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Posts Tagged ‘Sirius’

02/16/2017 – Ephemeris – The Winter Circle

February 16, 2017 Comments off

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

The Winter Circle of 1st magnitude stars. Created using my LookingUp program.

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02/07/2017 – Ephemeris – Sirius: an important star in history

February 7, 2017 Comments off

Ephemeris for Tuesday, February 7th.  The Sun will rise at 7:53.  It’ll be up for 10 hours and 6 minutes, setting at 6:00.  The Moon, 3 days before full, will set at 5:53 tomorrow morning.

The brightest star-like object in the evening sky is Sirius, also known as the Dog Star.  It also is the brightest night-time star in our skies period.  Tonight at 9 p.m. it’s located in the southeastern sky.  The Dog Star name comes from its position at the heart of the constellation Canis Major, the great dog of Orion the hunter.  The three stars of Orion’s belt tilt to the southeast and point to Sirius.  The name Sirius means ‘Dazzling One’, a reference to its great brilliance and twinkling.  Its Egyptian name was Sothis, and its appearance in the dawn skies in late June signaled the flooding of the Nile, and the beginning of the Egyptian agricultural year.  Sirius owes much of its brightness to the fact that it lies quite close to us, only about 8 light years away.

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

Addendum

Heliacal rising of Sirius

A simulation of the heliacal rising of Sothis (Sirius) with the Egyptian Pyramids circa 2000 BC.  Note that Sirius is just visible to the right of the nearest Pyramid. Created using Stellarium and GIMP.

A heliacal rising is the first appearance of a star or planet in the morning after disappearing weeks or months before in the evening twilight.

01/26/2017 – Ephemeris – Is it a dachshund or a hot dog?

January 26, 2017 Comments off

Ephemeris for Thursday, January 26th.  The Sun will rise at 8:07.  It’ll be up for 9 hours and 36 minutes, setting at 5:43.  The Moon, 1 day before new, will rise at 7:40 tomorrow morning.

The constellation Orion has two hunting dogs.  We’ve seen Canis Major the greater dog at Orion’s feet with Sirius in its heart.  The lesser dog, Canis Minor is level with Betelgeuse in Orion’s shoulder and off to the left.  Just two stars mark it.  Is it a dachshund or is it a hot dog?  You decide.  It’s brighter star’s name is Procyon which means “Before the dog”, an odd title.  It means that though east of Sirius, it rises before Sirius, due to its more northerly position in the sky.  In many ways Procyon is nearly a twin of Sirius.  It shines with the same white color, although a bit cooler, and has a white dwarf companion like Sirius.  It’s a bit farther away than Sirius’ 8 light years.  Procyon is 11 and a half light years away.  Procyon, Betelgeuse and Sirius make the winter triangle.

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

Addendum

Orion and hunting dogs

Procyon and Orion’s hunting dogs animation also showing the Winter Triangle asterism*. Created using Stellarium and GIMP.

* Asterism – an informal constellation like the Big Dipper, the Northern Cross, or the Summer Triangle.  Not one of the 88 official constellations.

01/20/2017 – Ephemeris – Orion’s greater hunting dog

January 20, 2017 Comments off

Ephemeris for Friday, January 20th.  The Sun will rise at 8:12.  It’ll be up for 9 hours and 22 minutes, setting at 5:35.  The Moon, 1 day past last quarter, will rise at 2:29 tomorrow morning.

The great winter constellation or star group Orion the Hunter, is located in the south-southeastern sky at 9 p.m.  His elongated rectangle of a torso is almost 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.  There lies the  brilliant star called Sirius, 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.  I’ll have more to say about Sirius in the future, but there’s a fine star cluster, called M41, at the 5 o’clock position from Sirius easily visible in binoculars or a small telescope.

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

Addendum

Orion and Canis Major

Orion and Canis Major Animation for 9 p.m. January 20, 2017. Click on image to enlarge.  Created using Stellarium and GIMP.

 

12/27/2016 – Ephemeris – The stars of Orion

December 27, 2016 2 comments

Ephemeris for Tuesday, December 27th.  The Sun will rise at 8:19.  It’ll be up for 8 hours and 49 minutes, setting at 5:09.  The Moon, 2 days before new, will rise at 7:26 tomorrow morning.

