Sirius

The brightest star in our whole night sky.

Also called: the Dog Star, the brightest star.

🕒 When can I see it?🚀 Travel there

What it is

Brightest star in the night sky, a hot blue-white star about twice the Sun's mass.

Star: A ball of gas heavy enough to fuse hydrogen in its core. Every kind of thing there is →

How to find Sirius

Look in the constellation Canis Major.

Stays low and can be hard to spot from far northern latitudes.

Finding it: Found by following Orion's Belt downward.

The Planetarium works out where it actually is from your own place and the date — including whether it is above the horizon at all tonight.

Show me Sirius in tonight's sky

What you will really see

With your own eyes

A bright point of light — even big telescopes can't show a star as a disc.

Honest, not glamorous — why the pictures here are drawn.

🔭 See it drawn as it looks through a telescope

Worth knowing about Sirius

In weight, about twice as massive as the Sun. On the 100-meter-track scale model of the Milky Way, Sirius would be less than a centimeter from the Sun -- about the size of a pea. Light takes 8.6 Earth years to get here from Sirius, so what you are looking at is Sirius as it was 8.6 Earth years ago.

How bright it is: Shines about 25 times brighter than the Sun.
What it is made of: A hot, blue-white star about twice the Sun's mass.
What makes it worth knowing: Looks brightest not because it's the closest star, but because it's both close and genuinely luminous.
Its name and its story: Ancient Egyptians tracked its heliacal rising to predict the Nile's flood. Greeks/Romans blamed its glare for the 'dog days' of summer. Center of the disputed 20th-century 'Dogon mystery' claim.

The numbers