An artist's illustration of Kepler-22b, a planet that circles its star in the "goldilocks" zone. Ames/JPL-Caltech/NASA/Getty Images hide caption

itoggle caption Ames/JPL-Caltech/NASA/Getty Images

In this rare image taken on July 19, 2013, the wide-angle camera on NASA's Cassini spacecraft has captured Saturn's rings and our planet Earth and its moon in the same frame. NASA/JPL-Caltech/Space Science Institute hide caption

itoggle caption NASA/JPL-Caltech/Space Science Institute

That little blue dot is how Earth will likely appear in a photo shot from a spacecraft that is studying Saturn. NASA/JPL-Caltech simulation hide caption

itoggle caption NASA/JPL-Caltech simulation

No Free Doughnuts, Even In Space: PayPal is announcing a project with SETI, aiming to solve issues around taking regular people — and commerce — into space. Here, an artist's rendering of a space hotel, from the Space Tourism Society. John Spencer/Space Tourism Society hide caption

itoggle caption John Spencer/Space Tourism Society

An artist's impression of one of the super-Earth's surrounding the star Gliese 667 about 22 light years from Earth. ESO/L. Calçada hide caption

itoggle caption ESO/L. Calçada

The famous Ring Nebula is shown here in striking detail, in a composite image made from images from NASA's Hubble Space Telescope and infrared data from telescopes on Earth. NASA, ESA, C.R. Robert O'Dell, G.J. Ferland, W.J. Henney and M. Peimbert hide caption

itoggle caption NASA, ESA, C.R. Robert O'Dell, G.J. Ferland, W.J. Henney and M. Peimbert