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 the Temperature of an Incandescent Light Bulb

Spectrum Tool. The Target Object shows the spectrum of an incandescent light bulb (where a metal filament is heated to such a high temperature that it glows). Compare the spectrum of the light bulb to the Comparison Object spectra models for different temperatures (in Kelvins).

Spectrum Notebook. In the Measuring the Temperature of an Incandescent Light Bulb section, answer this question:

  1. What temperature thermal spectrum best matches the incandescent light bulb?

Note: The y-values of these model spectra are not plotted on the same scale—they have been modified so they can all be plotted in the range of the tool. The key is to compare the overall shape of the curves, and most importantly, where the peaks are.

Source 1:
Lamps — Incandescent Bulb
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)
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