Ep. 295: The Observable Universe
We understand our place in the Universe because of our direct observations. We can see the light that travelled billions of light years across space to reach us. This sphere of space is the observable universe; everything we can detect. But it’s really just a fraction of the larger, unobservable universe. Today, we’ll talk about both.
Ep. 294: The Arecibo Observatory
The mighty Arecibo Radio Observatory is one of the most powerful radio telescopes ever built – it’s certainly the larger single aperture radio telescope on Earth, nestled into a natural sinkhole in Puerto Rico. We’re celebrating the 50th anniversary of the construction of the observatory with a special episode of Astronomy Cast.
Ep. 293: Earthquakes
We always say that the Universe is trying to kill you, but actually, the Earth isn’t so fond of you either. Certain parts of planet Earth are prone to earthquakes, where the planet’s shifting plates can cause the ground to shake violently. We’ve had a few devastating earthquakes in recent years, but do they also happen on other worlds?
Ep. 292: The Oort Cloud
The very outer reaches of the Solar System is a region of space known as the Oort Cloud, which may extend as far as a light-year from the Sun. We only know about the Oort Cloud because that’s where long-period comets come from, randomly falling into the inner Solar System from time to time.
Ep. 291: Shockwaves
As a meteor crashed into the atmosphere above Russia, the world discovered the importance of shock waves; how they’re caused and how they propagate through the atmosphere. Today we’ll discuss the topic in general and find many examples where shock waves can be created, here on Earth, and out in space.
Ep: 290 Failed Stars
If you get enough hydrogen together in one place, gravity pulls it together to the point that the temperature and pressures are enough for fusion to occur. This is a star. But what happens when you don’t have quite enough hydrogen? Then you get a failed star, like a gas giant planet or a brown dwarf.
Ep. 289 Cherenkov Radiation
Sure, our atmosphere protects us from a horrible Universe that’s trying to kill us, but sometimes it prevents us from learning stuff too. Case in point, the atmosphere blocks highly energetic particles from reaching our detectors. But there’s a way astronomers can still detect their influence: Cherenkov Radiation; the cascade of radiation that blasts out as a high-energy particle makes its way through the atmosphere, like a radioactive rainshower.
Ep. 288 Phases of Matter
As we quickly learn with water, matter can be in distinct phases: solid, liquid, gas and plasma; it all depends on temperature. But why do different materials require different temperatures? And what’s actually happening to the atoms themselves as the material switches phases?
Ep. 287 E=mc^2
It’s mind bending to think about this, but the light in your house, and the house itself are really the same thing. Matter and energy are interchangeable. This was the amazing revelation made by Albert Einstein, with his famous formula: E=mc^2. This is the process that the Sun uses to turn hydrogen into radiation through fusion, and the terrible damage from a nuclear weapon.
Ep. 286 How to Debunk an End-of-the-World Myth
Everyone is always predicting the end of the world. Someone’s going to tell you that this the year that it’s all going to end… the end of planet Earth… and they’re always wrong. But, someone will eventually be right. Planet Earth is doomed, lets figure out how.