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2.7: Telescopes

Difficulty Level: At Grade Created by: CK-12
Atoms Practice
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Practice Telescopes
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Title Page/Overview

Credit: Clinton Steeds
Source: https://flic.kr/p/yyMZn
License: CC BY-NC 3.0

SC.1.E.5.1 Observe and discuss that there are more stars in the sky than anyone can easily count and that they are not scattered evenly in the sky.

SC.1.E.5.3 Investigate how magnifiers make things appear bigger and help people see things they could not see without them.

Objects can be seen if light available to illuminate them or if they give off their own light.(1-PS4-2)

Some materials allow light to pass through them, others allow only some light through and others block all the light and create a dark shadow on any surface beyond them, where the light cannot reach. Mirrors can be used to redirect a light beam. (Boundary: The idea that light travels from place to place is developed through experiences with light sources, mirrors, and shadows, but no attempt is made to discuss the speed of light.) (1-PS4-3)

Grade Readability 2.7 (430L)

Page 1

Look up at the night sky. You can see hundreds of stars. There are too many to count. Most of these points of light are stars like our Sun. A few are planets. Planets are within our solar system. They orbit the Sun like the Earth. Compared to stars, planets are close. The stars are very, very far away.

Credit: Gemma Stiles
Source: https://flic.kr/p/ffJqQT
License: CC BY-NC 3.0

Page 2

Planets do not produce their own light. We see planets because they reflect light. Stars produce their own light. Some stars are bigger than our Sun. Some stars are smaller. Our Sun is an average size star.

Credit: Brian Neudorff
Source: https://flic.kr/p/bnm7SY
License: CC BY-NC 3.0

Page 3

Why does the Sun look so big? Objects that are close look large. Objects that are further away look smaller. The Sun looks big because it is close.

Credit: Public Domain
License: CC BY-NC 3.0

Light is the fastest thing in the universe. Even light can take many years to travel from a star. Light from the Sun takes less than ten minutes to get to Earth. When you look at stars, you look into the past.

Page 4

Scientists use telescopes to study the night sky. Telescopes don not make stars look bigger. They are too far away. Instead, they allow more light to be collected. Telescopes let us see more stars. Even with a telescope, stars are only points of light.

Credit: Ryan Wick
Source: https://flic.kr/p/6gUTqU
License: CC BY-NC 3.0

Page 5

Galileo built the first telescope in 1608. His first telescope used a lens. Lenses bend, or refract, light. Many people still use this type of telescope. They help us see close objects better. You can see the surface of the Moon. You can see Saturn’s rings. Are planets close to us?

Compared to stars, they are close.

Credit: NASA/JPL/Space Science Institute
Source: https://flic.kr/p/7ayNkz
License: CC BY-NC 3.0

Page 6

Newer telescopes use mirrors. Mirrors allow more light to be collected. This helps us see more stars. Most scientists use telescopes with mirrors.

Source: https://flic.kr/p/5B2Qum
License: CC BY-NC 3.0

Page 7

Large telescopes are placed on mountain tops. Why do you think that is? It is because Earth’s atmosphere distorts light. On a high mountain there is less air to look through. Can you think of a better place to put a telescope?

Credit: CK-12 Foundation
License: CC BY-NC 3.0

Telescopes on top of Mauna Kea in Hawaii.

Page 8

What is higher than a mountain? Some telescopes are in outer space. In space there is no distortion. The Hubble Space Telescope has been in orbit for more than 20 years. It sends back the very clear images. You may have seen some of these images. The Hubble helps scientists find answers to questions.

Source: CK-12 Foundation; License
License: CC BY-NC 3.0

(a) The Hubble Space Telescope orbits Earth at an altitude of 589 km (366 mi). It collects data in visible, infrared, and ultraviolet wavelengths. (b) This starburst cluster is one of the many fantastic images taken by the HST over the past two decades.


electromagnetic radiation

electromagnetic radiation

Energy transmitted through space as a wave.
electromagnetic spectrum

electromagnetic spectrum

The full range of electromagnetic radiation.


The number of wavelengths that pass a given point every second.


The shortest wavelength radio waves.
radio telescope

radio telescope

A radio antenna that collects radio waves or microwaves.
reflecting telescope

reflecting telescope

Telescopes that use mirrors to collect and focus light.
refracting telescope

refracting telescope

Telescopes that use convex lenses to collect and focus light.
space telescope

space telescope

Telescopes in orbit above Earth's atmosphere.


Horizontal distance from wave crest to wave crest, or wave trough to wave trough.

Image Attributions

  1. [1]^ Credit: Clinton Steeds; Source: https://flic.kr/p/yyMZn; License: CC BY-NC 3.0
  2. [2]^ Credit: Gemma Stiles; Source: https://flic.kr/p/ffJqQT; License: CC BY-NC 3.0
  3. [3]^ Credit: Brian Neudorff; Source: https://flic.kr/p/bnm7SY; License: CC BY-NC 3.0
  4. [4]^ Credit: Public Domain; License: CC BY-NC 3.0
  5. [5]^ Credit: Ryan Wick; Source: https://flic.kr/p/6gUTqU; License: CC BY-NC 3.0
  6. [6]^ Credit: NASA/JPL/Space Science Institute; Source: https://flic.kr/p/7ayNkz; License: CC BY-NC 3.0
  7. [7]^ Source: https://flic.kr/p/5B2Qum; License: CC BY-NC 3.0
  8. [8]^ Credit: CK-12 Foundation; License: CC BY-NC 3.0
  9. [9]^ Source: CK-12 Foundation; License; License: CC BY-NC 3.0


Difficulty Level:

At Grade


Date Created:

Feb 24, 2012

Last Modified:

Jan 30, 2016
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