Astronomers use telescopes that detect radiation from different parts of the electromagnetic spectrum. This interactive explains which part of the spectrum various telescopes are able to view and the sources of radiation that they detect.
Astronomers use telescopes that detect different parts of the electromagnetic spectrum. Each type of telescope can only detect one part of the electromagnetic spectrum. Select a label for information about the telescope, which part of the spectrum it views and the sources of radiation it is able to detect.
Test your knowledge of this information with the Which telescope? online quiz. The activity Exploring with telescopes has suggestions on ways to use this interactive and quiz.
To use this interactive, move your mouse or finger over any of the labelled boxes and click to obtain more information.
Transcript
Radio telescope
Part of spectrum viewed: Radio (wavelengths a lot longer than visible light).
Location: On the ground, as most radio waves get through the atmosphere.
Sources of radiation:
- Many radio waves in space come from cold clouds of hydrogen gas.
- Most stars do not give off many radio waves.
Image: A composite image of the Whirlpool Galaxy, using radio and visible light wavelengths. The white is how the galaxies appear to optical telescopes – one giant spiral galaxy with a smaller one hanging off an arm. The Very Large Array radio telescope array sees a much bigger picture. © B. Saxton (NRAO/AUI/NSF) with data provided by J. Hibbard, CC BY 3.0.
Infrared telescope
Part of spectrum viewed: Infrared (wavelengths longer than visible light).
Location: In orbit, as most infrared is blocked by the atmosphere.
Sources of radiation:
- Stars give off infrared as well as visible light.
- Cool stars give off more infrared than visible light.
- Dust that has been heated gives off infrared.
- Infrared can pass through dust clouds.
Image: The Milky Way imaged by Spitzer. This infrared image shows what cannot be seen in visible light – cooler stars (blue), heated dust (reddish hue) and Sagittarius A-Star as a bright white spot in the middle. Image by NASA/JPL-Caltech/S. Stolovy (Spitzer Science Center/Caltech) and released into the public domain.
Optical telescope
Part of spectrum viewed: Visible light.
Location: On the ground, as visible light gets through the atmosphere.
Sources of radiation:
- Hot stars give off visible light.
- Light can be reflected from dust clouds.
- Dust clouds can block visible light
Image: Matariki star cluster. © Fraser Gunn.
Ultraviolet telescope
Part of spectrum viewed: Ultraviolet (wavelengths shorter than visible light).
Location: In orbit, as most UV is blocked by the atmosphere.
Sources of radiation:
- The hottest stars (very young or very old) give off the most UV.
Image: A UV telescope image shows the hot young stars around the Southern Pinwheel galaxy. Visible light would only pick up the white spiral galaxy at the centre of the image. Courtesy of NASA/JPL-Caltech/MPIA.