The large and bright constellation of Orion the hunter is in the southeast at 9 p.m., with the bright star Sirius below it near the horizon.  The equally spaced line of three stars of Orion’s belt are nearly vertical and point down to Sirius, also known as the Dog Star in Canis Major, Orion’s greater dog.  The whole of its constellation stars aren’t up at 9 p.m., but they will all clear the horizon by 10 p.m.   Those three belt stars are in the center of an elongated rectangle of stars  At the top left of Orion’s shoulder stars is the red giant star Betelgeuse.  The right shoulder star is Bellatrix.  Both Bellatrix and Sirius along with the names of other stars and constellations should be familiar to fans of the Harry Potter novels and movies, as members of the house of Black.  The knee stars at the bottom of the rectangle are, from left to right Saiph and the brilliant blue giant star Rigel.  Between his belt and knees are stars of his sword.

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

Addendum

Orion

Orion, star names, and constellation art animation position for 9 p.m. December 27. Created using Stellarium and GIMP. Artist: Johan Meuris.

In the image above I’ve added the belt star names, though they are generally covered in a program of their own.

02/16/2015 – Ephemeris – The little Dog Star

February 16, 2016 Comments off

Ephemeris for Tuesday, February 16th.  The Sun will rise at 7:42.  It’ll be up for 10 hours and 29 minutes, setting at 6:12.   The Moon, 1 day past first quarter, will set at 3:45 tomorrow morning.

Procyon is  the bright star to the east or left of Betelgeuse in the sky tonight, which puts it in the east-southeast at 9 tonight.  Procyon is the brightest of the two stars in Canis Minor, Orion’s little hunting dog.  Procyon is sometimes called the Little Dog Star for that reason.  The Dog Star Sirius is a ways below and right of it.  The name Procyon means “Before the Dog”, because Procyon, though east of Sirius, rises before it due to its more northerly position.  This only works if one is north of 30 degrees north latitude.  South of that, Sirius rises first.  Procyon is a white star 11 and a half light years away, 3 light years farther than Sirius, and like Sirius it has a faint white dwarf companion.  It’s a bit less than half the Sun’s age.

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

Addendum

Procyon, Sirius and the stars of winter. Created using Stellarium

Procyon, Sirius and the stars of winter. Created using Stellarium

Note that at their rising Procyon is higher in the sky than Sirius.

There are some grid lines on the chart.  The ones running from lower left to upper right are lines of declination, which are like latitude lines on the Earth.  On this chart they are 10º apart.  The line that intersects the horizon at the east compass point is the celestial equator.  It will meet the western compass point at the horizon.  As the Earth rotates the stars and planets will move westward in the direction of these declination lines.  The lines that run from upper left to lower right are hour lines of right ascension.  Here they are 15 degrees or one hour apart,  The Earth rotates 360º in a sidereal* day.  360 divided by 24 hours gives 15º an hour.  So the celestial sphere of stars and planets will slide 15º westward in a sidereal hour.

*  A sidereal day, rotation with respect to the stars, is about 4 minutes shorter that the solar day, the day and time we keep based on the Sun.  The Sun moves about one degree eastward each day, so the rotation has to catch up that one degree each day.  The rotation of one degree takes 4 minutes.  I’ll let you work that one out for yourself.

02/12/2016 – Ephemeris – A circle of bright stars in winter

February 12, 2016 Comments off

Ephemeris for Friday, February 12th.  The Sun will rise at 7:48.  It’ll be up for 10 hours and 18 minutes, setting at 6:06.   The Moon, 3 days before first quarter, will set at 11:19 this evening.

The winter skies are blessed with more first magnitude stars than any other season.  With the moon out these stars will stand out even more, as dimmer stars are suppressed.  Six of these stars lie in a large circle centered on the seventh, the Winter Circle.

This circle is up at 9 p.m.  Starting high nearly overhead is Capella in Auriga the charioteer.  Moving clockwise down to the south, 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 in Canis Major Orion’s large hunting dog, lowest of these stars in the southeast.  Moving up and left there is Procyon in Canis Minor,  Above is Pollux in Gemini the twins.  All are centered on Betelgeuse the bright red star in Orion’s shoulder.

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

Addendum

Winter Circle

The bright stars of winter arrayed in a circle. Created using Stellarium.

Some also see a Winter Triangle consisting of the stars Betelgeuse, Sirius and Procyon.