UCF researchers say Pluto is a planet

CAPE CANAVERAL, Fla. (AP) - Researchers at the University of Central Florida are challenging Pluto's status as a dwarf planet, saying we've got it all wrong. 

In 2006, a global group of astronomy experts determined that a true planet must be the largest gravitational force in its orbit.  Since Neptune’s gravity influences Pluto, and Pluto shares its orbit with other objects, they demoted Pluto's status.  But some say this standard for classifying planets is not supported in the research literature.

The NASA spacecraft New Horizons in 2015 became the first spacecraft to visit Pluto.  It has spotted its next target on the outskirts of our solar system -- a tiny icy world known as Ultima Thule.   Ultima Thule is minuscule by comparison, an estimated 20 miles (30 kilometers) across. Scientists were surprised New Horizons could detect it from 100 million miles (155 million kilometers) out.