LOOK to the south straight after dark and you'll see the (hopefully!) now-familiar hourglass shape of Orion, The Hunter standing there. If you look down to the lower left of Orion, following the three blue stars of its famous 'belt' down towards the horizon, you'll see a very bright star shining there, above the trees or hills. This is Sirius, aka the Dog Star and it is the brightest star in the whole sky.

Sirius is one of the closest stars to us, only 8.6 light years away, so when you look at it the light entering your eyes set off almost 9 years ago, when Take That were singing first Shine on TV. This makes it one of the nearest stars visible to the unaided eye from our part of the world. It's almost twice as large as our Sun, and much hotter too, with a surface temperature of more than 9,000 degrees Celsius.

When you look at Sirius you'll see it appears to be twinkling and flickering away like crazy. That's just the light from the star breaking up as it passes through the atmosphere; in reality the star shines with a steady, blue-white light. If you have a basic pair of binoculars, aim them at Sirius and you'll see it flashing like a jewel, glittering with beautiful blues, reds, greens and whites as its light is scattered by the air. This is why it is sometimes called the Rainbow Star by sky watchers.