Age– As a star ages it produces different chemicals which burn at different temperatures. We can use a star’s color to show its relative age Scientists can also measure the movement of a star relative to us using its spectrum. If a star is moving away from us, it’s visible light shifts toward the red end of the spectrum, which is why it’s known as a ‘redshift’. The y-axis describes luminosity compared to our sun on a logarithmic scale, so the sun measures ‘1’ on this scale. Stars with a luminosity of 10 The coolest stars in the sky glow red. As surface temperatures rise, colors change through orange and yellow. The hottest stars glow a lighter blue and the very hottest are a darker blue color. A list of the color of stars from hottest to coolest:

Thinking again about a campfire… the hottest part of the flame is blue-white while the cooler part is orange-red. Well, the same is true of stars! Stars are born in gas and dust nebulae composed of hydrogen and other elements. The Pleiades (M45) is a great example of this you can see for yourself in a telescope. There are several stellar classification systems but, to keep it simple, we’re going to focus on the Hertzsprung-Russell Diagram. Hertzsprung-Russell Diagram Temperature– cooler stars are red, warmer ones are orange through yellow and white. The hottest stars shine with blue light

The coolest stars have surface temperatures of about 3,000 degrees Celsius (5,400 degrees Fahrenheit) whilst the hottest are over 25,000°C (45,000°F).

Have you ever added salt to your campfire to change the color of the flame? Did you burn different substances in chemistry at school? If so, you’ve seen that different elements burn with different colors and intensities. The Hertzsprung-Russell Diagram relates a star’s surface temperature, luminosity, and absolute magnitude. Have you noticed that Betelgeuse is the only reddish star in Orion constellation? Maybe you’ve noticed other stars that shine with colors other than white? Have you ever wondered why stars are different colors? Stars in the Pleiades are predominantly bright and blue and are believed to have formed in the last 100 million years, making them only 2% of the age of our sun. Pleiades (M45) ( source)Absolute magnitude measures a star’s brightness from a set distance away. Normally, as astronomers, we use relative magnitude to say how bright a star is, but that’s measured from our view on Earth. The x-axis shows temperature in degrees Kelvin (nothing is colder than 0°Kelvin, which equals -273.15°C or -459.67°F). In the H-R Diagram, the hottest temperatures are on the left, coolest on the right. Hertzsprung-Russell Diagram, shows relationship of star color and temperature ( source). It also shows us which are the biggest stars, and which are smaller, as well as where we can find the dimmest stars. Stellar classification is a great way of using a star’s color to work out its age. More accurately, we use them to see how far along its lifespan a star is, i.e. is it new, middle-aged or near death?