Archive
06/22/2017 – Ephemeris – Now that it’s summer, lets check out the Summer Triangle
Ephemeris for Thursday, June 22nd. Today the Sun will be up for 15 hours and 33 minutes, setting at 9:31, and it will rise tomorrow at 5:57. The Moon, 1 day before new, will rise at 5:45 tomorrow morning.
We’re a day into summer, and the asterism or informal constellation called the Summer Triangle can be seen rising in the east as it gets dark. Highest of the three bright stars is Vega in the constellation Lyra the harp, whose body is seen in a narrow parallelogram nearby. The second star of the triangle is Deneb lower and left of Vega, It appears dimmer than Vega because it is by far the most distant of the three. The third star of the Summer Triangle is seen farther below and a right of Vega. It is Altair in Aquila the eagle, and the closest. Altair is 16.5 light years away, Vega is 27 light years while Deneb may be a whopping 2600 light years away. One light year is 6 trillion miles (9 trillion km).
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The Summer Triangle. Created using Stellarium and The Gimp.
06/13/2017 – Ephemeris – I call Antares the UFO star
Ephemeris for Tuesday, June 13th. Today the Sun will be up for 15 hours and 31 minutes, setting at 9:28, and it will rise tomorrow at 5:56. The Moon, half way from full to last quarter, will rise at 12:22 tomorrow morning.
Last week I was observing and showing another person the sky when she remarked about that star low in the sky. That star happened to be Antares, which I call the UFO star. This is a red giant star which in Interlochen and Traverse City never rises above 19 degrees over the southern horizon. It is located in the heart of the constellation Scorpius the Scorpion. With the turbulence in the Earth’s atmosphere, being more marked for objects low in the sky, Antares twinkles mightily. And also being low in the sky, the atmosphere also breaks Antares’ light into a rainbow of colors which, under binocular and telescopic magnification can give the appearance of a multicolored sparkler.
The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The star Antares in the heart of Scorpius and the planets Saturn and Jupiter at 11 p.m., June 1, 2017. Created using Stellarium.
The star Antares in long exposure in this image probably taken from farther south than here. Source unknown, however because the star has four diffraction spikes the photograph was taken with a reflector telescope whose secondary mirror is supported by a 4 vane “spider”.
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.
02/13/2017 – Ephemeris – The brightest night-time star has a tiny stellar companion
Ephemeris for Monday, February 13th. The Sun will rise at 7:45. It’ll be up for 10 hours and 23 minutes, setting at 6:08. The Moon, 3 days past full, will rise at 9:16 this evening.
Sirius is the brightest night-time star and is located in the south at 9 p.m. below and a bit left of Orion the Hunter. We’ve visited Sirius last week. But there is another star in the Sirius system that is practically invisible due to Sirius’ dazzling glare. It’s Sirius B, nicknamed the Pup, alluding to Sirius’ Dog Star title. The tiny star was suspected as far back as 1834 due to Sirius’ wavy path in the sky against the more distant stars. Sirius is only 8 light years away. Sirius A and the Pup have 50 year orbits of each other. The star was first seen by Alvan Clark in 1862 while testing a new telescope. The Pup was the first of a new class of stars to be discovered, white dwarfs. The Pup is about the size of the Earth, with the mass of our Sun; its out of fuel and slowly collapsing.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Sirius A & B’s path in the sky showing the wobble that betrayed the Pup’s presence. Credit Mike Guidry, University of Tennessee.
Sirius A and B (near the diffraction spike to the lower left), A Hubble Space Telescope photograph. Credit NASA, ESA.
Orion’s Belt points to Sirius. Created using Stellarium.
02/07/2017 – Ephemeris – Sirius: an important star in history
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
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?
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
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.
01/10/2017 – 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.
01/09/2017 – Ephemeris – Betelgeuse the bright red star in Orion
Ephemeris for Monday, January 9th. The Sun will rise at 8:18. It’ll be up for 9 hours and 3 minutes, setting at 5:21. The Moon, 3 days before full, will set at 6:06 tomorrow morning.
The bright red star in constellation Orion’s shoulder is Betelgeuse, 643 light years away give or take 146 light years. Betelgeuse is a shortened form of an Arabic phrase that means “Armpit of the central one”. Orion is seen in the south in the evening. Even at its great distance it’s the star whose surface is easiest seen, after the sun of course. That’s because it’s so big. Possibly larger around than the orbit of Jupiter, though that’s hard to determine. Recent telescopic observations of Betelgeuse have shown shells of gas surrounding the star. A star like Betelgeuse is so bloated that it can be described as a red-hot vacuum, thus its edge or limb is much darker than its center. The sun has limb darkening too, but it is much less noticeable.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Orion upright and due south. Created using Stellarium.
Betelgeuse and its nebula. From European Southern Observatory’s Very Large Telescope.
Betelgeuse is a single star like the Sun there is evidence that Betelgeuse may have eaten its companion star 100,000 years ago, yum! http://phys.org/news/2016-12-famous-red-star-betelgeuse-faster.html
12/08/2016 – Ephemeris – Aldebaran, the follower
Ephemeris for Thursday, December 8th. The Sun will rise at 8:07. It’ll be up for 8 hours and 54 minutes, setting at 5:02. The Moon, 1 day past first quarter, will set at 2:26 tomorrow morning.
The central constellation of winter, Orion, is low in the east-southeast at 9 p.m. Above it is Taurus the bull. The bright orange star in Taurus is Aldebaran. Aldebaran appears at the bottom left tip of a letter V group of stars lying on its side that is the face of the bull. Aldebaran isn’t actually part of the group, called the Hyades star cluster. The cluster is about 151 light years away, while Aldebaran is a bit less than half that. 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 350 times brighter than the Sun. Next Monday night the 12th, the Moon will pass in front of Aldebaran in an event called an occultation I’ll have more information on it then. The name Aldebaran means The Follower, since it follows the Pleiades across the sky as the Earth rotates.
Times 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.
12/06/2016 – Ephemeris – Capella the northernmost first magnitude star
Ephemeris for Tuesday, December 6th. The Sun will rise at 8:05. It’ll be up for 8 hours and 56 minutes, setting at 5:02. The Moon, 1 day before first quarter, will set at 12:08 tomorrow morning.
A bright star called Capella has slowly been rising in the northeastern sky in the evenings for the past few months. At 8 p.m. now it is low in the east-northeast to the upper left of Orion, rising in the east. This winter Capella will be overhead, the highest of winter’s seven brilliant first magnitude stars. Capella never quite sets for anyone north of Ludington. Due to its brightness, and being the closest first magnitude star to the pole, Capella appears to move slowly as the earth rotates, and spends summer and autumn evenings close to the horizon, and has, in years past, elicited a few phone calls and other queries about that ‘bright object in the northeast’. Capella belongs to the pentagonal constellation of Auriga the charioteer.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
The star Capella with the other stars and constellations of Winter rising in the east. Created using Stellarium.
Bob Moler's Ephemeris Blog 