We’re so familiar with the current configuration of the planets in the Solar System, but did the planets always orbit in this way? Did they form further out and then migrate inward to their current positions? And what about other star systems out there?
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.
Ep. 285 How the World Will Really End
Have you checked out the internet lately? Apparently there is some kind of rogue planet causing pole alignment and a killer solar flare that will set off a chain reaction turning the whole universe into strange-matter…. after an alien invasion.
Ep. 284 Optics
Astronomy depends on bullying light. We reflect it, refract it, bend it, and near it through complex manipulations of light. Though optics we bring we bring the distant universe to our eyepiece.
Ep. 283 Stellar Motions
Our Universe appears timeless and unchanging, the stars taking their nightly flight across the sky. But over long periods of time, you realize that our local region, and even the entire Milky Way is in constant motion. The constellations we see today would be very different millions or even thousands of years ago. Today we’ll discuss stellar motion, how astronomers detect it and how it’s useful.
Ep. 282 Seasons
Spring, Summer, Autumn and Winter. These are the seasons we experience here on Earth as our planet completes an orbit around the Sun. But what’s going on? Why do we experience such different temperatures and weather over the course of 365 days? Do other planets experience the seasons like we do?
Ep. 281 Explosions in Space
We’ve all seen the classic science fiction space explosions, full of flames and loud sounds. Beautiful on the screen but, totally lacking in any kind of… science. What’s wrong with science fiction? What would chemical and nuclear explosions really look like? What would we hear? And what are some natural explosions that nature detonates in space?
Ep. 280 Cosmological Constant
In order to allow for a static Universe, Albert Einstein introduced the concept of the Cosmological Constant Lambda to make the math work out. Once it was discovered that the Universe was actually expanding, he threw the number out calling it his “biggest blunder”. But thanks to dark energy, the Cosmological Constant is back.
Ep. 279 Hubble Constant
When Edwin Hubble observed that distant galaxies are speeding away from us in all directions, he discovered the reality that we live in an expanding Universe. Hubble worked to calculate exactly how fast this expansion is happening, creating the Hubble constant – which astronomers continue to refine and reference in their research.
Ep. 278: Animals in Space
We always think about humans in space, but the cold hard reality is that animals have always been first in space. First to fly, first to orbit, and sadly, first to die. Let’s learn about how our animal companions have been our trusty partners in space exploration, and let’s recognize their noble sacrifices over decades of experiments.
Ep. 277: Orbit
When an object is orbiting the Earth, it’s really falling. The trick, described in the Hitchhiker’s Guide to the Galaxy, is how to throw yourself at the ground and miss. There are several different kinds of orbits, and they are good for different reasons. From suborbital jumps to geostationary orbit, time to learn everything there is to know about going around and around and around.
Ep. 276: XMM-Newton
The Earth’s atmosphere keeps us alive and blocks x-ray radiation from reaching the surface. In order to understand the universe at the higher energy levels you need to launch a space telescope like the European Space Agency’s XMM-Newton Telescope. Let’s learn about the telescope named for the famous scientist.
Ep. 275: Isaac Newton
Isaac Newton has been called “the greatest and most influential scientist who ever lived.” That sounds about right. He unlocked our modern understanding of gravity and laws of motion, dabbled in optics, philosophy… even alchemy. He was also known to have a bit of a difficult personality. Let’s find out everything we can about Isaac Newton.
Ep. 274: Vesta
There’s some topics on Astronomy Cast that we wait until we are good and ready, until the science is all in. The Dawn mission has completed it’s mapping operations at asteroid Vesta and it’s now moving on to Ceres. This gives us a great opportunity to take a detailed look at this amazing asteroid, report on the science findings, and give you a preview of what’s coming next.
Ep. 273: Solutions to the Fermi Paradox
In Episode 24 we presented the concept of the Fermi Paradox. In short: Where are all the aliens? Today we’re going to examine the theoretical solutions to this problem. Maybe they’re out there, but just don’t want to talk to us. Maybe it’s too hard to communicate? Maybe there are no other civilizations. Maybe civilizations wipe themselves out when they reach a certain point. So many solutions, none of them satisfactory.
Ep. 272: Abiogenesis
The Theory of Evolution provides a rich explanation for why we see the diversity of life here on Earth. There are so many lines of evidence, from genetic drift to the fossil record. But how did life start? How did things go from a collection of raw materials to the building blocks of life, giving evolution and natural selection a way to take over? That first step, from non-life to life is called “abiogenesis”, and it’s one of the most important questions science can answer.