It's an infrared telescope whose main mission finished in 2009 when it ran out of the coolant that's needed to keep it at an operating temperature. However one of the instruments is still functioning and continues to provide valuable data. The mission was renamed the Spitzer Warm Mission and redirected to its current capabilities.
The telescope was named in honor of Lyman Spitzer, an astronomer who had promoted the concept of space telescopes in the 1940s.
A startling picture of the Helix Nebula from Spitzer Space Telescope data. The nebula is about 700 light years away in the constellation Aquarius. The white dwarf star is visible in the center - it's what remains of a sunlike star after it ran out of nuclear fuel.
The bright red glow immediately around it is probably the dust kicked up by colliding comets that survived the death of their stellar host.
Three images of the Sculptor Galaxy from the Spitzer Space Telescope during its "cold" mission, i.e., before the coolant ran out. The largest of the three images is a composite of the two smaller ones.
The galaxy is 11.4 million light years away and is a feature of the southern sky. However it can be seen low in the sky in the northern hemisphere - it was discovered in 1783 by Caroline Herschel from the south of England. The Sculptor Galaxy (NGC 253) is a starburst galaxy, i.e., one whose nucleus contains a region of copious star formation.
This image of spiral galaxy M81 is a composite. In the image Chandra X-ray Observatory data is blue, optical data from the Hubble Space Telescope is green, infrared data is from the Spitzer Space Telescope (shown in pink), and there is ultraviolet data from GALEX shown in purple.
The inset shows a close-up the Chandra image. The center of M81 is a supermassive black hole about 70 million times more massive than the Sun.