Pluto, in theory, could take a hike

Danny Schellin, 9, a rising fourth-grader at Libertyville's Rockland Elementary School, sent Kids Ink these questions about astronomy:

"Can any planet move away from the solar system? Can the Sun's temperature change? Can there be another Sun in our solar system?

If we could jump into a time machine and travel billions of years into the future, it's possible that Pluto, with its erratic orbit, could spiral out of our solar system.

Geza Gyuk, director of astronomy at the Adler Planetarium in Chicago, said the probability is a long shot. "Pluto has been found to be chaotic with a time scale of millions of years. While it is unlikely, it is perhaps possible that Pluto could be ejected many billions of years from now."

Traveling back in time, though, astronomers believe that our solar system was chock full of planets. "During the early stage of the solar system there were probably tens if not hundreds of protoplanets, perhaps some even as large as Mars."

Gyuk said evidence can be found on many planets, including Earth. A Mars-sized object struck Earth when it was newly formed, splitting off a hunk that became the moon.

Jupiter's extra strong gravity might have catapulted those extra planets into space. "By now, some of the Earth's siblings may be on the other side of the galaxy, 50,000 light years away," Gyuk said.

The Sun's temperature is 11,000 degrees Fahrenheit. In the past few decades, the change has been extremely slight ­­- 1/40th of one percent. "On the thousands-of-years scale, the temperature may have changed as much as 10 to a couple of tens of degrees," Gyuk said.

Over billions of years, the Sun has become 70 percent brighter. Billions more years into the future the Sun's hydrogen fuel will be exhausted to the core. The Sun will become a huge Red Giant - extremely bright but not very hot. When all the fuel is used up, the Sun will collapse into a small White Dwarf, very hot and very tiny.

Astronomers haven't sighted another Sun in our solar system, and have even pointed telescopes half a light-year out to the edge of our solar system - that's half a trillion miles away. "A star as big and bright as the Sun we would see no matter where it was in the solar system. It would be the brightest star in the sky by far."

Gyuk said new telescopes that will become available within the next decade will rule out the possibility of dual or multiple suns. These strong telescopes could even site tiny Red Dwarfs, which are smaller than the Sun and less luminous, even though none are believed to exist in our solar system.

Want to know more about powerful planetary punches? The Adler Planetarium is now featuring the movie "Cosmic Collisions" which documents the constant bumper car motion of huge planetary impacts as well as tiny particles in space. For more details, see www.adlerplanetarium.org.

Check these out

The Vernon Area Public Library District in Lincolnshire suggests these titles on astronomy:

• "Telescopes," by James Barter

• "Will the Sun Ever Burn Out?" by Rosalind Mist

• "How Do We Know the Size of the Solar System," by Isaac Turiel

• "The Planet Hunters," by Dennis B. Fradin

• "The Sun and Other Stars," publisher: World Book

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