultation end

Occultation end 7:17 p.m. December 30, 2017. as seen from the Grand Traverse area of Michigan. Actual times may vary depending on your location. Created using Stellarium.

Note the times are for the Traverse City/Interlochen area. It will vary by a few minutes for northern lower Michigan.  The position angles of the entrance and exit points of Aldebaran will also be different.

Otherwise use a planetarium program like Stellarium to preview the event. However, set the program for topocentric coordinates. In Stellarium that’s in the Configuration window, Tools Tab and check the Topocentric coordinates box. Topocentric coordinates are the apparent positions for your location on the Earth. So also make sure your location is correct. The geocentric conjunction of the two bodies will be December, 31, 0:49.2 UT, so it will occur after midnight on the morning of December 31st for locations in northern Europe and Asia.

Program Note

The January preview will be an Ephemeris Extra post on December 31st.

 

 

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

December 15, 2017 1 comment

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

Taurus and Orion

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

Hyades and Pleiades

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

November 6, 2017 1 comment

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

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.

11/05/2017 – Ephemeris Extra – There will be an Occultation of Aldebaran tonight*

November 5, 2017 1 comment

This posting will not be broadcast.

* Or tomorrow morning, depending where you are.

Ephemeris extra for Sunday, November 5th. The Sun will rise at 7:25. It’ll be up for 10 hours and 5 minutes, setting at 5:25. The Moon, 2 days past full, will rise at 7:01 this evening.

Tonight just after 8 p.m. the bright star Aldebaran will disappear at the left edge of the Moon. Aldebaran is angry red eye of Taurus the bull. The star will reappear at the dark upper right edge of the Moon. Start looking at 8 p.m. or before. Use binoculars or a small telescope to spot the star against the glare of the bright Moon. The star is nowhere as bright as shown in the illustrations below. Star appearances and disappearances appear instantaneous, unlike what the illustrations show.

Aldebaran Occultation begins at 8:07 p.m. EST (1:07 UTC Nov 6th)
Aldebaran Occultation ends at 9:00 p.m. EST (02:00 UTC Nov 6th)

Note the times are for the Traverse City/Interlochen area. It will vary by a few minutes for northern lower Michigan.  The position angles of the entrance and exit points of Aldebaran will also be different.

Otherwise use a planetarium program like Stellarium to preview the event. However, set the program for topocentric coordinates. In Stellarium that’s in the Configuration window, Tools Tab and check the Topocentric coordinates box. Topocentric coordinates are the apparent positions for your location on the Earth. So also make sure your location is correct. The geocentric conjunction of the two bodies will be November 6, 2:42.9 UTC, so it will occur after midnight on the morning of November 6th for locations in northern Europe and Asia.

Addendum

Occultation Map

Occultation Map for the occultation of Aldebaran by the Moon . Credit Occult 4 program from IOTA.org.

Occultation start

Aldebaran at the start of the occultation at 8:07 p.m. for the Traverse City/Interlochen area. Created using Stellarium.

Occultation end

Aldebaran at the end of the occultation at 9:00 p.m. for the Traverse City/Interlochen area. Created using Stellarium.

11/03/2017 – Ephemeris – The Sun is the topic at tonight’s GTAS meeting

November 3, 2017 Comments off

Ephemeris for Friday, November 3rd. The Sun will rise at 8:23. It’ll be up for 10 hours and 5 minutes, setting at 6:28. The Moon, 1 day before full, will set at 8:35 tomorrow morning.

This evening the Grand Traverse Astronomical Society will hold its monthly meeting at the Northwestern Michigan College’s Rogers Observatory at 8 p.m. with a program featuring member Don Flegel in a talk about the Sun. Don’s the keeper of our solar telescope and wanted a good excuse to learn more about the Sun, so he decided to study up and give this talk. That’s how I do it.

