... By Michelle Thaller (Spitzer Space Center) . ... The Hottest Planet . ... Figure 1: Planets are much easier to see in infrared light, where at least they give off their own light instead of being totally swamped by their parent star. ... Not only was Spitzer able to isolate light from these planets, but by using its infrared spectrograph, Spitzer was also able to sample the chemistry of these distant planets and get a good estimate of their temperatures. ... The Spitzer Space Telescope . ...