LEARNING OBJECTIVES By the end of this section, you will be able to: Much of astronomy is motivated by a desire to understand the origin of things: to find at least partial answers to age-old questions of where the universe,…
LEARNING OBJECTIVES By the end of this section, you will be able to: How do we know the age of the surfaces we see on planets and moons? If a world has a surface (as opposed to being mostly gas…
LEARNING OBJECTIVES By the end of this section, you will be able to: The fact that there are two distinct kinds of planets—the rocky terrestrial planets and the gas-rich jovian planets—leads us to believe that they formed under different conditions.…
LEARNING OBJECTIVES By the end of this section, you will be able to: The solar system1 consists of the Sun and many smaller objects: the planets, their moons and rings, and such “debris” as asteroids, comets, and dust. Decades of observation…
LEARNING OBJECTIVES By the end of this section, you will be able to: If you’ve ever gone on a hike, you have probably been eager to see what lies just around the next bend in the path. Researchers are no…
LEARNING OBJECTIVES By the end of this section, you will be able to: Earth’s atmosphere blocks most radiation at wavelengths shorter than visible light, so we can only make direct ultraviolet, X-ray, and gamma ray observations from space (though indirect…
LEARNING OBJECTIVES By the end of this section, you will be able to: In addition to visible and infrared radiation, radio waves from astronomical objects can also be detected from the surface of Earth. In the early 1930s, Karl G. Jansky,…
LEARNING OBJECTIVES By the end of this section, you will be able to: After a telescope collects radiation from an astronomical source, the radiation must be detected and measured. The first detector used for astronomical observations was the human eye, but it…
LEARNING OBJECTIVES By the end of this section, you will be able to: Since Newton’s time, when the sizes of the mirrors in telescopes were measured in inches, reflecting telescopes have grown ever larger. In 1948, US astronomers built a…
LEARNING OBJECTIVES By the end of this section, you will be able to: Systems for Measuring Radiation There are three basic components of a modern system for measuring radiation from astronomical sources. First, there is a telescope, which serves as a…