A Star's Brightness
Below is a Hertzsprung–Russell diagram (HR diagram). The diagram originated in 1912 when two astronomers, Ejnar Hertzsprung and Henry Norris Russell, both discovered that the brightness and colour of a star depends on its surface temperature. Despite them coming to this realisation at the same time, they made this discovery separately. Together, they came up with this diagram that explains the brightness, temperature and classes of stars.
The letters across the bottom represent the colour of stars.
O – Blue
B – Blue/White
A – White
F - White/Yellow
G – Yellow
K – Orange
M - Red
The temperature of the stars, measured across the bottom of the scale are measured in Kelvins. Zero Kelvins is equal to -273 degrees Celsius. On this diagram there are only a few categories of stars. Most stars in our universe are main sequence stars, this happens to include our Sun.
The letters across the bottom represent the colour of stars.
O – Blue
B – Blue/White
A – White
F - White/Yellow
G – Yellow
K – Orange
M - Red
The temperature of the stars, measured across the bottom of the scale are measured in Kelvins. Zero Kelvins is equal to -273 degrees Celsius. On this diagram there are only a few categories of stars. Most stars in our universe are main sequence stars, this happens to include our Sun.