Star · White · Canis Major

Sirius

9 CMa · HIP 32349

Above the horizon after darkHighest after dark 05:17 · southeast · 19°

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Where is Sirius?

Times for LondonChange city

Look southeast, about 19° up at 05:17 in Canis Major. It rises at 02:12 and climbs through the night.

Rises: 02:12
Highest: 06:47
Sets: 11:21
Best after dark: 05:17 · 19°

Can I see Sirius tonight?

From London tonight, Sirius is above the horizon after dark. It’s highest just before dawn, around 05:17, in the southeast at 19°.

At magnitude −1.5 it is one of the brighter points in the sky, easy to see by eye when it’s clear.

This is position and timing only: clouds, haze and light pollution aren’t included.

What does Sirius look like?

Sirius looks white to the eye. Its spectral type is A0mA1 Va: white main-sequence star (hotter than the Sun).

Eyes

A brilliant white star. Low in the sky it twinkles strongly and can flash red, green and blue.

Binoculars

An intense white point. The colorful twinkling is even more obvious when Sirius is low.

Telescope

Still a point of light. Its faint white-dwarf companion is very close and drowned in glare; seeing it takes a good telescope, steady air and the right years of its 50-year orbit.

What you’re likely to see, not what a space telescope photographs.

About Sirius

Sirius is the brightest star in the night sky, nearly twice as bright as the runner-up, Canopus. Its name comes from the Greek for “glowing” or “scorching”, and it is often called the Dog Star because it leads the constellation Canis Major, the Great Dog.

It looks so bright because it is both luminous and close: about 25 times more luminous than the Sun and only 8.6 light-years away, one of our nearest neighbors.

Sirius has a faint companion, Sirius B, a white dwarf about the size of Earth but with roughly the mass of the Sun. It is the leftover core of a star that burned out long ago.

When Sirius is low, the turbulent air near the horizon makes it twinkle wildly and flash different colors. That is the atmosphere at work, not the star.

In ancient Egypt, the first sighting of Sirius in the dawn sky after weeks hidden in the Sun’s glare marked the season of the Nile’s yearly flood.

Sirius in Canis Major

Questions

Why does Sirius flash colors?

Its light passes through a lot of turbulent air when it is low. The atmosphere bends different colors by slightly different amounts, so the star seems to flicker through a rainbow.

Is Sirius the closest star?

No, but it is among the closest. Only a handful of star systems, including Alpha Centauri, are nearer.

Why is it called the Dog Star?

It is the brightest star in Canis Major, the Great Dog, one of Orion’s hunting dogs.

Its constellationCanis Major Another starCanopus Another starRigil Kentaurus 4° awayMessier 41 5° awayMirzam GuideStargazing for beginners

Sources: SkyMate; Wikidata (CC0). Positions computed for your place and time with astronomy-engine. Data & Licences