Star Colors!
Our closest star, the sun, is a miasma of incandescent plasma -- superheated gas shining
out into our solar system and beyond.
If an extraterrestrial being looked up at their night sky and spotted our star, they’d
see a white speck.
“But Trace,” you might be thinking.
“The sun is sometimes yellow, or orange or red!”
And this is true, lovely viewer!
The sun can APPEAR to be those colors, but that’s mainly an illusion due to our atmosphere.
Astronauts see the sun as a bright white source of our heat and light.
When you look up at the night sky, it’s hard to miss all those white specks of starlight,
but if you look closer, you’ll notice that not all the stars ARE white -- some are red,
orange, yellow, and even blue!
Because of Orion’s position in the sky it is one of the most loved winter constellations,
but it can be visible very early in the morning at other times of year.
Regardless, next time you see The Hunter, look closely at the two brightest stars, and
you’ll notice the top left star, his right shoulder, is RED.
That’s Betelgeuse, a dying red giant star.
It’s cooler than our sun, which means it burns redder.
Red Giants are stars that are nearing the end of their lives.
At that point they start to expand and cool off…
Betelgeuse varies between 500 and 900 times larger than our star!
If it were sitting where our sun is now, we’d be inside B’s surface.
But, tucking back out to all of Orion -- shift to the bottom right side of the constellation,
Orion’s left foot -- that’s Rigel, and if you really look, you might notice that
it’s BLUE.
Rigel is a blue supergiant star and one of the brightest in the night sky.
Rigel is 70 times larger in diameter, 40,000 times brighter, and twice as hot as our own
sun.
If we were orbiting Rigel at the same distance as we do our sun, we’d burn up!
To have comfortable temperatures like we do now, we’d have to be five times further
away from Rigel than Pluto is from the sun.
That’s so far!
Star colors aren’t arbitrary.
The color of a star has to do with what it’s burning and its surface temperature.
Cooler stars are redder, hotter stars are bluer -- this is the opposite of how your
faucets work at home... because fire.
Instead, think about the flame of a Bunsen burner in science class!
Blue flames are hottest, red flames are cooler.
Our sun shines at about 6,000 Kelvin, but Betelgeuse is a cool 3,000 Kelvin, and Rigel
is a spicy 11,000 Kelvin.
The closer you look at the sky, the more colors you’ll see!
Look for Spica, Vega, Alpheratz, and Bellatrix for more blue stars and remember that means
they are hotter.
Then look for Mirach, Antares, Aldebaran, and Arcturus for spectacular red stars -- and
remember, those are cooler.
Stars are incredible things, and there are many reasons to be captivated by them, other
than their shine.
Just like living things stars are born, they age, have complex lives, and eventually they
die -- but throughout their lives they are all varied and unique.
Colors are one of many characteristics astronomers can use to learn more about these incredible,
massive balls of fusion, and now you’ve got one more tool in you astronomical tool
belt.
Keep looking up.