The “peanut with jets”, comet Hartley 2, as photographed by the EPOXI craft during its closest approach on November 4, 2010.

The “peanut with jets”, comet Hartley 2, as photographed by the EPOXI craft during its closest approach on November 4, 2010.

Galaxy NGC 1365. Hubble Space Telescope, 1999.

Galaxy NGC 1365. Hubble Space Telescope, 1999.

Star clusters at the heart of the ARP 220 galaxy. Hubble Space Telescope, August 2002.

Star clusters at the heart of the ARP 220 galaxy. Hubble Space Telescope, August 2002.

Composite image of Saturn’s aurora. Hubble Space Telescope, January 2004.

Composite image of Saturn’s aurora. Hubble Space Telescope, January 2004.

A stellar jet in the Carina Nebula. Hubble Space Telescope, 2009.

A stellar jet in the Carina Nebula. Hubble Space Telescope, 2009.

This unusually shaped galaxy is known as Hoag’s Object. It is characterized by a yellow center of older stars being orbited by a blue ring containing new stars. Hubble Space Telescope, July 2001.

This unusually shaped galaxy is known as Hoag’s Object. It is characterized by a yellow center of older stars being orbited by a blue ring containing new stars. Hubble Space Telescope, July 2001.

Planetary nebula NGC 2440. The white dwarf at its center is one of the hottest known, with a surface temperature of 200,000˚C. Hubble Space Telescope, February 2007.

Planetary nebula NGC 2440. The white dwarf at its center is one of the hottest known, with a surface temperature of 200,000˚C. Hubble Space Telescope, February 2007.

Infrared image of the Andromeda galaxy. Wide-field Infrared Survey Explorer (WISE), February 2010.

Infrared image of the Andromeda galaxy. Wide-field Infrared Survey Explorer (WISE), February 2010.

Triton, Neptune’s moon. Voyager 2, 1989.

Triton, Neptune’s moon. Voyager 2, 1989.

The I Zwicky 18 galaxy is the “Dorian Gray” of the sky. It was previously believed to be a toddler galaxy within an universe considered to be an adult; it was later discovered to contain faint older stars, suggesting it formed at the same time as other galaxies. Hubble Space Telescope, 2005 and 2006.

The I Zwicky 18 galaxy is the “Dorian Gray” of the sky. It was previously believed to be a toddler galaxy within an universe considered to be an adult; it was later discovered to contain faint older stars, suggesting it formed at the same time as other galaxies. Hubble Space Telescope, 2005 and 2006.