Astronomy Picture of the Day

Explanation: Will the spider ever catch the fly? Not if both are large emission nebulae toward the constellation of the Charioteer (Auriga). The spider-shaped gas cloud on the left is actually an emission nebula labelled IC 417, while a smaller fly-shaped cloud off the image to the left is dubbed NGC 1931 and is both an emission nebula and a reflection nebula. About 10,000 light-years distant, both nebulae harbour young, open star clusters. For scale, the more compact NGC 1931 (Fly) is about 10 light-years across. The featured picture in scientifically-assigned, infrared colours combines images from the Spitzer Space Telescope and the Two Micron All Sky Survey (2MASS). Spitzer is celebrating its 16th year orbiting the Sun near the Earth.