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 astronomy. Ancient Greeks were able to find the size of the Earth, and from that the distance to and the sizes of the Moon and Sun. Once the Earth/Sun distance was found, parallax was used to find the distance to nearby stars, and that was bootstrapped using brightness to determine the distances to much farther stars.
The Universe is a magnetic minefield, with cosmic bombs detonating everywhere. Our own Sun regularly spits out lethal and spectacular flares, capable of battering our power and communications systems here on Earth, and that's just the tip of the iceberg. Far out in space, spinning star systems crackle and explode, magnetic monsters rip worlds apart, star-quakes shoot out beams of devastating energy, and galactic flamethrowers fire gamma-rays half way across the Universe. Scientists are only now beginning to comprehend the true variety of the Universe's arsenal. As we uncover the most dangerous megaflares in the cosmos, the question is, will we find Earth in the firing line?
43m • 2012 • How the Universe Works
The story of how we discovered Dark Matter and what we do and don't know about this mysterious substance. Did Vera Rubin discover the glue holding galaxies together? What composes dark matter? What are Dark Stars and what is super symmetry, the potential answer to the questions around Dark Matter?
49m • 2014 • Cosmic Front
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 explore in greater detail. Ganymede is the largest - larger, in fact, than any other moon in the solar system and the planet Mercury! Callisto, orbiting the farthest out, is smaller but quite similar to Ganymede in many ways. Io, meanwhile, is most noteworthy for its tremendous volcanic activity. There’s also water on Ganymede and Europa!
10m • Crash Course Astronomy
The Ship of the Imagination travels back in time to reveal 11th century Europe and North Africa during the golden age of Islam, when brilliant physicist Ibn al-Haytham discovered the scientific method and first understood how we see, and how light travels. Later, William Herschel discovers the infrared and the signature hidden in the light of every star, eventually unlocking one of the keys to the cosmos.
Black holes are one of the most destructive forces in the universe, capable of tearing a planet apart and swallowing an entire star. Yet scientists now believe they could hold the key to answering the ultimate question: what was there before the big bang?