Guide to the Galaxy: all good travel guides need a map, and the team unveil the most detailed 3D map of the Milky Way ever produced. A map that reveals that there may be 50 per cent more stars in the galaxy than we previously thought.
American astronomer Neil deGrasse Tyson gives us a guided tour of the strangest stars we have ever observed, and we discover that the Milky Way may already be colliding with our neighbouring galaxy, Andromeda.
Guide to the Galaxy
A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxias, literally “milky”, a reference to the Milky Way. Galaxies range in size from dwarfs with just a few hundred million (108) stars to giants with one hundred trillion (1014) stars, each orbiting its galaxy’s center of mass.
Galaxies are categorized according to their visual morphology as elliptical, spiral, or irregular. Many galaxies are thought to have black holes at their active centers. The Milky Way’s central black hole, known as Sagittarius A, has a mass four million times greater than the Sun. As of March 2016, GN-z11 is the oldest and most distant observed galaxy with a comoving distance of 32 billion light-years from Earth, and observed as it existed just 400 million years after the Big Bang.
