Ideas about time and space are explored in the changes that constellations undergo over time, the redshift and blue shift measured in interstellar objects, time dilation in Albert Einstein's theory of relativity, the designs of both Leonardo da Vinci and spacecraft that could travel near light speed, time travel and its hypothetical effects on human history, the origins of the Solar System, the history of life, and the immensity of space. In Cosmos Update, the idea of faster-than-light travel by wormholes (researched by Kip Thorne and shown in Sagan’s novel Contact) is discussed.
Einstein, Oppenheimer, and other physicists and astronomers wrestled with the concept of Black Holes. With relentlessly powerful gravitational pull, black holes suck in anything that comes near them, but do they? As the study of black holes progresses, science finds more mysteries than solutions.
Astronomers study a lot of gorgeous things, but nebulae might be the most breathtakingly beautiful of them all. Nebulae are clouds of gas and dust in space. They can glow on their own or reflect light from nearby stars. When they glow it’s usually predominantly red from hydrogen and green from oxygen, and when they reflect and scatter light it’s from massive hot stars, so they look blue. Stars are born in some nebulae, and create new ones as they die. Some nebulae are small and dense, others can be dozens or hundreds of light years across.
We begin our story about 13.7 billion years ago, when all the space, matter, and energy of the known Universe was locked up in a volume less than one trillionth of the size of the point of a pen.
Mercury is a deadly world, facing attacks from the sun, comets, and other planets, and even though it's the smallest planet in the solar system, it has a dangerous secret a dangerous secret that might one day threaten life on Earth.