Thermal infrared astronomy for the introductory laboratory.

This article focuses on the construction and educational use of low-cost infrared (IR) telescopes for introductory astronomy courses by adapting consumer-grade thermal infrared imagers, such as the Seek Compact Pro, with commercially available germanium lenses. It details how refracting and reflecting telescopes can be modified to observe celestial objects in the far infrared range (7.5–14 μm), enabling students to qualitatively explore temperature variations on bodies like the Moon and inner planets, which differ from visible-light observations. The study demonstrates practical laboratory exercises, including measuring magnification with an IR refractor and capturing thermal images of the Moon’s surface and phases of Venus, highlighting the complementary information IR astronomy provides. Limitations such as atmospheric absorption, camera sensitivity, and resolution are discussed, emphasizing that these IR telescopes are best suited for qualitative rather than quantitative temperature measurements. The article concludes that incorporating IR observations into undergraduate labs enriches understanding of the electromagnetic spectrum and planetary characteristics, paralleling professional astronomy’s multi-wavelength approach.