Photograph by Detlev van Ravenswaay, Picture Press/Alamy
Published June 1, 2012 At the same time, the moon will be at
perigee—the lunar orb's closest approach during its egg-shaped
orbit around our planet—creating an eclipsed "supermoon." Lunar
eclipses happen when the full moon, Earth, and the sun are lined
up so that the moon crosses through Earth's shadow. (See lunar
eclipse pictures.) "It's a very cool kind of thing to see. It
gives us an almost 3-D feeling for space that we don't normally
get," said Mark Hammergren, an astronomer at the Adler
Planetarium in Chicago. Coined in 1979, the term "supermoon" is
often used to describe a full or new moon that coincides with
perigee—something that happens about once a year, on average.
(Related: "Titanic Sunk by 'Supermoon' and Celestial
Alignment?") We don't see an eclipse with every full moon
because our natural satellite follows a tilted orbit around
Earth. This tilt also means that an eclipse can be full or
partial, depending on how much of the lunar disk fal