The sun has a global magnetic field, but also countless smaller fields trying to emerge from the star. (NASA)

Sunset backlights an immense thunderhead over Borrego Springs, California. (Dennis Mammana)

A large solar flare (white flash in the center) erupted on July 14, 2000 -- it is known to solar physicists as the Bastille Day event. (ESA/NASA)

A Caribbean reef shark cruises beneath the late afternoon sun near Bimini. (Grant Johnson)

A large proton storm blasts highly energized particles out from the Sun toward Earth at half the speed of light. (ESA/NASA)

In Iceland, the sun peeks above the horizon for a short visit around midday on the spring equinox. (Pekka Parviainen)

The Spirit rover captured this image of a Martian sunset beyond Gusev Crater. (NASA)

Sunlight can be distorted and reflected--literally bending around the rim of the Earth--as it passes through the atmosphere. (Pekka Parviainen)

A rare double rainbow hovers over Galway, Ireland. (Julie Deth-Rhoden Hutto)

A sun pillar rises atop the setting sun in the North Atlantic Ocean. (Mike Carlowicz)

Children in Maryland woke up early to observe the transit of Venus in June 2004. (Steele Hill)