Distant objects, like galaxies, are simply too far away for our eyes to see. Many forms of energy, like radio waves, are invisible and silent to us.

With technologies like telescopes and photography, we can see the universe that is hidden from our physical senses. We can see how stars are born, or reveal the rainbow of colours hidden in white light. Technology lets us extend our perception of reality to see our place within the solar system, galaxy and an infinite universe.

Everything with a temperature above absolute zero (-273° Celsius) emits electromagnetic radiation-including you! Generally, the hotter the object, the shorter the wavelengths it emits. Cool interstellar gas emits long infrared rays. The hottest stars emit short ultraviolet and X-rays. Astonomers use different types of telescopes, depending on what wavelength they want to see.
Distant objects, like galaxies, are simply too far away for our eyes to see. Many forms of energy, like radio waves, are invisible and silent to us.

With technologies like telescopes and photography, we can see the universe that is hidden from our physical senses. We can see how stars are born, or reveal the rainbow of colours hidden in white light. Technology lets us extend our perception of reality to see our place within the solar system, galaxy and an infinite universe.

Everything with a temperature above absolute zero (-273° Celsius) emits electromagnetic radiation-including you! Generally, the hotter the object, the shorter the wavelengths it emits. Cool interstellar gas emits long infrared rays. The hottest stars emit short ultraviolet and X-rays. Astonomers use different types of telescopes, depending on what wavelength they want to see.

© Canadian Heritage Information Network, 2003

James Clerk Maxwell Telescope (JCMT)

This giant dish collects submillimetre wavelengths JCMT converts extremely weak radio signalsinto new information about our Solar System, interstellar matter, and star birth in distant galaxies. The telescope's 15-metre dish is made of 276 adjustable aluminum panels held in place by a massive support structure. A giant Gore-Tex veil protects the dish from dust, wind and sunlight.

JCMT

© JCMT


Until the mid-1950s, visible light was our only source of information about the universe. Visible light is collected by optical telescopes like the kind you might have in your backyard.

But visible light is only a tiny portion of the electromagnetic spectrum. Astronomers use other kinds of telescopes to detect the invisible parts of the spectrum, such as near-infrared, microwaves, and radio waves. Planets, stars and galaxies all look different when "viewed" in each region of the spectrum.

The ability to detect invisible energy created an information explosion in astronomy. Radio telescopes first pointed us to distant quasars. Gamma ray telescopes revealed immense explosions known as Gamma Ray Bursters (GRBs). X-ray telescopes gave us new information about the Sun, neutron stars and exotic black holes.

Telescopes that gather longer waves, like radio waves, need a wider collecting surface. Radio dishes are often 100 metres or more across. A radio dish must be 10 000 times wider than an optical dish to "see" the same amount of detail.

The Crab Nebula is the remnant of a supernova explosion. Optical images show the ne Read More
Until the mid-1950s, visible light was our only source of information about the universe. Visible light is collected by optical telescopes like the kind you might have in your backyard.

But visible light is only a tiny portion of the electromagnetic spectrum. Astronomers use other kinds of telescopes to detect the invisible parts of the spectrum, such as near-infrared, microwaves, and radio waves. Planets, stars and galaxies all look different when "viewed" in each region of the spectrum.

The ability to detect invisible energy created an information explosion in astronomy. Radio telescopes first pointed us to distant quasars. Gamma ray telescopes revealed immense explosions known as Gamma Ray Bursters (GRBs). X-ray telescopes gave us new information about the Sun, neutron stars and exotic black holes.

Telescopes that gather longer waves, like radio waves, need a wider collecting surface. Radio dishes are often 100 metres or more across. A radio dish must be 10 000 times wider than an optical dish to "see" the same amount of detail.

The Crab Nebula is the remnant of a supernova explosion. Optical images show the nebula as it would appear to a human observer. X-ray images show the discarded shell of hot gas. Radio images reveal a magnetic field that draws radiation from electrons in the surrounding gas.

Light pollution makes it hard for astronomers to do their job. Any object astronomers want to see has to be distinguished from natural light sources such as the aurora borealis, sunlight reflecting off dust in space, and the Moon. Often they’re looking for very faint objects. Artificial light makes this even harder, and is one of the reasons that telescopes are often built out in the country or on mountains.

© Canadian Heritage Information Network, 2003

Crab Nebula

Optical image of the Crab nebula.

Palomar Observatory

© [Credit CU 33] Public Domain. Palomar Observatory


Crab Nebula

X-Ray Image of the Crab nebula.

NASA/CXC/SAO

© [copyright] [Credit CU 31] Public Domain, NASA/CXC/SAO


Crab Nebula

Radio Image of the Crab nebula.

VLA/NRAO

© [Credit CU 32] Public Domain. VLA/NRAO


Earth’s atmosphere screens out many kinds of radiation that astronomers need to study. Space telescopes catch the rays that never reach ground-based telescopes. Untroubled by clouds, light pollution, radio noise and the turbulent atmosphere, space telescopes "see" with astonishing clarity.

A space telescope doesn’t quit at sunrise. It can collect radiation from a patch of sky for days and nights on end, producing phenomenally detailed images of very faint objects.

Does this mean that ground-based telescopes are obsolete? Definitely not. They are much cheaper to build and have the advantage of size. With bigger mirrors, they can collect more detailed information. Astronomers often carry out research by combining ground-based and space observations.
Earth’s atmosphere screens out many kinds of radiation that astronomers need to study. Space telescopes catch the rays that never reach ground-based telescopes. Untroubled by clouds, light pollution, radio noise and the turbulent atmosphere, space telescopes "see" with astonishing clarity.

A space telescope doesn’t quit at sunrise. It can collect radiation from a patch of sky for days and nights on end, producing phenomenally detailed images of very faint objects.

Does this mean that ground-based telescopes are obsolete? Definitely not. They are much cheaper to build and have the advantage of size. With bigger mirrors, they can collect more detailed information. Astronomers often carry out research by combining ground-based and space observations.

© Canadian Heritage Information Network, 2003

Canada France Hawaii Telescope

The Canada France Hawaii Telescope sees in both optical and infrared wavelengths.

Odysseum (formerly Edmonton Space Sciences Center)

© Odysseum


Radio Telescope

The 26-metre Radio Telescope dish at the Dominion Radio Astrophysical Observatory in Penticton British Columbia.

National Research Council of Canada

© National Research Council of Canada


Space Telescope

The Hubble Space Telescope orbits 600 Kilometers above Earth. It provides stunning views of the Universe that cannot be made using ground-based telescopes or other satellites.

NASA

© NASA


James Webb Space Telescope

The James Webb Space Telescope will replace the Hubble Space Telescope by the end of the decade. This proposed 6-metre space telescope will be stationed more than a million kilometres from earth.

NASA

© US Gov public domain, NASA


Learning Objectives

The learner will:

  • Describe scientific and technological developments, past and present and appreciate their impact on individuals and societies
  • Describe the fundamentals of telescopes including function, types, and applications

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