02/10/2023 – Ephemeris – Finding Orion’s greater hunting dog, Canis Major

This is Bob Moler with Ephemeris for Friday, February 10th. Today the Sun will be up for 10 hours and 13 minutes, setting at 6:04, and it will rise tomorrow at 7:49. The Moon, 3 days before last quarter, will rise at 11:14 this evening.

The great winter constellation or star group, Orion the hunter, is located in the southern sky at 9 p.m. His elongated rectangle of a torso is 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. They point to Sirius, the brightest nighttime star, 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. There’s a fine star cluster, called Messier, or M 41, at the 5 o’clock position from Sirius. It’s easily visible in binoculars or a small telescope.

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

Orion and Canis Major animation for earlier than 9 in the evening. Created using Stellarium and GIMP.

01/05/2023 – Ephemeris – I’m Sirius about this being the brightest nighttime star!

Jan 5. This is Bob Moler with Ephemeris for Thursday, January 5th. Today the Sun will be up for 8 hours and 56 minutes, setting at 5:16, and it will rise tomorrow at 8:19. The Moon, 1 day before full, will set at 8:33 tomorrow morning.

The brightest nighttime star, Sirius, rises before 8 pm tonight. It can be found by following the constellation Orion’s three belt stars downward to near the east-southeastern horizon. As far as star-like objects go, Jupiter and Venus can always outshine Sirius. Mars can too, but only when it is near the Earth and this early evening when Mars is high in the sky and Sirius is low in the sky. When the Moon clears out of the evening sky, and Sirius rises higher, the other stars of its constellation will become visible. That constellation is Canis Major, Orion’s great hunting dog, from which it gets its nickname: Dog Star. The name Sirius means Dazzling One, an allusion to its great brightness and, being low in the sky, it twinkles mightily.

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

A Sirius finder animation for January/early February at around 8 pm. Even in bright moonlight, the seven bright stars of Orion can be seen. The three stars of Orion’s belt make a great pointer to Sirius. Created using Stellarium, GIMP and LibreOffice (for the arrow).

02/28/2022 – Ephemeris – Ancient Egypt’s most important star

This is Ephemeris for Monday, February 28th. Today the Sun will be up for 11 hours and 7 minutes, setting at 6:29, and it will rise tomorrow at 7:20. The Moon, 2 days before new, will rise at 7:17 tomorrow morning.

The Ancient Egyptian agricultural year began with the flooding of the Nile, which was announced by the heliacal rising of the brightest nighttime star, Sirius. A heliacal rising is the first appearance of a star in the morning twilight after disappearing in evening twilight some months before. The Greeks called the star Sothis, while the ancient Egyptians called the star Sopdet. The heliacal rising would occur on July 20th had our calendar been in use back then. The relationship between the summer solstice and the heliacal rising of Sothis, 29 days later, stayed the same for nearly three millennia, from at least 2900 BCE to 12 CE, despite precession* of the Earth’s axis moving the Sun from the middle of the constellation Leo at the summer solstice to the western edge of Cancer one and a half constellations west. Sopdet was personified by a goddess, who was the consort to Sah, who is what they called Orion.

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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.

* Precession of the equinoxes. The slow, 26,000 year wobble of the Earth’s axis which causes the Earth, most of the time, to not have a pole star. We’re lucky to live at a time to have a bright star within a degree of the north celestial pole. That star is, of course, Polaris. Precession also changes the point in the sky, along the ecliptic and zodiac, where the Sun appears on the first day of spring, or any season. These points move westward along the ecliptic (the plane of the earth’s orbit of the Sun) one degree every 72 years.

Addendum

The Egyptian used the heliacal rising of Sirius as a signal that the flooding of the Nile was imminent, starting their agricultural year. The Greeks called the star Sothis, while the Egyptians themselves called it Sopdet, a goddess, and consort of the god Sah, our Orion.
Part of my presentation, December 2021 of Ancient Astronomy of the Egyptians and Babylonians.

02/25/2022 – Ephemeris – The star that’s called the Pup

This is Ephemeris for Friday, February 25th. Today the Sun will be up for 10 hours and 58 minutes, setting at 6:25, and it will rise tomorrow at 7:25. The Moon, 2 days past last quarter, will rise at 5:04 tomorrow morning.

