The New Solar System Guide

“If we found Pluto today, we probably wouldn’t call it a planet.”
“Pluto is best understood as the largest known member of the Kuiper belt, a band of rocky, icy miniplanets that orbit the sun…stretching from beyond Neptune to a distance of nearly 5 billion miles.” More than 1000,000 objects may rest there, including others that may be the size of Pluto.
“Beyond the Kuiper belt lies the mysterious Oort cloud, a spherical shell that stretches to the boundaries of interstellar space and blasts its own ice balls towards the sun.” A few planets may be in there about the size of Mercury or even Mars.

Pluto: Discovered-February 18, 1930. Distance from the sun-ranges from 2.8-4.6 billion miles. Orbital period-249 years. Diameter-1,430 miles.

Sedna: Discovered-November 14, 2003. Distance from the sun-ranges from 7-90 billion miles. Orbital period-10,500 years. Diameter-800-1,100 miles.

2004 DW: Discovered-February 17, 2004. Distance from the sun-4.4 billion miles. Orbital period-250 years. Diameter-1,000 miles.

Ixion: Discovered-May 22, 2001. Distance from the sun-3.7 billion miles. Orbital period-250 years. Diameter-500 miles.

Quaoar: Discovered-June 4, 2002. Distance from the sun-4 billion miles. Orbital period-285 years. Diameter-800 miles.

2002 UX25: Discovered-October 30, 2002. Distance from the sun-4 billion miles. Orbital period-278 years. Diameter-580 miles.

Varuna: Discovered-November 28, 2000. Distance from the sun-4 billion miles. Orbital period-283 years. Diameter-560 miles.

2002 TX300: Discovered-October 15, 2002. Distance from the sun-ranges from 4 billion miles. Orbital period-283 years. Diameter-540 miles.

2002 AW197: Discovered-January 10, 2002. Distance from the sun-4.4 billion miles. Orbital period-327 years. Diameter-550 miles.

November 2004, Discover magazine V25, N11, pp 42-49