After the talk, at 9 p.m. there will be a star party, if it’s clear, to view the heavens including the Moon. The observatory is located south of Traverse City, on Birmley Road between Garfield and Keystone roads.

It’s time to change our clocks again at 2 a.m. Sunday. Turn your clocks back one hour. That’s Fall Back one hour for a bit of extra sleep.

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

Addenda

Don Flegel at Fishtown

Don Flegel, in the foreground, with the society’s solar telescope assisting a person viewing the Sun at he Leland Heritage Festival 2017 at Fishtown.  Man in the background in the blue cap is Gary Carlisle.  The telescope in the middle is mine.

Occultation of Aldebaran by the Moon Sunday Night

Occultation Map

Occultation Map for the occultation of Aldebaran by the Moon . Credit Occult 4 program from IOTA.org.

For the Traverse City/Interlochen area:

Aldebaran Occultation start 8:07 p.m. Nov 5th (01:07 UT Nov 6th)
Aldebaran Occultation end 9:00 p.m. Nov 5th (02:00 UT Nov 6th)

I’ll have an Ephemeris Extra posting, Sunday November 5th with more information.

09/12/2017 – Ephemeris – The Moon will hide the bright star Aldebaran after sunrise this morning

September 12, 2017 Comments off

Ephemeris for Tuesday, September 12th. The Sun will rise at 7:18. It’ll be up for 12 hours and 40 minutes, setting at 7:58. The Moon, 1 day before last quarter, will rise at 12:13 tomorrow morning.

This morning during daylight at around 8:40*. the bright star Aldebaran will disappear behind the Moon. Binoculars or a small telescope can be used to spot Aldebaran, the bright star in the constellation Taurus the bull’s eye. Taurus and the rest of the winter constellations are visible before sunrise. The sky needs to be absolutely clear to be able to spot the event. The star will be seen to approach the bright side of the Moon. The star will reappear around 9:53 a.m.* on the dark western edge of the Moon. These events are called occultations. They come from the word occult, which means hidden. In actuality the solar eclipse of three weeks ago was a spacial case of an occultation for those in the path of totality.

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

* The disappearance and appearance times for Aldebaran are within a couple of minutes for Western Michigan.  For other locations in the occultation path Stellarium will give pretty good times for the events by modeling the occultation as I did below.  Like a solar eclipse where you are determines the timing of the event.

Addendum

Occultation map

Map of where the occultation is visible. For the area bounded in red, the occultation is visible in the daytime. Credit: Occult4 by IOTA.

Position of the Moon in the sky

Position of the Moon in the sky near the start of the occultation, 8:35 a.m. September 12, 2017. Created using Stellarium.

Aldebaran and the Moon at 8:35 a.m.

Aldebaran and the Moon at 8:35 a.m. September 12, 2017. Created using Stellarium.

Aldebaran reappearing from behind the Moon

Aldebaran reappearing from behind the Moon at 9:53 a.m. September 12, 2017. Created using Stellarium.

 

03/03/2017 – Ephemeris – Astronomy talk and star party tonight and the occultation of Aldebaran tomorrow night

March 3, 2017 Comments off

Ephemeris for Friday, March 3rd.  The Sun will rise at 7:15.  It’ll be up for 11 hours and 17 minutes, setting at 6:33.  The Moon, 2 days before first quarter, will set at 12:36 tomorrow morning.

Tonight the Grand Traverse Astronomical Society will present a talk by Becky Shaw on international observatories at 8 p.m. at Northern Michigan College’s Rogers Observatory.  Also tonight at the observatory, there will be viewing of the Moon and other wonders of the March skies.  Tomorrow night shortly after 11 p.m. the bright star Aldebaran in Taurus the bull will be covered or occulted by the Moon for about half of the IPR listening area.  It will be seen by observers south of a line from Leland to south of Mancelona centered on 11:13 p.m.  The farther south one is the longer the occultation will last.  Start looking by 11 p.m. and check my yesterday’s blog post for more information.

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