M51 - Whirlpool Galaxy in IR (up) and UV (middle)
IR and UV images combinated: IR = red, UV = green (down)
There are two galaxies in the field. M51 (NGC5194) and NGC5195 (left
from M51). What does the images tell about the galaxies? Centers of the
galaxies are reddish so they emit more in infrared than in ultraviolet.
Spiral arms of the M51 are greenish so they emit more ultraviolet than
infrared. If all parts of the galaxies emit as much IR and UV then all
parts of the image would be same greenish red.
Exposure time of the UV image is longer because the earths atmosphere
is more transparent in IR than in UV. Also the camera is more
sensitive to IR than to UV.
0,43m (17inch), f/4,5 with focal reducer
(Located to Spain)