Stars are hot. Space is cold. We’re all familiar with that, right?
Technically, it’s more complicated than that. Space isn’t completely frigid—absolute zero, the temperature at which there is no heat whatsoever, is purely theoretical and not thought to exist in the universe. But it is pretty darn cold.
And stars aren’t always very hot—there is one newly discovered star that’s only as hot as fresh coffee. (It’s a brown dwarf, and if you go by the definition of a star as an object that’s ignited hydrogen fusion in its core, then it doesn’t actually count.)
In general, though, stars are pretty darn hot. Some special types of stars reach up to 200,000 K—that’s 359,540.33℉. Our own sun is about 5,778 K, which much cooler, but still almost ten thousand degrees Fahrenheit.
As a rule, we can think of stars as being much hotter than the space in between…except in the case of coronal gas. Continue reading
Does this sight look familiar?
If you’ve had the opportunity to observe the night sky from a dark place, far away from the light pollution of the city, on a clear night, you might have seen this before. It’s the Milky Way—our view of our galaxy from the inside.
It’s kind of like if you lived inside a frisbee. Look up toward the flat sides, and there’s not as much material to look through. But peer out at the edges of the disk, and you have to look through a lot more stars.
Most of the stars you see in the night sky are part of the Milky Way. But this is the sight we get when we stare through to the center of the frisbee.
Thing is, though, this is far from the most spectacular sight of the night sky. Continue reading
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
You probably recognize this image. You see something like it whenever you look up at the sky. Some days are clearer than others—some, you might even see a completely blue sky—but regardless, you know that this is an image of our atmosphere.
But do you know just how much your atmosphere does for you?
We’ll talk about how it protects you from space rocks later on. For now, consider the energy from our own sun. The sun doesn’t just send visible light our way—it operates in all wavelengths of the electromagnetic spectrum.
Some of those wavelengths are harmful, like gamma rays, X-rays, and ultraviolet radiation. Others, like infrared radiation, microwaves, and radio waves, are perfectly fine.
The atmosphere doesn’t really pick and choose which wavelengths get through to the surface. It blocks out some radiation it doesn’t need to. At least it protects us from the harmful wavelengths.
But that’s bad news for astronomers, because those wavelengths still contain useful information about the universe.
So how to we capture and analyze them? Continue reading
Does this look familiar?
People think of rainbows as a symbol of happiness and fortune. There are even myths that leprechauns hide gold at the end of a rainbow. That’s more of a tease than good fortune, if you ask me, because it’s impossible to reach the end of a rainbow.
That’s right. Impossible.
Some people wonder if rainbows look the same from the back. The answer’s no. They don’t. You wouldn’t see a rainbow if you were standing behind it.
Whoa…why would that be? Continue reading