Being almost 6 billion km from the Sun, the rock and ice-bound planet's surface must be terribly cold, colder than liquid nitrogen. Estimates place Pluto's surface at a cryogenically chilly minus 396 degrees Fahrenheit. That's cold enough for water ice to act like rock. But the warmer interior protected by miles of thick nitrogen, methane and carbon monoxide ices, and heated by radioactive rocks at the planet's core, may support a deep layer of liquid water-a Plutonian ocean. It's fun to speculate what life forms might have evolved in that Stygian sea.
Any future astronauts landing on Pluto will stand on the frontier of the solar system. They will see the dwarf planet's cratered moon Charon looming large in the sky. Inward, toward the Sun, our feeble home star will appear much like Venus does from Earth. There will be no warmth from its rays. Outward, the explorers will gaze into an immense gulf of interstellar space.
What's in the Sky: Check out Plaskett's Star, the most massive binary sun known. The primary masses at 40 suns, the companion about 60 suns; in the southeast after 7 p.m. The first week of February is a good for the planet Mars. On Jan. 29, Mars was at opposition (opposite the Sun). While not as bright as during other oppositions, Mars doubled in brightness since Dec. 1 Sirius an and Jupiter are brighter. Mars rises in the east after sunset. Star chart courtesy of J. Kirk Edwards.
Lou Varricchio, M.Sc., lives in Vermont. He was a former science writer at the NASA Ames Rseracg Center in California and is a member of theNASA/JPL Solar System Ambassador. He is the recipient of the U.S. Civil Air Patrol's Brig. Gen. Chuck Yeager Aerospace Education Achievement Award. Interested in a presentation about space at your school or organization? Call Varricchio at 388-6397 or e-mail him at: firstname.lastname@example.org