Astronomy Picture of the Day

Explanation: Why does this Moon look so unusual? A key reason is its vivid red colour. The colour is caused by the deflection of blue light by Earth's atmosphere -- the same reason that the daytime sky appears blue. The Moon also appears unusually distorted. Its strange structuring is an optical effect arising from layers in the Earth's atmosphere that refract light differently due to sudden differences in temperature or pressure. A third reason the Moon looks so unusual is that there is, by chance, an airplane flying in front. The featured picturesque gibbous Moon was captured about two weeks ago above Turin, Italy. Our familiar hovering sky orb was part of an unusual quadruple alignment that included two historic ground structures: the Sacra di San Michele on the near hill and Basilica of Superga just beyond.