Hey, Phil Plait here and this is Crash Course Astronomy. In last week’s episode, I mentioned that nearly all the information we have about the Universe comes in the form of light. But how does that light get made? What can it tell us about these astronomical objects? And honestly, what is light? Here’s a… Read More »
When you look at a diagram of the solar system, you’ll see a big gap between Mars and Jupiter. A few centuries ago, that gap bugged astronomers; they really wanted there to be a planet in there. On the first day of the 19th century—January 1, 1801—they got their wish. Kinda. Italian astronomer Giuseppi Piazzi… Read More »
Stars are in a constant struggle between gravity trying to collapse them and their internal heat trying to inflate them. For most of a star’s life, these two forces are at an uneasy truce. For a star like the Sun, the balance tips in its twilight years. For a brief glorious moment it expands… but… Read More »
Hey folks, Phil Plait here. In the last episode of Crash Course Astronomy, I talked about the eventual fate of the Sun, and other low mass stars like it. After a series of expansions and contractions, they blow off their outer layers, become white dwarfs, and fade away over billions of years. The end. Except… Read More »
Stars in the sky look pretty. Flickering, intense diamonds dotting the velvety night. But make no mistake: They are churning cauldrons of violence, barely constrained thermonuclear generators, creating enough energy to vaporize the Earth a thousand times over. Their lives depend on it. Heck, our lives depend on it! But in their case, how they… Read More »
Phil Plait: That is volcanoes where water and ammonia take the place of–of–you know, lava here. (laughter) (Intro) We call ours THE Moon, with a capital ‘M’, nrhhh, with the–I was gonna do quotes and then changed my mind in the middle so now it’s–(laughter)–okay. It’s about 20-something-hundred kilometers thick–22? 2250. I’ll say 22. Alright.… Read More »
Twinkle, twinkle little star. Oh. I know who you are. At first glance, stars pretty much all look alike. Twinkly dots, scattered across the sky. But as I talked about in episode 2, when you look more closely you see differences. The most obvious is that some look bright and some faint. As I said… Read More »
The sky, we now know, is full of stars AND planets. Stars are massive enough to fuse hydrogen into helium in their cores, generating energy. The heat created by that process tries to expand them, but their gravity balances that outward force, creating an equilibrium. Planets, even gas giants like Jupiter, are far too small… Read More »
I love astronomy. You may have noticed. But there’s one really frustrating aspect of it: Everything we study is really far away. Nearly everything we understand about the Universe comes from light emitted or reflected by objects. It’d be nice if we could get actual samples from them; physical specimens we could examine in the… Read More »
When an 8 – 20 solar mass star ends its life, it does so with a bang: a supernova. And when it’s all over, there’s a couple of octillion tons of superheated plasma expanding away from the explosion site at a fraction of the speed of light, a whole mess of energy released in the… Read More »