21.0 Beyond the Solar System

Introduction

To infinity and beyond!

Astronomy has advanced by leaps and bounds in the past few decades. Tools like the Hubble Space Telescope have allowed astronomers to see and understand things that they'd never even dreamed of. As recently as a century ago, no one knew that there was anything out there beyond our galaxy. Now we can see fantastic images of pinwheels, sombreros, towers, and many other shapes. In this chapter we will explore a tiny bit of what is beyond our solar system and even beyond our galaxy. The questions asked by the scientists who study these features are often profound: How did the universe begin? How will it end? Are we alone?

Chapter Outline

Chapter Summary

Summary

Stars have a life cycle that begins with birth, goes through middle age and ends in some sort of death. The exact path and the exact result depends on the size of the star. We can see different types of stars in the sky; they vary by size and brightness, which is how they are classified. Stars cluster in galaxies, which are fantastic structures in the sky. Our own Sun and solar system lies within an arm of a spiral galaxy, the Milky Way. Scientists have used observations, measurements, and mathematical calculations to hypothesize an origin for the universe, known as the Big Bang. These scientists continue to learn new things about the universe. For example, dark matter and dark energy have only recently been discovered.