THESE clear, frosty nights are absolutely perfect for stargazing, writes STUART ATKINSON. With no mist or cloud in the sky during the day, when darkness falls the sky is a spectacular sight, strewn with jewel-like stars, all twinkling and flashing through the night. And none of them look more beautiful than Sirius, the brightest star in the whole sky.

Amateur astronomers like to explain how the best way of finding Sirius is to first find Orion's Belt and then extend it down to the left, but you don't actually need Orion's Belt as a guide. If you go out at around 10pm on the next clear night and just look east you'll see Sirius blazing just above the trees in that direction, far brighter than anything else in the sky (unless the Moon is on view).

Why is Sirius so bright? For one thing it's close to us, just under nine light years away, making it one of our nearest neighbours. It's also a lot more powerful than our own Sun. So when you're looking at Sirius - also known as the Dog Star - you're looking at a fiercely bright alien sun almost on our cosmic doorstep.

Sirius is a beautiful silvery-white colour, and looks like a finely cut diamond shining in the sky. Although it is well known for the way it sparkles, twinkles and dances in the sky, it's not actually varying in brightness; the star's low altitude as seen from the UK means we view it through more air than stars higher in the sky, and as that air moves around Sirius appears to twinkle crazily.