What’s That Really Bright Star Twinkling In The Eastern Night Sky This Month?

If you’ve been outside at night recently in the northern hemisphere and the weather has been clear then you’ll have noticed a very bright star in the southeastern sky.

What is it?

Venus? No—the brightest object after the Sun and Moon has been rapidly sinking in the western sky and is now almost lost in the Sun’s glare.

The North Star? No way! Also called Polaris, the North Star may be famous by name but it’s not much to look at. Due north, of course, it’s actually merely the 48th brightest star in the sky.

That really bright star you can see in the east is, in fact, Sirius. It’s the brightest star in the night sky—and that applies whichever hemisphere you’re in.

The easiest way to check you’re looking at Sirius is to find the three stars of Orion’s Belt (Alnitak, Alnilam and Mintaka) and then head diagonally down towards the eastern horizon until you come to a very bright star.

Sirius—also called Alpha Canis Majoris—is one of the closest stars to our Solar System, and it’s gradually getting closer. It shines at a magnitude of -1.4. It’s twice as bright as the next brightest star, Canopus, which can only be seen from the southern hemisphere (and not far from Sirius).

Sirius is in the constellation of Canis Major, the big dog. That’s why it’s called the “Dog Star.” The constellation itself is tricky to see all of from mid-northern latitudes, but Sirius is a simple target. Just wait a couple of hours after sunset this month and you’ll see it rise.

Although it looks like a single point of light, Sirius is a binary star system. However, Sirius A’s faint white-dwarf companion, Sirius B (sometimes called “The Pup” ), is small, dim and difficult to see even with a large telescope. That’s despite it being the largest known white-dwarf star.

Sirius is one of the few stars that are fun to point a telescope or pair of binoculars at because it appears to twinkle more than other stars. There are two reasons for this:

• Stars appear to twinkle when they’re seen low down close to the horizon (where you’ll often find Sirius) where Earth’s turbulent atmosphere is at its densest.
• Sirius is very bright, so its apparent twinkling—though merely an optical illusion—is exaggerated compared to other stars.

So go look at the brightest star tonight and you’ll forever have a bright and colorful celestial anchor in the winter night sky.

Wishing you clear skies and wide eyes.