Sirius shines bright in the January sky

As the crisp winter nights unfold in January, one celestial beacon captures the attention of stargazers around the world — the illustrious Sirius, the Dog Star. As the brightest star in the night sky, Sirius has been a subject of fascination and cultural significance throughout human history.

Sirius’s dazzling brilliance is due to its proximity to Earth, being only 8.6 light-years away. It outshines every other star in the sky, captivating observers with its unmistakable blue-white glow. Situated in the constellation Canis Major, the Greater Dog, Sirius is a double star system, with Sirius A being the primary star and Sirius B, a white dwarf, orbiting close by.

Here’s an artist’s impression of Sirius and its white-dwarf companion Sirius B (the fainter blue star at right). The two stars revolve around each other every 50 years. White dwarfs are the leftover remnants of stars similar to our Sun. Sirius B is faint because of its tiny size. It’s about 12,100 kilometres in diameter, slightly smaller than the size of our Earth. The Sun appears in this view, as a star just to the right and below Sirius.

Sirius B is difficult to view through a telescope because although it is magnitude 8.5, which should be visible with binoculars, its closeness to brilliant Sirius dazzles the eye and saturates an imaging sensor.

Across various cultures, Sirius has held profound significance. In ancient Egypt, its heliacal rising, coinciding with the flooding of the Nile, marked the beginning of the new year and was associated with the goddess Isis. The Dogon people of Mali have an intricate cosmology centred around Sirius and many Native American tribes incorporated the star into their folklore.

The winter months offer the best time to observe Sirius, as it reaches its highest point in the sky at midnight on 1 January. Throughout the month, look towards the southeast in the early evening, and you’ll find Sirius ascending, dominating the celestial landscape.

Although essentially a white star, turbulence in our atmosphere can sometimes make it twinkle violently. It can even occasionally appear to send out coloured rays, which is a spectacular sight, although the star is in reality shining steadily.