What are magnitude, stellar distances, parsec, AU and light years?
Magnitude is a value assigned to a stellar object based on it brightness. It is usually given as a apparent magnitude (ie how bright it appears to us on Earth), but it may also be given as a absolute magnitude which is how bright it would appear (apparent magnitude) if you were 10 parsecs away from it. Apparent magnitude Object -26.8 Our Sun -12.6 Full moon -4.4 Venus at maximum brightness -2.8 Mars at maximum brightness -1.5 Sirius, the brightest star -0.7 Canopus, the 2nd brightest star 0.0 The star Vega, the zero point 3.0 Usually the faintest star you can see in a city without a telescope 6.0 The faintest star you can see in the country with no moon and no telescope 12.5 The faintest object we have seen with the telescope at Woomera 15.5 The faintest object we have photographed with the telescope at Woomera 30.0 Faintest object seen with the Hubble Space Telescope The magnitude scale is logarithmic. A first magnitude star is 100 times brighter than a 6th magnitude star. Therefore a
