Star Luminosity Classes


What do you think it would mean for a star to be in a specific luminosity class? I mean…does that mean they go to school to learn how to be bright?

(Ha, ha…yeah, I know, bad astronomy pun.)

Well…not quite.

Stars can be sorted in a lot of ways—and a good thing, too, because there are literally trillions upon trillions of them. Astronomers would be lost if we couldn’t sort them into groups to study.

They can be sorted according to spectral type (composition and temperature), apparent visual magnitude (how bright they look to the naked eye from Earth), and absolute visual magnitude (how bright they would look to the naked eye from ten parsecs away).

They can also be sorted according to their absolute bolometric magnitude (how bright they would look from ten parsecs away if the human eye could see all types of radiation).

And…they can even be sorted according to their luminosity. Continue reading

Star Stuff & Cecilia Payne


If this quote really is from Cecilia Payne, then she had the right idea—at least for a female astronomer in the 1920s. Women in science back then faced an uphill battle to get recognized for any discoveries they made, and Payne was no different.

What’s so special about Payne, you might ask? Well, she wasn’t just one of the many “unsung heroes” of modern science. She was the one who figured out what stars are made of.

Yeah, that’s right. She sent a probe to the sun, collected a jar of star stuff, and brought it back to her laboratory…

Um, no, not really. It wasn’t that easy.

In fact, it was very difficult. She had far too many roadblocks than were fair. But she wasn’t out for money or recognition. She was just in it for the science. And science was what she got…

Continue reading

The Balmer Thermometer

hot star.jpg

How hot would you say this star is? Take a wild guess.

Well…sorry, but I’m going to stop you for a moment just to make sure we’re all using Kelvins. The Kelvin scale is like the Celsius scale, except water freezes at 273 K instead of 0℃. 0 K is absolute zero, which is purely theoretical and doesn’t exist.

Now can you guess this star’s temperature?

I’ll give you another hint. This is a real photograph, so it’s impossible for this star to be any star other than our sun. How hot do you think our sun is?

Okay…I’ll tell you. It’s about 5800 K, which—for those of you unfamiliar with Kelvins—is about 5527℃. Kinda crazy, huh?

Next question. How do we know this? I mean, it’s not like we stuck a thermometer in the sun’s surface and actually measured it, right? Continue reading

Types of Atoms


Does this look familiar?

It might, or it might not. If it does, you might recognize it as the periodic table of the elements—more often known as simply the “periodic table.” It’s an ingenious way to organize elements that has worked for scientists for quite some time.

To fully appreciate the ingenuity of the periodic table, I’d have to take you through a few chemistry lessons. Never fear, I have every intention of doing so—later. For now, though, I just want to address enough of the world of atoms to talk about stellar spectra.

That just means the spectrums we get from stars, by the way. (Spectra is plural for spectrum.) And that means…well…we’ll talk about it later. Let’s talk about the different types of atoms first.

Atoms are the building blocks of the universe. Which means there must be different types. But what are they? Continue reading

Info in a Rainbow

milky way.jpg

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

Elements and Compounds



Recognize this?

This is the periodic table, and it’s pretty much the most important table in all of chemistry.

All the little boxes on this “table” are elements, the simplest form of matter. You literally can’t break these down further. What’s the difference between an element and a substance, you ask?

Okay, well, think of it this way. In my post on matter and its forms, I used water as an example of a substance. Water has its own physical and chemical properties, it’s not a mixture of anything, and no matter how many times you divide it up, you’ll still have the same thing.

But water can be divided up into different things chemically. Continue reading