The expanding universe is a complicated place. During inflation the universe expanded faster than light, but that's something that actually happens all the time, it's happening right now. This doesn't violate Einstein's theory of relativity since nothing is moving through space faster than light, it's just that space itself is expanding such that far away objects are receding rapidly from each other. Common sense would dictate that objects moving away from us faster than light should be invisible, but they aren't. This is because light can travel from regions of space which are superluminal relative to us into regions that are subluminal. So our observable universe is bigger than our Hubble sphere - it's limited by the particle horizon, the distance light could travel to us since the beginning of time as we know it.
There are Black Holes, and then there are Monster Black Holes -- containing several million to ten billion times the mass of our Sun! They've been discovered in the center of many galaxies. But they don't just absorb everything around them...in fact, they may be key to forming new galaxies.
Were "little green men" trying to contact us? Over 40 years ago, extremely constant pulses were detected reaching the Earth from outer space. It caused a great sensation. Using a radio telescope larger than a baseball field, scientists looked for the source of these signals and found - pulsars.
This is the complete story of NASA's Moon Missions, from Apollo 1 to Apollo 17, told for the first time using 4K and HD original footage taken by astronauts from the most iconic space voyages in history. The world famous Apollo missions are some of the greatest feats ever accomplished by man. With rare archive footage and unprecedented access to life on board the Apollo spacecrafts, this stunning one-hour special brings scientific history to life.
2015 • Astronomy
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 them including their luminosity, size, and temperature. The HR diagram plots stars’ luminosity versus temperature, and most stars fall along the main sequence, where they live most of their lives.