Astronomy Cast - Ep. 72: Cosmic Rays

Ep. 72: Cosmic Rays

This active galaxy (3C442A) is emitting high-energy particles through its poles, as you can see with the xray/radio composite. credit: X-ray: NASA/CXC/Univ. of Bristol/Worrall et al.; Radio: NRAO/AUI/NSF

We’re going to return back to a long series of episodes we like to call: Radiation that Will Turn You Into a Superhero. This time we’re going to look at cosmic rays, which everyone knows made the Fantastic Four. These high-energy particles are streaming from the Sun and even intergalactic space, and do a wonderful job of destroying our DNA, giving us radiation sickness, and maybe (hopefully!) turning us into superheroes.

Episode 72: Cosmic Rays (13.3MB)

Ep. 68: Globular Clusters

M80 is a globular cluster 28,000 light years away containing thousands of stars. credit: The Hubble Heritage Team (AURA/ STScI/ NASA)

This week we're going to study some of the most ancient objects in the entire Universe; globular clusters. These relics of the early Universe contain hundreds of thousands of stars, held together by their mutual gravity. Since they formed together, they give astronomers a unique way to test various theories of stellar evolution.
Episode 68: Globular Clusters (14.3MB)

Ep. 37: Gravitational Lensing

Galaxy cluster Abell 2218 is acting as a powerful lens, magnifying all galaxies lying behind the cluster core. credit: ESA, NASA, J.-P. Kneib (Caltech/Observatoire Midi-Pyrénées) and R. Ellis (Caltech)

Astronomers are always trying to get their hands on bigger and more powerful telescopes. But the most powerful telescopes in the Universe are completely natural, and the size of a galaxy cluster. When you use the gravity of a galaxy as a lens, you can peer right back to the edges of the observable Universe.

Episode 37: Gravitational Lensing (12.7MB)

Ep. 26: The Largest Structures in the Universe

The Silver Dollar Galaxy, NGC 253 credit: R. Jay GaBany, cosmotography.com

This week we continue the story of galaxy formation, learning how groups of galaxies come together to form the biggest structures around - galaxy superclusters. And when you look at the Universe at this scale, environment is everything.

Episode 26: The Largest Structures in the Universe (15 MB)

Ep. 25: The Story of Galaxy Evolution

Sombrero Galaxy in Infrared credit: R. Kennicutt (Steward Obs.) et al., SSC, JPL, Caltech, NASA

Our Milky Way is a complex and majestic barred spiral galaxy. But 13.7 billion years ago it began, like all galaxies, from the elementary particles formed in the Big Bang. How did our galaxy grow from nothing to the hundreds of billions of stars we see today?

Episode 25: The Story of Galaxy Evolution (13.8 MB)

Ep. 18: Black Holes Big and Small

Black Hole (Artist Illustration) credit: NASA/CXC/M.Weiss

We're finally ready to deal with the topic you've all been waiting for: Schwarzschild swirlers, Chandrasekhar crushers, ol' matter manglers, sucking singularities… you might know them as black holes. Join as as we examine how black holes form, what they consume, and just how massive they can get.

Download Episode 18: Black Holes Big and Small (13 MB)