On a bright, cold morning on 15th February 2013, a meteorite ripped across the skies above the Ural mountains in Russia, distintegrating into three pieces and exploding with the force of 20 Hiroshimas. It was a stark reminder that the Earth's journey through space is fraught with danger. A day later, another much larger 143,000 tonne asteroid passed within just 17,000 miles of the Earth. Presented by Professor Iain Stewart, this film explores what meteorites and asteroids are, where they come from, the danger they pose and the role they have played in Earth's history.
New discoveries have revealed thousands of exoplanets beyond the solar system. Some resemble earth enough that one could be a new home for humanity. Even with cutting-edge technology, finding the perfect one is the scientific challenge of the age.
New evidence is rewriting the history of our solar system, and using the latest discoveries and cutting-edge tech, experts are investigating if our cosmic neighborhood once featured oversized alien Earths and a second Sun.
Today we’re talking about our galactic neighborhood: The Milky Way. It’s a disk galaxy, a collection of dust, gas, and hundreds of billions of stars, with the Sun located about halfway out from the center. The disk has grand spiral patterns in it, formed by the traffic jams of stars and nebulae, where stars are born. The central region is shaped like a bar, and is mostly old, red stars. There’s also a halo surrounding us of old stars.
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.