This is the epic story of the stars, and how discovering their tale has transformed our own understanding of the universe. Once we thought the sun and stars were gods and giants. Now we know, in a way, our instincts were right. The stars do all have their own characters, histories and role in the cosmos. Not least, they played a vital part in creating us. There are old, bloated red giants, capable of gobbling up planets in their orbit; explosive deaths - supernovae - that forge the building blocks of life; and black holes, the most mysterious stellar tombstones. And, of course, stars in their prime, like our own sun. Leading astronomers reveal how the grandest drama on tonight is the one playing above our heads.
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. More massive stars like the Sun live shorter lives. They fuse hydrogen into helium, and eventually helium into carbon (and also some oxygen and neon). When this happens they expand, get brighter, and cool off, becoming red giants. They lose most of their mass, exposing their cores, and then cool off over many billions of years.
12m • 2015 • Crash Course Astronomy
Today Phil explains that YES, there are other planets out there and astonomers have a lot of methods for detecting them. Nearly 2000 have been found so far. The most successful method is using transits, where a planet physically passes in front of its parent star, producing a measurable dip in the star’s light. Another is to measuring the Doppler shift in a star’s light due to reflexive motion as the planet orbits. Exoplanets appear to orbit nearly every kind of star, and we’ve even found planets that are the same size as Earth. We think there may be many billions of Earth-like planets in our galaxy.
11m • 2015 • Crash Course Astronomy
Look up at the night sky, and you see countless shining stars. Our galaxy has 100 billion of them. Astronomers are now hunting for clues that will reveal "the first star" that transformed the ancient universe and led to the creation of everything that followed: galaxies, planets and life itself.
50m • 2014 • Cosmic Front