X-ray, Optical & Infrared Images of Centaurus A
Centaurus A is the fifth brightest galaxy in the sky -- making it an ideal target for amateur astronomers -- and is famous for the dust lane across its middle and a giant jet blasting away from the supermassive black hole at its center. Cen A is an active galaxy about 12 million light years from Earth.
(Credit: X-ray: NASA/CXC/SAO; Optical: Rolf Olsen; Infrared: NASA/JPL-Caltech)

X-ray, Optical & Infrared Images of M81
M81 is a spiral galaxy about 12 million light years away that is both relatively large in the sky and bright, making it a frequent target for both amateur and professional astronomers.
(Credit: X-ray: NASA/CXC/SAO; Optical: Detlef Hartmann; Infrared: NASA/JPL-Caltech)

X-ray, Optical & Infrared Images of M51
M51 is another spiral galaxy, about 30 million light years away, that is in the process of merging with a smaller galaxy seen to its upper left.
(Credit: X-ray: NASA/CXC/SAO; Optical: Detlef Hartmann; Infrared: NASA/JPL-Caltech)

X-ray, Optical & Infrared Images of M101
M101 is a spiral galaxy like our Milky Way, but about 70% bigger. It is located about 21 million light yearsfrom Earth. X-rays from Chandra reveal the hottest and most energetic areas due to exploded stars, superheated gas, and material falling toward black holes. Infrared data from Spitzer shows dusty lanes in the galaxy where stars are forming, while optical data traces the light from stars.
(Credit: X-ray: NASA/CXC/SAO; Optical: Detlef Hartmann; Infrared: NASA/JPL-Caltech)

Unlabeled and Labeled 4 Panel Images
This quartet of galaxies comes from a collaboration of professional and amateur astronomers that combines optical data from amateur telescopes with data from the archives of NASA missions. Starting in the upper left and moving clockwise, the galaxies are M101 (the "Pinwheel Galaxy"), M81, Centaurus A, and M51 (the "Whirlpool Galaxy"). In these images, X-rays from Chandra are in purple, infrared data from Spitzer are red, and the optical data are in red, green, and blue. The two astrophotographers who donated their images for these four images -- Detlef Hartmann and Rolf Olsen -- used their personal telescopes of 17.5 inches and 10 inches in diameter respectively.
(Credit: X-ray: NASA/CXC/SAO; Optical (M101, M81, M51): Detlef Hartmann; Optical (Centaurus A): Rolf Olsen; Infrared: NASA/JPL-Caltech)