Composite image of petroglyphs on a boulder at a Hohokam site in southern Arizona and a view of Comet Hale-Bopp. The petroglyphs may depict the passage of a comet. © Images by Science Source.

The total lunar eclipse April 15, 2014 in the crystal clear night sky over La Silla Observatory, located on the southern outskirt of the Atacama Desert, Chile. © Images by Science Source.

Composite image of a group of amateur astronomers silhouetted against the stars of Cygnus, Vega-Bray Observatory, Benson, Arizona. © Images by Science Source.

Hoodoos rock formation, the Milky Way, and a shooting star in Goblin Valley, Utah. © Images by Science Source

A spectacular display of Aurora Borealis or the Northern Lights over a small traditional Sami village in Lapland, northern Sweden. © Images by Science Source.

One of the four 8-meter Very Large Telescopes (VLT) located in the European Southern Observatory (ESO) site on Cerro Paranal is photographed under starry sky of Atacama Desert in Chile. © Images by Science Source.

Star trails seen through a natural rock arch, Arches National Park, Utah. © Images by Science Source.

Composite image of lunar eclipse phases; all images taken in Dayton, Ohio on October 8, 2014. © Images by Science Source.

Nighttime view of the Large Binocular Telescope (LBT), Mount Graham, Arizona. The giant observatory combines two side-by-side 8-meter telescopes, making it one of the world's largest telescopes. © Images by Science Source.

Color enhanced engraving of various comets with dust tails from the 1600s to the 1800s, including Comet of 1680, Donatus Comet of 1858, Halley's Comet of 1835, Comet of 1741, and Comet of 1811. © Images by Science Source.

Outline of the constellation Orion drawn in blue against the night sky. © Images by Science Source.

An amateur astronomer looks through a dome-covered telescope in this composite photo. © Images by Science Source

Optical image of the Hale-Bopp comet seen over trees and the aurora borealis. © Images by Science Source.

Time-lapse view of Parkes radio telescope at night in New South Wales Australia. © Images by Science Source.

Illustration of the night sky over London, with the Milky Way on the far right, 1869. © Images by Science Source.

Crescent moon and milky way in the night sky. © Images by Science Source.

A teen girl observes through a large refracting telescope. © Images by Science Source.