Sirius is the brightest nighttime 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 Friday. But there is another star in the Sirius system that is practically invisible due to Sirius’ dazzling glare. Its name is Sirius B, nicknamed the Pup, alluding to Sirius’ Dog Star title as the heart of Canis Major, Orion’s larger hunting dog. The tiny star was suspected as far back as 1834 due to Sirius’ wavy path in the sky against the more distant stars. Sirius and the Pup have 50-year orbits of each other. The Pup was first seen by famed 19th century telescope maker 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, with the mass of the Sun, is packed into the volume of the Earth.

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

A Sirius finder animation for late January/early February at around 8 pm. Even in bright moonlight, the seven bright stars of Orion can be seen. The three stars of Orion’s belt make a great pointer to Sirius. Created using Stellarium, GIMP and Libreoffice (for the arrow).

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 imaged by two different space telescopes, revealing dramatically different views! Hubble’s image (left) shows Sirius A shining brightly in visible light, with diminutive Sirius B a tiny dot. However, in Chandra’s image (right) tiny Sirius B is dramatically brighter in X-rays! The “Universe in a Different Light” activity highlights more surprising views of some familiar objects: http://bit.ly/different-light-nsn NASA, ESA, H. Bond (STScI), and M. Barstow (University of Leicester) (left); NASA/SAO/CXC (right)

02/22/2022 – Ephemeris – The Winter Triangle

This is Ephemeris for Tuesday, February 22nd. Today the Sun will be up for 10 hours and 49 minutes, setting at 6:21, and it will rise tomorrow at 7:30. The Moon, 1 day before last quarter, will rise at 1:26 tomorrow morning.

I’ve talked about the Winter Circle of bright stars already this winter, but some other astronomers talk about the Winter Triangle. The stars involved are Betelgeuse in the hunter Orion, Sirius in Canis Major, Orion’s large hunting dog, and Procyon in Canis Minor, his other small hunting dog. These three stars enclose a rather blank piece of sky with the faint Milky Way running through it and the almost invisible constellation of Monoceros the unicorn. The Summer Triangle has three bright stars with no other close competition. The Winter Triangle has four other bright stars near it. Any three of these would make a nice triangle. One of these constellations, Canis Minor, is tiny with Procyon and one other star. It makes me think of a dachshund, or maybe, if I’m hungry, a hot dog.

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 Winter Triangle. It encloses a pretty blank space where Monoceros the unicorn lies. Created using Stellarium with my annotations for the Winter Triangle.

02/18/2022 – Ephemeris – Sirius, the brightest nighttime star

This is Ephemeris for Friday, February 18th. Today the Sun will be up for 10 hours and 37 minutes, setting at 6:15, and it will rise tomorrow at 7:36. The Moon, 2 days past full, will rise at 8:32 this evening.

In the evening, the great constellation of Orion the hunter can be seen in the south. Its large rectangle of bright stars is easily visible, even with a full moon. The three stars in a straight line, his belt, tilt downward to the left to a very bright star merrily twinkling lower in the sky. This star is called Sirius, also known as the Dog Star because it’s in the heart of Orion’s larger hunting dog, Canis Major. It is an arc light white star as seen in binoculars or telescope. It is the brightest star in the night sky, and a neighboring star, just twice the distance of the closest star to the Sun at 8.6 light years. It’s name, Sirius, has nothing to do with a dog, but is from the Greek meaning scorching for its brightness or sparkling, due to its intense twinkling.

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

In the southern sky, Orion’s belt points to Sirius. Created using Stellarium, Libreoffice and GIMP.

01/31/2022 – Ephemeris – The winter circle of bright stars

This is Ephemeris for Monday, January 31st. Today the Sun will be up for 9 hours and 47 minutes, setting at 5:50, and it will rise tomorrow at 8:01. The Moon, 1 day before new, will rise at 8:48 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 in the evening. 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 not quite centered on Betelgeuse, the bright red star in Orion’s shoulder.

