How much do you know about the brightest star of the night sky, Sirius, and its constellation, Canis Major? For example, did you know that the Canis Major contains a star that is actually way brighter than Sirius in terms of absolute magnitude? Or that it has a star cluster called Pirate’s Jewels? Keep reading to learn more surprising facts!
How to find the Sirius star?
The night sky’s brightest star, Sirius, is sure to catch your eye in the evening sky this time of the year. Once the sky darkens after 7:30 p.m. local time, Sirius will be sitting in the southeastern sky, to the lower left of Orion. Sirius will reach its highest position over the southern horizon at 9 p.m. and then descend into the southwestern sky and set by 2 a.m. local time.
Despite that Sirius lies in the Southern Hemisphere, it is visible from almost everywhere, except latitudes north of 73° N. It also doesn’t rise high for some northern cities; for example, it reaches only 13° above the horizon from Quebec, Canada.
You can easily locate the star in the sky via the Sky Tonight app. Just open the app, tap the magnifier icon in the lower-left corner, and type “Sirius” in the search bar. Then tap on the target icon, and Sky Tonight will show you the star’s location in the sky.
Why is Sirius so bright?
Sirius is so bright because it is about 25 times more luminous than our Sun and is only a mere 8.6 light-years away from Earth. Furthermore, it is heading towards us and will brighten over the next millennia! Sirius has a tiny companion — a white dwarf star designated Sirius B, that some astronomers call the Pup.
Why does Sirius twinkle so much?
Sirius is famous for exhibiting flashes of intense color as it twinkles. This is because the Northern Hemisphere observers usually see the star positioned low in the sky so that its very bright light is passing through a thicker blanket of air. The pockets of turbulence in our atmosphere that makes stars twinkle also work like tiny refracting prisms — splitting apart Sirius’ white light and randomly sending different colors (wavelengths) to our eyes.
What is the common name for the star Sirius?
Sirius’ name means “searing” or “scorching” in Greek. It’s also commonly known as the Dog Star because it is the brightest star in the constellation Canis Major, which means the Big Dog in Latin.
Another Sirius name (that you probably hear less often) is Alpha Canis Majoris. Usually, the brightest star of any constellation is designated so.
Canis Major, the Big Dog
The dog’s head is formed by a triangle of medium-bright stars to Sirius’ upper left, but those are near the limit of visibility in urban skies. Nose to tail, the constellation covers about 19° or two fist diameters. From ears to paws, he spans about one fist diameter. The rest of the dog’s body, composed of more easily visible stars, extends to the lower left of Sirius.
What are the major stars in Canis Minor?
Below Sirius shines the bright star Wezen, which marks the dog’s “bottom.” The tip of the dog’s tail, marked by a modest star named Aludra, is in the lower left of Wezen. Above Wezen, you’ll find two less conspicuous stars positioned side-by-side and separated by two finger widths. They nicely denote the dog’s slim torso. The left-hand star is whitish Al Zara (HR 2580). To the right is fainter and orange-tinted star Udra (HR 2653). Both stars are designated Omicron Canis Majoris.
To the lower right of Wezen, a bright star named Adhara represents the dog’s rear legs. Some representations include two dimmer stars for the rear paws.
The dog’s front legs are formed by the bright star Beta Canis Majoris (Mirzam) located to the lower right of Sirius. Beta Canis Majoris is 60 times more luminous than Sirius. If that star were located where Sirius is, instead of 500 light-years away from us, it would appear 15 times brighter than Venus!
Deep-sky Objects in Canis Major
In the heart of Canis Major, below Sirius, is a bright little cluster of stars designated Messier 41, sometimes called the Little Beehive Cluster. Binoculars should show it easily. The cluster, which is about 2300 light-years away from us, consists of several brighter golden stars and numerous fainter ones.
Another nice cluster named NGC 2354 sits on the upper left of Wezen. An even nicer cluster sits to the left of Wezen. It’s formally known as the Tau Canis Majoris Cluster (NGC 2362), and also the Mexican Jumping Star and Pirate’s Jewels Cluster.
A bright little nebula with an unusual shape is located on the upper left of Sirius. NGC 2359 is aglow with a mixture of reddish light from ionized hydrogen and some blue light scattered by interstellar dust. “Wings” of gas flanking the main zone have given it the nick-names Thor’s Helmet, the Duck Nebula, and the Flying eye Nebula.
Now you know how to spot Sirius and what else to view in the constellation Canis Major. On the next clear evening, have a look at our bright neighbor.
We wish you clear skies and happy stargazing!
Text Credit: Chris Vaughan