Archive
02/22/2018 – Ephemeris – The blue-white star at Orion’s knee
Ephemeris for Thursday, February 22nd. The Sun will rise at 7:32. It’ll be up for 10 hours and 49 minutes, setting at 6:21. The Moon, 1 day before first quarter, will set at 1:46 tomorrow morning.
The bright star at the bottom right corner of the big upright rectangle that is the giant hunter Orion’s body in the south-southeast is Rigel. It is a white star with a bluish tinge. It compares in brightness with Betelgeuse at the opposite end of Orion’s rectangle, though it’s usually a bit brighter. The mismatch in color makes brightness comparisons difficult. Rigel is about 860 light years away, It’s 23 times the mass of the Sun, 120 thousand the times brighter than the Sun, and a diameter almost the size of the orbit of Mercury. It’s age is thought to be about 8 million years. It has a visual companion star that can be seen in amateur telescopes. It’s not that dim, but suffers by being close to the arc light brightness of Rigel.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Orion’s named stars including the belt stars. Created using Stellarium.
Rigel with its companion star as photographed through a telescope. No attribution. Source: http://washedoutastronomy.com/content/urban-orion?page=1
02/12/2018 – Ephemeris – The Winter Circle
Ephemeris for Monday, February 12th. The Sun will rise at 7:47. It’ll be up for 10 hours and 19 minutes, setting at 6:07. The Moon, 3 days before new, will rise at 6:29 tomorrow morning.
The winter skies are blessed with more first magnitude stars than any other season. Six of these stars lie in a large circle centered on the seventh, It’s called the Winter Circle. This circle is up at 9 p.m. Starting high overhead is yellow Capella in Auriga the charioteer. Moving down clockwise is orange Aldebaran in the face of Taurus the Bull. Then down to Orion’s knee we find blue-white Rigel. Down and left is the brightest star of all the brilliant white Sirius the Dog Star in Canis Major, lowest of these stars in the south-southeast. Moving up and left is white Procyon in Canis Minor, Above Procyon is Pollux in Gemini the twins. All these are centered, well not quite, on Betelgeuse the bright red star in Orion’s shoulder.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The bright stars of winter arrayed in a circle (well almost). Created using Stellarium.
02/08/2018 – Ephemeris – The wonderfully named stars of Orion
Ephemeris for Thursday, February 8th. The Sun will rise at 7:53. It’ll be up for 10 hours and 8 minutes, setting at 6:01. The Moon, 1 day past last quarter, will rise at 3:09 tomorrow morning.
The constellation of Orion the hunter is visible in the south at 9 p.m. The stars of Orion are interesting in themselves. Starting at the top left of the seven bright stars of Orion’s torso is Betelgeuse the bright red star, whose name means something like “Armpit of the Giant”. The star in Orion’s other shoulder is Bellatrix the “Amazon Star”. Below are the three stars of Orion’s belt, from left to right; Alnitak, Alnilam and Mintaka. Their names mean “Girdle”, “Belt of Pearls”, and “Belt” respectively. Down to Orion’s knees we look on the left to the star Saiph pronounced ‘safe’ which means “Sword”, though it is some ways from the stars of Orion’s sword. Finally there’s the bright blue-white star Rigel whose name means “Left Leg of the Giant”.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The named stars of Orion. Created using Stellarium.
Betelgeuse, pronounced Beetlejuice is the name of a 1988 movie, where Betelgeuse (spelled properly) is a particularly mischievous demon. Don’t say his name three times, or he’ll come and ‘help’ you. Oops, I did. It is a red giant star near the end of its life.
Bellatrix, is now known to most of us now as the first name as the first name of Bellatrix Lestrange from J. K. Rowling’s Harry Potter book and movie series. Other members of the Black family have astronomical names, such as Regulus (Leo) Black, and Sirius (Canis Major) Black.
The names of the belt stars were taught to me by Evelyn Grebel of the Grand Rapids Public Museum in the late 1950s. She was one of the founders of the Grand Rapids Amateur Astronomical Association. The names Alnitak, Alnilam and Mintaka have stuck with me ever since. It was through her that I was able to worm my way into working at the museum’s new then unnamed planetarium. I also remember being in her office with her, listening to the radio as Alan Shepard made his historic suborbital flight on May 5th, 1961.
Rigel is a hot blue-white star, and will probably become a red giant star like Betelgeuse. There is another bright star named Rigel, but most don’t know it. It’s Rigel Kentaurus, the leg of the centaur of Centaurus. It’s better known as Alpha Centauri, a catalog designation, and the nearest star to the solar system.
12/11/2017 – Ephemeris – Orion rising
Ephemeris for Monday, December 11th. The Sun will rise at 8:09. It’ll be up for 8 hours and 52 minutes, setting at 5:02. The Moon, 1 day past last quarter, will rise at 2:22 tomorrow morning.
