Ch 28: Telescopes

About This Chapter

Watch video lessons to get an overview of telescopes used for astronomical purposes; learn how they work and about common factors that affect observations made using them. These lessons are just part of this college-level astronomy course.

Telescopes - Chapter Summary and Learning Objectives

Telescopes are powerful tools for observing astronomical bodies, including what they look like and how they behave. The video lessons here will introduce you to several kinds of specialized telescopes, how they work, and what kind of observations they're designed to make. You'll also learn about relevant concepts like the diffraction limit and adaptive optics. At the end of this chapter, you should be able to:

  • Talk about how a telescope works
  • Name three types of telescopes
  • Describe three kinds of astronomical observations
  • Understand what the diffraction limit is and what influences it
  • Understand how Earth's atmosphere and other factors affect astronomical observation

Video Objective
Light Sensors of Eyes and Cameras Understand the similarities in how human eyes and camera lenses focus light, as well as why cameras can have advantages.
Properties of a Telescope Describe key parts of a telescope and why they're important, especially the aperture.
Categories of Astronomical Observation Understand imaging, spectroscopy, and timing observation styles and how they're carried out.
Diffraction Limit: Definition and Factors Understand what the diffraction limit is, and discuss how the size of the telescope and wavelength of light can affect it.
Types of Telescopes: Radio, Reflecting & Refracting Telescopes Gain an understanding of common types of telescopes and their ideal uses.
Telescopes & the Electromagnetic Spectrum Discuss the electromagnetic spectrum with regard to Earth's atmosphere; learn why space telescopes are so important to astronomy.
Telescopes for Invisible Wavelengths vs. Those for Visible Light Learn about images made using X-rays and infrared light and the telescopes that make them possible.
How Earth's Atmosphere Hinders Astronomical Observations Discuss adaptive optics and why telescopes in space are essential for studying astronomy.

11 Lessons in Chapter 28: Telescopes
Types of Telescopes: Radio, Reflecting & Refracting Telescopes

1. Types of Telescopes: Radio, Reflecting & Refracting Telescopes

Learn about the different types of telescopes that astronomers use: X-ray, radio, gamma ray, reflecting and refracting. Learn what the differences are between them and what different things they show us about the universe.

Refracting & Reflecting Telescopes: Key Concepts

2. Refracting & Reflecting Telescopes: Key Concepts

This lesson will discuss some key terms and concepts relating to the refracting and reflecting telescope: primary mirror/lens, eyepiece, focal length, focal point, chromatic aberration, and achromatic lens.

Telescopes: Powers & Limitations

3. Telescopes: Powers & Limitations

This lesson will discuss some limitations and three important powers of the telescope: the light gathering power, resolving power, and magnifying power.

How Telescopes Form Images

4. How Telescopes Form Images

This lesson will explain to you the fundamental points of how images are formed in refracting and reflecting telescopes as well as why our eyes need telescopes to help us see distant objects.

How Telescopes Detect & Measure Light

5. How Telescopes Detect & Measure Light

This lesson will go over the numerous methods astronomers can use to detect and measure light, including photography, spectroscopy, photometry, and CCDs.

Different Kinds of Traditional Reflecting Telescopes

6. Different Kinds of Traditional Reflecting Telescopes

This lesson will discuss three major kinds of traditional reflecting telescopes and their major differences. These include the Newtonian, Cassegrain, and Schmidt-Cassegrain telescopes.

Major Forms of Telescope Mounts & Modern Mirrors

7. Major Forms of Telescope Mounts & Modern Mirrors

This lesson will discuss two major telescope mounts, the equatorial and altazimuth mount, as well as two modern kinds of telescope mirrors, the floppy and segmented mirrors.

Radio Telescopes & Interferometry

8. Radio Telescopes & Interferometry

This lesson will go over some key concepts related to radio astronomy. We'll cover what radio telescopes are, the basics of how they function, and what their disadvantages are compared to optical telescopes and how this is resolved.

Telescopes & the Electromagnetic Spectrum

9. Telescopes & the Electromagnetic Spectrum

This lesson will teach you about which forms of light can reach the ground and which cannot and how we overcome this problem. We'll go over the concept of seeing as well as why we send telescopes into space.

Telescopes & False Color Images

10. Telescopes & False Color Images

How do we 'see' invisible forms of light if they're invisible? What would happen if your eyes had the ability for X-ray vision here on Earth? This lesson will help answer these questions.

Factors That Hinder Astronomical Observations on Earth

11. Factors That Hinder Astronomical Observations on Earth

This lesson will discuss several important factors that affect the ability of someone using a telescope to see a celestial object clearly, including weather, dust, seeing, and light pollution.

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