Yale Astronomers Find New Minor Planet Between Neptune And Pluto

A new minor planet measuring about 400 miles in diameter and located between Neptune and Pluto in the outer rim of the solar system has been found by Yale astronomers.

Officially named 2000 EB173, the planet was discovered using a powerful telescope located at the CIDA observatory in Merida, Venezuela. In addition to Yale astronomers, the team included scientists from Indiana University and Venezuela’s University of the Andes.

Because of its small size, one quarter the size of Pluto, the planet is known as a “planetoid” or “plutino,” meaning “Little Pluto.”

“The significance of this finding? It’s just ‘Wow!’ After all these years we can still find something new in our solar system,” said Professor Charles Baltay, chairman of the Department of Physics at Yale University and leader of the group that made the discovery. “Some of it is luck. We looked in the right place. The other is the precision of our instrumentation.”

Baltay said the telescope used in making the observation encompasses 250 square degrees of sky in one night, compared to one tenth of one square degree with a more conventional telescope. The more powerful telescope is equipped with a digital camera and photographs any changes in the sky.

“Most of the stars in the sky don’t change night to night, or even century to century,” Baltay said. “However, planets in our solar system move very rapidly.”

He said the members of the Quasar Equatorial Survey Team (QUEST) were looking for quasars, supernovae and other variable objects when they found the plutino. It was detected through a computer-aided search of thousands of images recorded in a single six-hour period on the night of March 15. The tiny, reddish planet was scarcely moving - just 10 arc seconds per night - but was still fast enough to be recorded on the digital film.

Although many other objects have been recorded in the area known as the “Kuiper Belt” just outside Pluto’s orbit, none were as large as the new planetoid.

Baltay said it is customary that whoever finds a new object in the solar system is allowed to name it, but only after it has circled the sun twice. Unfortunately for Baltay, it will take 243 years for plutino to circle the sun just once.

Other Yale researchers involved in the discovery were David Rabinowitz, associate research scientists in the Department of Physics, Bradley Schaefer, assistant professor of physics and astronomy, now at the University of Texas at Austin, and Ignacio Ferrin of the University of the Andes.

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