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 bright stars of winter arrayed in a not so accurate circle. Some call it the Winter Hexagon. These stars are what make the winter sky so brilliant on the rare clear night in winter. Created using Stellarium.

03/02/2021 – Ephemeris – Sirius and the Pup

This is Ephemeris for Tuesday, March 2nd. Today the Sun will be up for 11 hours and 14 minutes, setting at 6:32, and it will rise tomorrow at 7:16. The Moon, halfway from full to last quarter, will rise at 10:51 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 a month ago. But there is another star in the Sirius system that is practically invisible due to Sirius’ dazzling glare. Its name is 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 against the more distant stars in the sky. Sirius and the Pup have 50-year orbits of each other. The Pup was first seen in 1862. It was the first of a new class of stars to be discovered, white dwarfs. The Pup is a dying star with the mass of the Sun, collapsed down to the size of the Earth after running out of hydrogen fuel in its core.

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

Addendum

A Sirius finder animation for late January/early February at around 8 pm. Even in bright moonlight the seven bright stars of Orion can be seen. The three stars of Orion’s belt make a great pointer to Sirius. Created using Stellarium, GIMP and Libreoffice (for the arrow).

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 imaged by two different space telescopes, revealing dramatically different views! Hubble’s image (left) shows Sirius A shining brightly in visible light, with diminutive Sirius B a tiny dot. However, in Chandra’s image (right) tiny Sirius B is dramatically brighter in X-rays! The “Universe in a Different Light” activity highlights more surprising views of some familiar objects: http://bit.ly/different-light-nsn NASA, ESA, H. Bond (STScI), and M. Barstow (University of Leicester) (left); NASA/SAO/CXC (right).

 

 

02/11/2021 – Ephemeris – The Winter Triangle

This is Ephemeris for Thursday, February 11th. Today the Sun will be up for 10 hours and 17 minutes, setting at 6:06, and it will rise tomorrow at 7:47. The Moon is new today, and won’t be visible.

I usually talk about the Winter Circle of bright stars, but some other astronomers talk about the Winter Triangle. The stars involved are Betelgeuse in the hunter Orion, Sirius in Canis Major, Orion’s large hunting dog, and Procyon in Canis Minor, his other small hunting dog. These three stars enclose a rather blank piece of sky with the faint Milky Way running through it and the almost invisible constellation of Monoceros the unicorn. The Summer Triangle has three bright stars with no other close competition. The Winter Triangle has four other bright stars near it. Any three of these would make a nice triangle. One of these constellations Canis Minor is tiny, with Procyon and one other star. It makes me think of a dachshund, or maybe, if I’m hungry, a hot dog.

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

Addendum

Winter Triangle finder animation. It shows the star field, named first magnitude stars, then their constellations, then the Winter Triangle and constellations of the three stars. Click on the image to enlarge. Created using Stellarium and GIMP.

01/29/2021 – Ephemeris – Let’s get Sirius

This is Ephemeris for Friday, January 29th. Today the Sun will be up for 9 hours and 42 minutes, setting at 5:47, and it will rise tomorrow at 8:03. The Moon, 1 day past full, will rise at 6:49 this evening.

In the early evening the great constellation of Orion the hunter can be seen in the southeast. Its large rectangle of bright stars is easily visible, even with a full moon. The three stars in a straight line, his belt, tilt downward to the left to a very bright star merrily twinkling lower in the sky. This star is called Sirius, also known as the Dog Star because it’s in the heart of Orion’s larger hunting dog, Canis Major. It is an arc light white star as seen in binoculars or telescope. It is the brightest star in the night sky, and a neighboring star, just twice the distance of the closest star to the Sun at 8.6 light years. It’s name, Sirius, has nothing to do with a dog, but is from the Greek meaning scorching for its brightness or sparkling, due to its intense twinkling.

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

Addendum

A Sirius finder animation for late January/early February at around 8 pm. Even in bright moonlight the seven bright stars of Orion can be seen. The three stars of Orion’s belt make a great pointer to Sirius. Created using Stellarium, GIMP and Libreoffice (for the arrow).

I’ll come back to Sirius several times this winter. Or search for Sirius for other times I’ve talked about this brightest of the night-time stars.