Tecnical information
Sirius is a double or a multiple star (Sirius B is its companion); we can have double visual stars if the distance among the component is enough do that we can look them separated, with naked eye or at the telescope. This condition rarely happens because of enormous distance that separate our Earth from the stars. The double stars are generaly reveled by some measures of bright flow or by some spectroscopic tests. The temperature of Sirius is 9400° and such as all stars of spectral class "A", whose temperature is includied between 7500° and 11000°, has a white-blue colour. Surely Sirius isn't the brightest star, but for us it's the brightest one because of its distance from the Earth, about 8,7 light years away. Sirius is 23 times brightest than the sun, it is calculated that its diameter is 8 times bigger then the sun's diameter. The best period to see Sirius in mediterranean area is from January to March, but in February it's possible to see Sirius without any scientific instruments higher above the horizont.