By The Associated Press

FLAGSTAFF - The northern Arizona observatory where Pluto was discovered is showing off its newest instrument.

Lowell Observatory and science cable giant Discovery Communications are unveiling a $53 million telescope that will help build on the observatory's major astronomical finds. Those include Pluto in 1930, the rings of Uranus and the first evidence the universe is expanding.

The so-called Discovery Telescope has a 4.3-meter mirror, making it the fifth-largest in the continental United States.

The first light images taken with the telescope will be shown at a private gala Saturday in Flagstaff. The keynote speaker is Neil Armstrong, the first man to walk on the moon.

The Discovery Channel has been documenting the path to the telescope's unveiling and is set to air a feature on it in early September.