Everyone knows what the brightest star is, right? So what are you going to suggest? The North Star? Most people seem to think that, but most people would be wrong.
In fact, the North Star—called Polaris—is actually only the 48th brightest star.
The brightest star in the night sky is Sirius, also known as the “Dog Star,” and the best time to see it is upon us!
What is Sirius?
The night sky’s brightest star—and one of the closest to us. Like so many stars in the night sky, Sirius may look like a single star, but it’s actually part of a binary star system. About 300 million years old, the Sirius star system features Sirius A—a blue-white star about 25 times the mass of our Sun— and a smaller, but hotter companion star called Sirius B.
It’s nickname is “the Pup.”
The closest known white dwarf star, Sirius B’s mass is the same as that of our Sun, and its radius is slightly less than that of the Earth’s. It’s only been known about since 1862.
How to find Sirius in the night sky
Sirius is one of the easiest stars to find in the entire night sky. From the northern hemisphere just go outside a few hours after dark and look to the southeast. You will see the famous constellation of Orion the Hunter, with the three bright “belt” stars, Alnitak, Alnilam and Mintaka. These three stars point downwards to Sirius at this time of year; follow the belt’s straight line down to the southeastern horizon and you will see Sirius winking. If you can’t see it, come back in an hour and it will likely be there, sparkling brightly.
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Put some binoculars on Sirius when it’s this low and you’ll notice the rainbow-like colors of its twinkling. That’s caused by its light being refracted through Earth’s atmosphere.
Why is Sirius so bright?
Sirius is bright enough to dominate the night sky after sunset particularly if there are no planets around. It’s very bright because:
- Sirius is a big blue-white star 25 times the mass of our Sun.
- Sirius is just 8.7 light-years from the Solar System, making it the seventh closest star to Earth.
How bright is Sirius?
Sirius is almost twice as bright as Canopus, the next brightest star, which is most easily seen from the southern hemisphere (though it can be observed from Florida and Texas from January though March).
The apparent visual magnitude of Sirius is −1.46. That’s how bright it looks to us as compared to other celestial objects. Canopus has an apparent visual magnitude of –0.74 so it’s much dimmer than Sirius. It’s also 313 light-years distant!
How is a star’s brightness measured?
The magnitude scale uses a star called Vega, in the constellation of Lyra, as the standard reference star. You can see Vega right now by looking high i. the western sky after dark; its magnitude is, by definition, zero. For comparison, the Sun’s magnitude is −27, Venus can reach −4.2—depending on its phase and distance from Earth—while a full Moon is –12.7. Polaris, the North Star, has a magnitude of +1.9. Human vision can see down to a magnitude of about +6.5.
Why is Sirius called the ‘Dog Star?’
Sirius is the brightest star in the constellation of Canis Major, the Big Dog. Hence its nick-name. For the same reasons it’s catalogued by astronomers Alpha Canis Majoris. Its name Sirius is derived from a Greek word seirios meaning “scorching.”
When is Sirius at its best?
Sirius is around all winter, so you can look at it anytime after dark. However, it culminates on New Year’s Eve when it’s highest in the southern sky in the middle of the night. So all through January and February it’s high in the southern sky after dark, so easy to find.
What are the 10 brightest stars in the night sky?
Here are the brightest stars in our night sky, starting with the brightest. Note that most of them have cultural names, which is a clue that they’ve been noticed by humans throughout history:
- Sirius in the constellation of Canis Major.
- Canopus in the constellation of Carina.
- Rigil Kentaurus (Alpha Centauri) in the constellation of Centaurus.
- Arcturus in the constellation of Boötes.
- Vega in the constellation of Lyra.
- Capella in the constellation of Auriga.
- Rigel in the constellation of Orion.
- Procyon in the constellation of Canis Minor.
- Achernar in the constellation of Eridanus.
- Betelgeuse in the constellation of Orion.
Wishing you clear skies and wide eyes.