Image-processed radio map of the Whirlpool Galaxy (M51), made at the 21 cm wavelength with the Very Large Array (VLA) radio telescope in New Mexico. At a distance of 20 million light years, M51 has well-defined spiral arms which are clearly visible in this map. The upper arm is disturbed by the gravitational pull of M51's companion galaxy, NGC 5195, which is the bright red & yellow spot near the top. The bright red spot at centre left is a star between Earth & M51. The colour coding runs from red for highest radio emission, through yellow, green, pale blue & dark blue to purple for the lowest emission.