The HR diagram

First, let’s look at temperature on the bottom of the diagram.

Temp increases from right to left The HR Diagram hot (blue) cool (red) Temp increases from right to left

Next, let’s look at luminosity on the left of the diagram. Remember…luminosity compares the brightness of stars to the brightness of our sun.

Luminosity increases from bottom to top The HR Diagram bright Luminosity increases from bottom to top dim

Now, let’s find our sun on the HR Diagram.

The HR Diagram Our Sun

Our sun is an average star in the main sequence stage of its life cycle.

The HR Diagram Hottest and brightest Main Sequence Stars Our Sun Coolest and dimmest

As stars move through their life cycle, their temperature changes causing them to move around the HR Diagram.

Very bright; not that hot; large in size The HR Diagram Supergiants Very bright; not that hot; large in size Our Sun

Less bright; similar temp to supergiants; smaller in size The HR Diagram Red Giants Less bright; similar temp to supergiants; smaller in size Our Sun

The HR Diagram Our Sun White Dwarfs Very hot; dim; small

Last, but not least, let’s color our HR Diagram to match the temperature.

The HR Diagram