All of you have read phrases like “the brightness of a star is equal to…” or “the star is brighter than the planet Saturn”. Sounds a little strange, doesn't it? A polished penny, a copper basin in the sun, buttons on a tunic can shine. After all, eyes may shine. But can a star do this? It seems that there is something ridiculous and slightly archaic in the phrase star glitter. The term star shine is not an outdated expression, but the most relevant, modern term. Astronomers mean the brightness created by a celestial object (for example, a star) on a plane perpendicular to the line of sight.
The higher the brightness of the star, the more it illuminates our eyes, the better we see it! The brightest stars in the sky are visible at night well. Stars with low brightness are poorly visible, or not at all visible without a telescope. We say these stars are dim.
Since the concept of brightness in astronomy has a strictly scientific definition, then brilliance can be measured. Indeed, the brightness of stars (and indeed any celestial bodies) is measured in stellar magnitudes. A magnitude is a special dimensionless physical quantity that is used only in astronomy and astrophysics. It is denoted as a Latin letter m above its numerical value. For example, the brilliance of Sirius is -1.44m. Stellar magnitudes are measured paradoxically: the smaller the value of m, the higher the brightness of a celestial object. Read more in the article "What is magnitude?"
In addition to stellar magnitudes, the brightness of celestial objects can be measured in traditional physical quantities, for example, in lux. The relationship between magnitude and lux is as follows: m = -14 - 2.5lgJ, where J is the value in lux. Thus, the star Vega, which has an apparent brightness of about 0m, creates an illumination of 0.00000254 lux. The full moon creates an illumination of 0.25 lux.
Star brightness is the amount of light coming from a unit area of an object. Therefore, the term brightness applies only to extended objects - the Sun, the Moon, planets (already in a small telescope they can see disks!), Comets, nebulae. And the term brightness is no longer applicable to point stars or meteors without width because they have no area! But the term shine is applicable because it characterizes the illumination created by any celestial body, even nebulae, even stars.
Would you like to know that there is a star with your name? Now, you can choose the lucky star that will shine brightly for you. Cosmonova is the place where you can name the star and leave your name in eternity.