The distant giant planet Uranus is seen to the lower left of a lunar eclipse on October 7th 2014. A lunar eclipse occurs as the Moon passes into the Earth's shadow. The red light is due to shorter wavelengths, such as blue light, being scattered more in the atmosphere than longer wavelengths such as red light. Lunar eclipses occur only at full Moon, and then only when the Earth and Moon are correctly aligned (about 2-3 times a year).