Off in the east-southeast at 9 in the evening the great constellation of Orion will be seen. This is the most famous of all constellations world-wide. We think the Big Dipper is a big deal. It’s not even a constellation, being the hind end of the great bear Ursa Major. Also it’s invisible if one travels far enough south of the equator. Orion is now a rectangle of stars tilted to the left as he rises. With three stars in a straight line in the center, his belt. They are aligned nearly vertically. Orion is a giant hunter. The rectangle depicts his shoulders and knees. Among its other bright stars Orion contains two of the brightest. The upper left star is the famous red giant star Betelgeuse. The lower left star is the blue-white super giant Rigel.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addenda
Orion fully risen in the east-southeast a 9 p,m, approximately 4 hours after sunset, December 11. Created using Stellarium and GIMP.
Note to Blog readers
As you probably know these posts are transcripts of my Ephemeris program. The length of the program is exactly 59 seconds, and the first paragraph takes approximately 14 of those seconds. So I don’t have much time for the topic at hand. Therefore I dole out information in rather small spoonfuls. I’ll be revisiting Orion many times over the winter, talking about the other stars, and wonders found among its stars, also its mythology. If you can’t wait, type Orion in the search bar for all the past programs on Orion. Don’t be surprised that much of the programs don’t change much from year to year. I post the week’s worth of Ephemeris program MP3s on my monthly website http://ephemeris.bjmoler.org/ under the Audio link.
Sunday night and into the wee hours of Monday morning is the time I usually write and record the programs for Tuesday through the next Monday. Blog postings are prepared the night before the air date.
11/20/2017 – Ephemeris – The Moon is near Saturn tonight and the approaching signs of winter
Ephemeris for Monday, November 20th. The Sun will rise at 7:46. It’ll be up for 9 hours and 23 minutes, setting at 5:09. The Moon, 2 days past new, will set at 7:04 this evening.
Tonight the two day old Moon will appear near Saturn. The ringed planet will appear to the left and a bit below the thin crescent Moon before they set about an hour later. The approaching winter season and the resumption of standard time have dropped sunset to 5:09 in the Interlochen/Traverse City area. Our sunset will drop another 11 minutes before slowly recovering 19 days from now. Two to three hours later another sign of the approaching winter season will appear, as the constellation of the giant hunter Orion rises in the east. He is resplendent with his nearly vertical belt of three stars rising, framed to the left and right by the bright stars reddish Betelgeuse and bluish Rigel. He will dominate our evening skies until April.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Moon and Saturn at 6 p.m. November 20, 2017. Created using Stellarium.
Finder chart for the rising Orion at 9 p.m., November 30, 2017. Created using Stellarium and GIMP.
02/16/2017 – Ephemeris – The Winter Circle
Ephemeris for Thursday, February 16th. The Sun will rise at 7:40. It’ll be up for 10 hours and 32 minutes, setting at 6:12. The Moon, 2 days before last quarter, will rise at 12:17 tomorrow morning.
The winter skies are blessed with more first magnitude stars than any other season. These are the twenty-one brightest stars in the sky. Six of these stars lie in a large circle centered on the seventh. This circle is up all evening now that we are in the heart of winter. Starting high overhead is Capella in Auriga the charioteer. Moving clockwise, we come to Aldebaran in the face of Taurus the Bull. Then down to Orion’s knee we find Rigel. Down and left is the brightest star of all Sirius the Dog Star in Canis Major Orion’s large hunting dog, lowest of these stars in the south. Moving up and left there is Procyon in Canis Minor, Then above it is Pollux in Gemini the twins. All are centered on Betelgeuse in Orion.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Winter Circle of 1st magnitude stars. Created using my LookingUp program.
01/10/2017 – Ephemeris – Rigel, the blue super-giant in Orion
Ephemeris for Tuesday, January 10th. The Sun will rise at 8:17. It’ll be up for 9 hours and 4 minutes, setting at 5:22. The Moon, 2 days before full, will set at 7:10 tomorrow morning.
Yesterday I talked about the star Betelgeuse the bright red star in the top left of Orion’s upright rectangle. Orion is seen in the southeast at 9 in the evening. The blue-white star in Orion’s opposite corner is usually brighter. It is Rigel whose longer Arabic name of which Rigel is the first part means Left Leg of the Giant. Rigel is a giant itself, actually a super giant star, which is more a measure of its mass than its size, that of 23 solar masses. Its surface temperature is twice as hot as the Sun. It is 120 thousand times as bright as the sun and 79 times its diameter. Its distance is around 860 light years. Those with telescopes might be able to spot a close companion star to Rigel, just at the edge of the bright arc light image of Rigel itself.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The named stars of Orion. Created using Stellarium.
Rigel with its companion star as photographed through a telescope. No attribution. The source website no longer exists.
