Free classroom lesson · Grades 9–12 · 45 minutes
How do space telescopes see invisible light?
Compare Hubble and Webb to discover why astronomers observe beyond visible light.
Illustrative spacecraft artwork; not a live telescope or satellite feed.
Learning objectives
- Place visible and infrared light on the electromagnetic spectrum.
- Explain the need for infrared telescope cooling.
- Compare Hubble and Webb’s observational capabilities and locations.
Materials
- Notebook
- Electromagnetic spectrum diagram
- Optional calculator
Essential question
What can telescopes reveal when they detect light our eyes cannot see?
Explore the science
Visible light is a small part of the electromagnetic spectrum. Infrared light has longer wavelengths than visible red light and can reveal cool objects and distant galaxies.
Hubble observes primarily ultraviolet, visible, and near-infrared wavelengths from low Earth orbit. Webb specializes in near- and mid-infrared observations around the Sun–Earth L2 region.
Infrared instruments need protection from heat emitted by the telescope itself. Webb uses a large sunshield and additional cooling to detect faint infrared signals.
Investigation
- Draw the electromagnetic spectrum in order of increasing wavelength.
- Mark visible light, near-infrared, and mid-infrared on your diagram.
- Read the TransitSatellite Webb mission story and Hubble satellite engineering story.
- Explain why Webb’s sunshield is essential for infrared observations.
Discuss and reflect
- How can cosmic redshift make infrared astronomy useful?
- Why do astronomers still use both Hubble and Webb?
Self-check · No account required
Check your understanding
Why does the James Webb Space Telescope use a large sunshield?
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