Amateur astronomers in the Northern Hemisphere are getting their best look at Mars in over a century as the red planet makes its closest approach to Earth in years.

"This is a rare chance for people to take a look at a world where humans may one day walk," said Susan Lendroth, spokeswoman for the Pasadena-based Planetary Society, which is sponsoring dozens of Mars Watch '88 public viewing parties and a formal observation program by amateur astronomers.Mars will be at its closest to Earth at 9:18 MDT Wednesday night, when the two planets will be 36.54 million miles apart, said astronomer Ed Krupp, director of Los Angeles' Griffith Observatory.

That's the closest the two planets have been since they were 34.92 million miles apart in August 1971 and closer than they will get until they approach within 34.65 million miles of each other on Aug. 27, 2003. They sometimes are as many as 248 million miles apart.

Because Mars now appears much farther north in Earth's skies than usual during such close encounters, views for Northern Hemisphere observers will be better than at any time since 1875 or until 2025, astronomers said.

"Mars will be so bright, some people might mistake it for an airplane before they realize it's not moving," said Bart Benjamin, head of Triton College's Cernan Earth and Space Center near Chicago, in a telephone interview Tuesday.

"It's not something you have to strain your eyes to see. After the moon, it's the brightest object in the night sky right now," Benjamin added, noting the planet has been an astral highlight for weeks and will continue as such.

Telescope views are very good for more than a month on either side of Wednesday night's close approach, and Mars will rise earlier in the evening in future weeks.

About 100 of the 500 amateur astronomers participating in the worldwide Mars Watch '88 observation program have sent more than 1,500 photographs and sketches of the planet to Jeff Beish and Dr. Donald Parker, official "Mars recorders" for a group named the International Mars Patrol.

It's now summer in Mars' southern hemisphere, and the southern ice cap extends only to 81 degrees south latitude, much smaller than during winter, when it sometimes stretches almost halfway toward the equator, Beish said by phone from Miami.

"The largest volcanoes can be identified by very experienced telescopic observers using large instruments," Beish said. "Sometimes I see Olympus Mons. That's the biggest one," three times taller than Mount Everest.

He said observers "are now seeing mountainous clouds. They are round or oval-shaped white puffs. They're around the known volcanoes."

Backyard astronomers in Japan, Italy, New Zealand and New Guinea also are seeing other Martian surface features now that dust has settled from a June dust storm that measured 4,800 miles long by 2,500 miles wide, Beish added.

"They are seeing features that they've never seen before," including several long, dark streaks that appeared recently, he said. "Mars changes from minute to minute. There's always something to discover."