Types of Stars

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Meet the sun: a G2 class star towards the middle of its lifespan.

Wait a second…G2? What does that even mean?

It’s all part of a way astronomers break down the billions of stars in the sky and organize them by temperature. They can use a star’s spectrum to figure out what it’s made of, and that helps them figure out how hot it is.

But really…being able to read stellar spectra (plural for spectrum) is only so helpful. There are billions. It helps to have an organizational system.

That way, if an astronomer sees a stellar spectrum that looks a certain way, they can know immediately that it’s a certain class of star.

So…how exactly are stars classified? Continue reading

The Atomic Spectrum

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Astronomers know that if white light passes through a prism and is bent, it’s separated out into its component colors—the colors of the rainbow.

Astronomers also know that when light interacts with atoms, the building blocks of the universe, the atoms absorb photons of light and reemit them—but in a different direction.

Put these two bits of knowledge together, and astronomers now have everything they need to understand spectra (the plural for spectrum).

spectrum is something I’ve covered in previous posts. In astronomy, it means the wavelengths of electromagnetic radiation spread out so we can analyze them individually. And it’s an astronomer’s most valuable tool.

So, what exactly is a spectrum, and how can we use it to analyze radiation from space and learn more about the universe? Continue reading

Info in a Rainbow

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What do you see in this image?

If you’re from a larger city and haven’t had the opportunity to venture into a place like the desert, you might not know what you’re looking at. That’s the Milky Way, our name for our galaxy.

Inside this galaxy are billions of stars, including our own. Galileo Galilei was the first to discover that it was really many tiny points of light, not just a cloud-like haze across the dark night sky.

We can’t see our galaxy from outside, but we can learn a lot about it by looking out at it from within. It’s difficult. It’s like trying to learn about a building if you can never step outside one of its rooms.

But we can do it, with the help of the spectrograph. Continue reading