What can spectra tell us about temperature?

Stars are too far away (and too hot!) for a human to touch, yet we can measure their temperatures. Spectra make this possible! Let’s investigate how.

Measuring Earth’s Temperature

Spectrum Tool. The Target Object shows the spectrum of Earth’s emission as measured from space. Compare the Earth’s emission spectrum to the Comparison Object spectra models for different temperatures (in Kelvin).

Spectrum Notebook. In the Measuring Earth’s Temperature section, respond to these questions:

  1. Which model thermal spectrum best matches Earth’s emission spectrum?
  2. Convert the temperature you identified in question 1 from Kelvin to Celsius. What type of light does Earth emit?
  3. Given that Earth does not emit its own visible light, how are we able to see Earth from space? Hint: Recall from 1. Color that light can be emitted, reflected, absorbed, and transmitted.
Source 1:
Solar System — Earth Emission
Brightness
Full-intensity spectrum backgroundTransparency increases or decreases based on chart intensity, hiding or revealing the background
Left axis ticks
Spectrum intensity vs wavelength chart
Bottom axis ticks
Wavelength (Microns)
Source 2:
 
Brightness
Full-intensity spectrum backgroundTransparency increases or decreases based on chart intensity, hiding or revealing the background
Left axis ticks
Spectrum intensity vs wavelength chart
Bottom axis ticks
Wavelength (Microns)