Welcome to the first episode of Crash Course Astronomy. Your host for this intergalactic adventure is the Bad Astronomer himself, Phil Plait. We begin with ...
This week we build on our naked eye observations from last week and take a look at the cyclical phenomena that we can see at work in the universe. -- Table of ...
Thanks to observations of galaxy redshifts, we can tell that the universe is EXPANDING! Knowing that the universe is expanding and how quickly its expanding ...
Here it is, folks: the end. In our final episode of Crash Course Astronomy, Phil gives the course a send off with a look at some of his favorite topics and the big ...
The Milky Way is our neighborhood in the universe. It's a galaxy and there are many others out there. Galaxies contain gas, dust, and billions of stars or more.
After 10 information-heavy episodes, it's time for a little Bad Astronomy. -- PBS Digital Studios: http://youtube.com/pbsdigitalstudios Follow Phil on Twitter: ...
The fourth planet from the sun and the outermost of the terrestrial planets, Mars has long been a popular spot for missions and imagination. Phil walks you ...
The majority of the universe is made up of a currently mysterious entity that pervades space: dark energy. We don't know exactly what it is, but we do know that ...
Phil starts the planet-by-planet tour of the solar system right here at home, Earth. -- Table of Contents Earth is a Planet 0:03 Layers of Earth 1:25 The Magnetic ...
Today Phil explains how telescopes work and offers up some astronomical shopping advice. -- How Telescopes Work 1:07 Refractors vs Reflectors 2:50 ...
Active galaxies pour out lots of energy, due to their central supermassive black holes gobbling down matter. Galaxies tend not to be loners, but instead exist in ...
How do astronomers make sense out of the vastness of space? How do they study things so far away? Today Phil talks about distances, going back to early ...
We've covered a lot of incredible stuff, but this week we're talking about the weirdest objects in space: BLACK HOLES. Stellar mass black holes form when a ...
Today Phil explores the world of tides! What is the relationship between tides and gravity? How do planets and their moons become tidally locked? What would ...
Phil takes us for a closer (eye safe!) look at the two-octillion ton star that rules our solar system. We look at the sun's core, plasma, magnetic fields, sunspots, ...
Astronomers study a lot of gorgeous things, but nebulae might be the most breathtakingly beautiful of them all. Nebulae are clouds of gas and dust in space.
In this episode of Crash Course Astronomy, Phil takes you through the cause and name of the Moon's phases. -- Why the Moon Has Phases 0:36.1 Spheres in ...
Thanks to the wonders of physics, astronomers can map a timeline of the universe's history. Today, Phil's going to give you an overview of those first few minutes ...
Today on Crash Course Astronomy, Phil explains comets. Comets are chunks of ice and rock that orbit the Sun. When they get near the Sun the ice turns into ...
Join Phil for a tour of our capital-M Moon, from surface features, inside to the core, and back in time to theories about its formation. This episode is brought to you ...
In order to understand how we study the universe, we need to talk a little bit about light. Light is a form of energy. Its wavelength tells us its energy and color.
The big question in the comments last week was, "BUT WHAT ABOUT ECLIPSES?" Today, Phil breaks 'em down for you. This episode is sponsored by ...
Jupiter is the biggest planet in our solar system. The gas giant is NOT a failed star, but a really successful planet! It has a dynamic atmosphere with belts and ...
Today Phil's explaining the stars and how they can be categorized using their spectra. Together with their distance, this provides a wealth of information about ...
Today we are talking about the life -- and death -- of stars. Low mass stars live a long time, fusing all their hydrogen into helium over a trillion years.
Saturn is the crown jewel of the solar system, beautiful and fascinating. It is a gas giant, and has a broad set of rings made of ice particles. Moons create gaps in ...
In which John Green, Hank Green, and Emily Graslie teach you about, well, everything. Big History is the history of everything. We're going to start with the Big ...
Massive stars fuse heavier elements in their cores than lower mass stars. This leads to the creation of heavier elements up to iron. Iron robs critical energy from ...
Now that we've finished our tour of the planets, we're headed back to the asteroid belt. Asteroids are chunks of rock, metal, or both that were once part of ...
Now that we're done with the planets, asteroid belt, and comets, we're heading to the outskirts of the solar system. Out past Neptune are vast reservoirs of icy ...
Today we're rounding out our planetary tour with ice giants Uranus and Neptune. Both have small rocky cores, thick mantles of ammonia, water, and methane, ...
Double stars are stars that appear to be near each other in the sky, but if they're gravitationally bound together we call them binary stars. Many stars are actually ...
While Jupiter is nowhere near massive enough to initiate fusion in its core, there are even more massive objects out there that fall just short of that achievement ...
Before moving on from Jupiter to Saturn, we're going to linger for a moment on Jupiter's moons. There are 67 known moons, and 4 huge ones that we want to ...
In which John Green, Hank Green, and Emily Graslie teach you about what happened in the Universe after the big bang. They'll teach you about cosmic ...
In today's Crash Course Astronomy, Phil takes a look at the explosive history of our cosmic backyard. We explore how we went from a giant ball of gas to the ...