Stars and Proper Motion

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Recognize this constellation?

Well, at the time stamp of about 2000 AD (CE), I think you will. It’s one of the most famous constellations in the night sky.

Well, technically, it’s not a constellation at all.

It’s an asterism—a commonly recognized grouping of stars that isn’t actually official as a constellation. There are tons of asterisms that you no doubt recognize…the Summer Triangle, the Great Square of Pegasus, the Big Dipper.

That’s right. That mess of stars up there that keeps changing for some reason…that’s the oft-recognized Big Dipper, part of the constellation Ursa Major.

So why the heck are the stars moving? Continue reading

Energy Flow from the Sun’s Core

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Ask any climate scientist how we should power our world without fossil fuels, and they’re bound to tell you about wind and solar power.

You might be surprised to know that both of these come from the sun. Solar panels collect the sun’s energy directly, but we wouldn’t even have wind if not for the sun.

Why? Because in order to move, you need energy. And not just you. I’m talking about every speck of material on Planet Earth that shifts an inch. It’s because it has energy.

That energy can come from a lot of places. Earth is still a dynamic world with a hot interior, but it’s not hot enough to sustain all the life and other movement on its surface. A lot of our planet’s energy comes from the sun.

But here’s the big question. How the heck does it get here? 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

The Doppler Effect

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Have you ever heard the ice cream truck?

When I was little, I remember hearing the ice cream truck all the time. Just the sound of the opening notes of “Pop Goes the Weasel” were enough to propel me to the door, where I’d beg my parents to let me go out.

Of course, I didn’t always make it out front in time. But one day, my dad found a way to solve that problem—by actually getting in the car and chasing the ice cream truck.

I remember us driving around the neighborhood, following that white truck around. A few times, it slowed and stopped, but when we stopped too, it kept going again. It took a while for the driver to realize we were following him!

Eventually, we caught it, and had a good laugh over it. But the moral of the story is…have you ever noticed that you can tell if something is moving toward you or away from you, just by if it’s getting louder or quieter?

The same trick works for stars…sort of. 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

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 Balmer Thermometer

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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

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