You embark on a fantastic voyage throughout the Universe, starting in this lecture with a whirlwind tour of the course, which extends from phenomena in Earth's atmosphere to events at the farthest reaches of space and time.

Many stars are members of binary systems, in which two stars orbit a common center of mass. Our best estimates of how much mass stars have come from observations of binaries. We find that massive stars have far shorter lives than low-mass stars.

When the central temperature of a contracting cloud of gas grows sufficiently high, it becomes a star—a gigantic, controlled, thermonuclear reactor, fusing hydrogen into helium and maintaining a constant luminosity and size.

Solar eclipses also come in annular and hybrid varieties, reflecting the varying distance of the Moon from Earth. A famous total solar eclipse in 1919 provided observational evidence for Einstein's general theory of relativity.

Until recently, astronomers had no smoking gun to identify the precise location and cause of gamma-ray bursts. Now they have assembled an abundance of clues pointing to two separate mechanisms: the collapse of a massive star, and the merging of two neutron stars—in each case creating a black hole.

Astronomers obtain most of their information through the analysis of light. This lecture introduces the electromagnetic spectrum and the technique of spectroscopy, in which light is dispersed into its component colors, as in a rainbow.

Delving deeper into the nature of light, you explore the strange duality between electromagnetic waves (light waves) and particles (photons), which is a fundamental feature of quantum theory.

Though broadly similar to Earth, Mercury and Venus differ in detail. Mercury has a negligible atmosphere and is heavily cratered. Venus has an incredibly thick atmosphere and suffers from an extreme greenhouse effect that makes it intensely hot.