Star Luminosity Classes

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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

Life vs. Rocks: What Makes Them Different?

Welcome to my third “Science Answers” post! About a month ago, I sent out a post requesting science questions from all of you; you can find it here. This post addresses the third of the questions I was asked. If you have a question, you can ask it in the comments here or on that post, or ask it in an email. Or find me on Facebook!

Q: What is the division between the physical and life sciences? For example, why do we think of rocks in a different category than we do plants and animals? (asked by Katherine)

Okay, wow. Another great question! This one is almost as fundamental as gravity, which I answered earlier.

Gravity may be pretty much the singular reason why the universe works the way it does, but the difference between the physical and life sciences is an important distinction when trying to understand the world around us.

So let’s start with what we know. When you hear “physical science,” what do you think of?

 

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You might think of any number of things—but I’ll bet you that none of those things are alive in the traditional sense.

So, how about the biological sciences? What does that make you think of?

 

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Maybe plants…or cute animals?

Whatever you think of, I’m going to guess they’re all alive.

But what makes something alive or not alive? What makes zebras leap and run, whereas rocks are forever immobile? What makes these living beings different from a vast galaxy or the Pillars of Creation? Continue reading

The Proton-Proton Chain

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Take a wild guess: how much energy do you think the sun generates?

Think about it. It definitely generates enough energy to power a world.

Humans depend on the photosynthesis of plants, which converts sunlight into energy. And that’s not all. Without energy from the sun, our atmosphere would behave very differently, and so would our oceans.

Everything that moves on Planet Earth does so because it has energy. And a lot of that energy comes from the sun. It doesn’t even stop there—obviously, the sun has plenty of energy to spare, if the recent influx of solar power means anything.

The sun is incredibly powerful. And it’s powerful enough to keep generating that kind of massive energy supply for billions of years.

So where does it get all its energy? Continue reading

Our Sun: The Chromosphere

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This diagram is a tiny bit misleading.

Here, it looks like the chromosphere is the visible surface of the sun, with the photosphere just below. Really, we never see the chromosphere. If you ever look through a solar telescope at the sun, the photosphere is the surface that you see.

The sun is structured a lot like the Earth, just in that it has a core, a dense region between the core and the surface, a “surface” layer, and a few atmospheric layers. The chromosphere is part of that solar atmosphere. And you never see it.

Well…almost never. Continue reading

Star Stuff & Cecilia Payne

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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 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

Stars and Radiation

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Stars are hot.

Really hot. Hot enough to have energy to spare for their planets. If our star wasn’t hot, we couldn’t live on Earth. And our star isn’t even particularly hot for a star. It’s a middle-aged star of low mass, so it’s relatively cool compared to other stars.

You might also notice that stars aren’t all the same color. There are redder stars and bluer stars and more whitish stars.

We know stars are hot. They’re also bright. And they’re different colors. But how does that all translate to radiation—and how can we see it? Continue reading

Atoms and Radiation

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Everything we know about space comes from radiation.

Now wait just a moment here. That statement explains how astronomy is such a successful field of science—it’s based entirely on the information we can glean from radiation, after all. But how does that make sense?

I mean, it’s one thing to study radiation. It’s quite another thing to study matter, the “stuff” in the universe. How does one have anything to do with the other?

Well…that’s where atoms come in. Radiation does, in fact, have a lot to do with the “stuff” it comes from. And if it weren’t for that basic principle, astronomy as a science wouldn’t work.

Thankfully for astronomers, it does. So what’s the secret, then? What does radiation have to do with matter? Continue reading

How Atoms Work

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Have you ever seen something like this?

I’m going to venture a wild guess and say you haven’t, since scientists have only recently been able to take this kind of image. I learned about it in my biology class this semester, and the professor said that it was a landmark achievement.

You’re looking at an atom.

Yes, that’s right. You’re looking at a single, microscopic building block of matter.

Let me give you an idea of just how small this is. Millions of the smallest atom in the universe can fit lined across the diameter of a single pinhead.

But I’ll ask you another question. If I showed you an image like the one below, would you immediately think, “atom”? Continue reading