An artist's rendition of the HD 7924 planetary system — just 54 light-years away from Earth — shows newly discovered exoplanets c and d, which join Planet b. Karen Termaura, BJ Fulton/UH IfA hide caption

itoggle caption Karen Termaura, BJ Fulton/UH IfA

Saturn has a rocky surface, but it's deep beneath the clouds. That makes it hard to tell exactly how long the day is. NASA hide caption

itoggle caption NASA

Planet: bottom of a glass containing half and half, water, food coloring. Moons: bottom of a glass containing coconut milk, water, food coloring. Stars: salt, cinnamon, baking powder, Tums. Navid Baraty hide caption

itoggle caption Navid Baraty

Stars over the Cerro Tololo Inter-American Observatory in Chile. Sheppard and Trujillo used the new Dark Energy Camera (DECam) on a telescope there to find the distant dwarf planet 2012 VP 113. Reidar Hahn/Fermilab hide caption

itoggle caption Reidar Hahn/Fermilab

This diagram for the outer solar system shows the orbits of Sedna (in orange) and 2012 VP113 (in red). The sun and terrestrial planets are at the center, surrounded by the orbits (in purple) of the four giant planets — Jupiter, Saturn, Uranus and Neptune. The Kuiper belt, which includes Pluto, is shown by the dotted light blue region. Scott S. Sheppard/Carnegie Institution for Science hide caption

itoggle caption Scott S. Sheppard/Carnegie Institution for Science

Kepler-22b, seen in this artist's rendering, is a planet a bit larger than Earth that orbits in the habitable zone of its star. Some researchers think there might be "superhabitable" worlds that may not resemble Earth. NASA/Ames/JPL-Caltech hide caption

itoggle caption NASA/Ames/JPL-Caltech

This illustration shows the relative sizes of the habitable-zone planets Kepler-22b, Kepler-69c, Kepler-62e, Kepler-62f and the Earth. NASA/Ames/JPL-Caltech hide caption

itoggle caption NASA/Ames/JPL-Caltech

An illustration shows how the planet Kepler-36c might look from the surface of the neighboring Kepler-36b. David Aguilar/Harvard-Smithsonian Center for Astrophysics/NASA hide caption

itoggle caption David Aguilar/Harvard-Smithsonian Center for Astrophysics/NASA