The Return of the Dog Days

Once again, we enter the Dog Days of summer. These 40 days of especially hot and humid weather often have little rainfall, but here in the Paradelle Northeast of the U.S. we have been getting a lot of rain with our 90+ degree days and humidity.

The ancient Greeks believed that Sirius, the “dog star” was rising with the Sun at this time was adding to the Sun’s heat. After all, since Sirius is the brightest star in the sky, they assumed it would be a second Sun and give off heat like our nearest star.

Sirius is called the Dog Star because it’s part of the constellation Canis Major (Greater Dog).  Sirius means sparkling or scorching which is certainly what it seemed like to early astronomers. Sirius is almost twice as bright as Canopus, the next brightest star.

Those ancients also believed that the weather made dogs go mad. The Romans unfortunately tried to appease Sirius by sacrificing a brown dog at the start of the Dog Days.

Ancient Egyptians saw this time of Sirius arriving with the Sun as the beginning of the Nile’s flooding season. It was also their time for New Year celebrations.

“Dog Days” has become in modern times a term for any period of stagnation or inactivity. Wall Street marks this period as a generally slow and sluggish time for the markets (though earnings do create some heat).

via Etsy

A Star to Mark a New Year

Sirius (bottom) and the constellation Orion (right) with its 3-star “belt.”                        (Hubble European Space Agency Image by Akira Fujii – spacetelescope.org)

Sirius is the brightest star in the sky.  Its common name is the Dog Star because it’s part of the constellation Canis Major (Greater Dog). “Sirius” means sparkling or scorching – a name given for its brightness in the night sky.  Sirius is almost twice as bright as Canopus, the next brightest star.

It reaches its highest point in the sky around the stroke of midnight every year and so tonight we can think of it as the New Year’s Star. Astronomers call this a midnight culmination of Sirius. What a cosmically strange coincidence it is that as we ring in the New Year, Sirius peaks in the sky. Is it a coincidence?

To find Sirius, I look North in Paradelle but at midnight I’m really looking up above. You should be able to find Orion’s three belt stars. Follow the belt’s line down to the left (west) and there is bright Sirius.

Like the sun, the stars rise in the east and travel westward across the sky.  Midway between rising and setting, the sun or any star reaches its highest point in the sky. Tonight, for Sirius, it will be at midnight.

At a distance of 2.64 parsecs (Yes, that’s a real thing), the Sirius system is one of Earth’s nearest neighbors. Sirius is gradually moving closer to our Solar System, so it will slightly increase in brightness over the next 60,000 years and then the distance will increase, and it will become fainter. Even then, astronomers say that it will still be the brightest star in the Earth’s night sky for the next 210,000 years.

A bust of Sopdet, the Egyptian goddess of Sirius

The heliacal rising of a star occurs annually when it briefly becomes visible above the eastern horizon at dawn just before sunrise after it has spent a season behind the sun rendering it invisible. Historically, the most important such rising is that of Sirius.

It was an important feature of the Egyptian calendar and marked the flooding of the Nile in Ancient Egypt. The ancient Egyptians worshipped the star as the goddess Sopdet, the guarantor of the fertility of their land. The Egyptian civil calendar was apparently initiated to have the New Year “Mesori” coincide with the appearance of Sirius.

Sirius (Spdt) in hieroglyphs

The rising meant the “dog days” of summer for the ancient Greeks. To the Polynesians, mostly in the Southern Hemisphere, the star’s rise marked winter and was an important reference for their navigation around the Pacific Ocean.

All hail, Sirius!

Watching the Mid-night Culmination of Sirius on New Year’s Eve

Image via Oliver Jeffers

On this New Year’s Eve, I will look up to the night sky to the brightest star there. That is Sirius, in the constellation Canis Major. You can see it in the evening every year at this time from almost all parts of Earth. Tonight is not only the calendar end of year but, in one of those nice celestial coincidences, it is the midnight culmination of Sirius. That is when it is highest in the sky at midnight, which occurs only once every year.

I need to point out that this midnight is mid-night and not the drop-the-ball midnight we will celebrate tonight. What I will call mid-night is the actual middle of the night, which is midway between sunset and sunrise. For my little piece of Paradelle, that will be at 9:18 pm ET.

If you go to http://aa.usno.navy.mil/data/docs/mrst.php you can get a quick calculation done for your little place on Earth for the times of the rise, set, and transit for the Sun and all major solar system bodies and selected bright stars.

From the Northern Hemisphere, we will look toward the south to see Sirius shining brightly on a clear night. (From the Southern Hemisphere, look overhead or high in the north.)

Sirius, the Dog Star, gets its name from a romanization of the Greek Seirios, meaning “glowing” or “scorching.” It appears almost twice as bright as the next brightest star (Canopus). Sirius appears bright because of its “intrinsic luminosity” and also because of its proximity to Earth.  It is 2.6 parsecs away. I know that sounds like Star Trek talk, but the Sirius system is one of Earth’s near neighbours. Sirius is gradually moving closer to the Solar System, so it will slightly increase in brightness over the next 60,000 years. After that time, its distance will begin to increase and it will become fainter. But Sirius doesn’t have to worry about losing its brightest star ranking for 210,000 years.

What we see is a bit of an illusion because “Sirius” is a binary star system, consisting of a white main-sequence star, called Sirius A, and a faint white dwarf companion of called Sirius B. Sirius A is about twice as massive as the Sun and 25 times more luminous than the Sun. Sirius B was actually bigger but consumed its resources and became a red giant. Then, it shed its outer layers and collapsed into its current state as a white dwarf. That happened around 120 million years ago.

All this makes me feel both very tiny, and also part of something so large that I cannot really comprehend it all. So, I will simply go out tonight on this very cold night and look up at Sirius with great wonder.

