No Planet X to mark the spot: the elusive Planet X has yet to be found, but astronomers have "spotted a veritable treasure trove of new celestial objects, consisting of a host of sparkling stars and relatively cool substellar objects called brown dwarfs....".

• Author: Braffman-Miller, Judith
• Position: Science & Technology

AS A CONSEQUENCE of the historic 1846 discovery of the beautiful blue ice giant Neptune--the outermost of the eight major planets from the sun--there was a great deal of speculation among astronomers that yet another planet might exist beyond its orbit, dwelling in dark secret in a region of our solar system that is very far from the golden light and comforting warmth of our star.

The search for this remote world, dubbed Planet X, began in the middle of the 19th century. Today, though, the astronomical community generally agrees that Planet X, as originally envisioned, does not exist, as astronomers have announced that, after searching through hundreds of millions of objects dancing across the sky, NASA's Wide-Field Infrared Survey Explorer (WISE) space telescope has turned up no evidence for the existence of Planet X.

However, a second study, also conducted by astronomers using WISE, was more successful in its quest. The second study revealed that WISE had spotted a veritable treasure trove of new celestial objects, consisting of a host of sparkling stars and relatively cool substellar objects called brown dwarfs, which are "failed stars."

"We're finding objects that were totally overlooked before," comments Davy Kirkpatrick, a member of NASA's Jet Propulsion Laboratory Infrared and Processing Analysis Center team at the California Institute of Technology. He is lead author of the second study. Both studies were published in the March issue of Astrophysical Journal.

WISE was put into hibernation when it successfully completed its primary mission in 2011. However, in September 2013, it was reactivated and renamed NEOWISE, and assigned a new mission--to aid NASA in its efforts to spot the threatening population of potentially highly destructive near-Earth objects (NEOs) that might be on a collision course with our planet. The NEOWISE mission also was assigned the task of characterizing previously identified asteroids and comets in order to better understand their compositions and sizes.

The possible existence of Planet X constitutes one of the most enticing mysteries of modern astronomy. Indeed, Planet X has inspired many strange, imaginative, and rather bizarre doomsday scenarios, such as the infamous, much dreaded, and wildly disturbing Mayan Doomsday that was scheduled to destroy our planet on Dec. 21, 2012.

There is great wonder surrounding Planet X--it presents the haunting possibility that there may be a giant world lurking somewhere...