Answer to Question #305467 in Astronomy | Astrophysics for J17

Question

The electromagnetic spectrum contains various types of radiation with different properties. The James Webb Space Telescope is not like an optical telescope at home and does not capture visible light; instead, it observes the sky in the infrared spectrum.

Explain what infrared radiation is and answer the following questions: How is infrared radiation different from visible light? Why does the JWST observe infrared light, and what are the scientific advantages for astronomers?

Answer 1

Infrared radiation (IR), also known as just infrared, is a part of the electromagnetic spectrum with wavelengths ranging from 700 nanometers (nm) to 1 millimeter. Infrared waves are longer than visible light waves, but they are shorter than radio waves. Infrared frequencies, which range from around 300 Ghz to 400 THz, are higher than microwave frequencies but lower than visible light frequencies. The only distinction between visible light and infrared radiation is the difference in their wavelengths. By use of infrared light, the Webb telescope will be able to gaze further back in time than preceding telescopes, allowing astronomers to spot stars developing inside dust. Paul Geithner explains why the Webb telescope concentrates on infrared wavelengths. Infrared waves have longer wavelengths than visible light allowing infrared waves to penetrate through thick gases and dust areas in universe with much less absorption and dispersing. Thus, infrared radiation can expose things in the space that optical telescopes cannot view in visible light. Webb will reveal us features that no other telescope has seen before by scanning the galaxy at infrared wavelengths. We can only see the first stars and planets emerging after the Big Bang at infrared wavelengths. One advantage of seeing in the near-infrared spectrum is that dust is transparent to it. This is why an optic telescope will be unable to view a star obscured by dust, while a near-infrared telescope would register its radiation.