 

“The most beautiful thing we can experience is the mysterious. It is the source of all true art and science. He to whom the emotion is a stranger, who can no longer pause to wonder and stand wrapped in awe, is as good as dead —his eyes are closed. The insight into the mystery of life, coupled though it be with fear, has also given rise to religion. To know what is impenetrable to us really exists, manifesting itself as the highest wisdom and the most radiant beauty, which our dull faculties can comprehend only in their most primitive forms—this knowledge, this feeling is at the center of true religiousness.”
― Albert Einstein, Ideas and Opinions

Welcome to the Dog Days

Summer is less than a month old, but today is the beginning of the Dog Days of summer.

Those days run for 40 days and are generally known as especially hot and humid weather with little rainfall. It’s the kind of weather that makes us feel a bit sluggish. It’s a time when we might want to have  bit of a dog’s life and just finding a nice shady spot to take a nap.

It was the ancient Greeks that gave it that tag because they believed that Sirius, the “dog star,” was making the sun hotter.  That quite visible star rises now with the sun and they assumed it was like a second sun.

The ancients also thought this was a period when dogs were more likely to go mad and have fits. Unfortunately, the Romans tried to appease Sirius by sacrificing a brown dog at the start of the Dog Days.

Nowadays, “Dog Days” is less of a weather term and more of a general term meaning any period of stagnation or inactivity. For example Wall Street marks this period as one that tends to be slow and sluggish.

Sirius White and Black

This is about two Sirius topics. Not so serious and not very well connected, except for the name.

Sirius is the brightest star in the nighttime sky tonight and most of the winter. (Venus and Jupiter outshine Sirius this month but I’m not considering planets.) And Sirius is easy to find in that sky full of stars.  Almost everyone can find Orion’s belt of three stars (if that is no longer true, please don’t tell me. It would depress me immensely.), and if you follow the imaginary line of that belt of medium-bright stars in Orion’s Belt, you will arrive at this bright white Sirius.

That other Sirius is Sirius Black,  a pure-blood wizard in the wizarding world of Harry Potter. He is the older son of Orion (Aha! A star connection!) and Walburga Black (from Saint Walpurga and that Walpurgis Night of witches?) , and the brother of Regulus (also named for a bright star).

Sirius parted ways with the Black family and their belief in blood purity. He was sorted into Gryffindor instead of Slytherin at Hogwarts.  According to the harrypotter.wikia.com, he attended that school from 1971 to 1978, which coincides with my own college years.

I like Sirius. My favorite line of his is probably when he tells Harry “We’ve all got both light and dark inside us. What matters is the part we choose to act on. That’s who we really are.”  I agree and I would certainly have joined the Order of the Phoenix with him, Harry’s father, James, and Lupin. (I would have had my doubts about letting Pettigrew join.) I would have been happy to be a Marauder against Voldemort.

Sirius is Harry’s godfather – a title some might find odd for families of wizards.

There are brighter stars than Sirius in absolute magnitude, but they are much farther away. Sirius is in the constellation Canis Major (the Greater Dog) and appears very bright because it is only 8.6 light-years away. Right in that constellation, Aludra and Omicron 2 are probably brighter but are also about 3,000 light-years away.

Sirius Black is an Animagus – a wizard who has learned to morph into an animal at will. Sirius becomes a massive black dog, like his brother star in Canis (dog) Major.

The August Dog Day’s Moon

Last year, there were two full Moons in August, so the second was a “Blue Moon.” That’s not true this year.

There are many names for this month’s Moon and usually I like to choose a different one each year. It could be the Grain Moon, Green Corn Moon, Red Moon (for the reddish hue it often takes on in the summer haze), Mating Moon, Woodcutter’s Moon, Chokeberry Moon, Summertime Moon, Corn Moon, Barley Moon, Dispute Moon, or the Moon When Cherries Turn Black.

I decided to go with the Dog Day’s Moon which refers to the phrase “dog days” a fairly common name for the sultry days of later summer. In the Northern Hemisphere, the dog days of summer are in July and August. In the Southern Hemisphere, they typically occur in January and February, in the midst of the austral summer.

Canis Major constellation map (Photo credit: Wikipedia)

This name goes back to the ancient Romans who tagged the diēs caniculārēs (dog days) as those hot days that occur along with the star Sirius. Sirius was known as the “Dog Star” because it is the brightest star in the constellation Canis Major (Large Dog). Sirius is also the brightest star in the night sky. The term “Dog Days” was used even earlier by the Greeks.

The Dog Days originally were the days when Sirius rose just before or at the same time as sunrise (heliacal rising), which is no longer true, owing to precession of the equinoxes. In Ancient Rome, the Dog Days ran from July 23/24 through August 23/24.

The Romans sacrificed a red dog in April to appease Sirius, believing that the star was the cause of the sultry weather. Dog Days were popularly believed to be an evil time “the Sea boiled, the Wine turned sour, Dogs grew mad, and all other creatures became languid; causing to man, among other diseases, burning fevers, hysterics, and phrensies.” according to Brady’s Clavis Calendaria (1813).

The ancient Greeks observed that the appearance of Sirius heralded the hot and dry summer, and feared that it caused plants to wilt, men to weaken, and women to become aroused.Due to its brightness, Sirius would have been noted to twinkle more in the unsettled weather conditions of early summer. To Greek observers, this signified certain emanations which caused its malignant influence. Anyone suffering its effects was said to be astroboletos or “star-struck.”

The Old Farmer’s Almanac lists the traditional period of the Dog Days as the 40 days beginning July 3rd and ending August 11th, coinciding with the ancient heliacal (at sunrise) rising of Sirius.