WASHINGTON -- The moon is drifting toward Earth in a slow but inexorable fall from orbit and if something doesn't give, mankind will perish when worlds that have existed side by side for billions of years collide -- possibly within the next five years!

NASA COMPUTER GRAPHIC shows moon slamming into Earth.

That's the word from astronomer Mark Crealer, who cites NASA sources as saying that "something is happening out there -- something that we don't understand and are absolutely powerless to stop."

And in an unusually pointed memo to President Bill Clinton, the space agency warned that "the collision of the moon and Earth will be preceded by devastating changes in our tides and weather in the very near future."

"We've got problems, big problems, and all we can do is wait for them to go away -- or get worse," said Dr. Crealer.

"Needless to say, President Clinton is gravely concerned.

"And a major fear is that people will panic long before we feel the direct physical effects of our drifting moon. From a purely scientific viewpoint, it is a fascinating -- if somewhat mysterious -- turn of celestial events," he added.

"The moon drifting in space defies scientific explanation."

NASA declined to comment on the expert's report, although a spokesman admitted that the space agency is monitoring the position of the moon "quite literally, around the clock."

Dr. Crealer said NASA noticed a change in the moon's position during a routine "sky scan" on March 31.

As every schoolchild knows, the moon's distance from the earth normally varies from a maximum of 254,000 miles to a minimum of 227,000 miles.

But now, for the first time in recorded history, the moon is a mere 224,000 miles away. And while that might not sound like much of a variance, astronomers agree it is "a potentially cataclysmic change or order in our solar system."

"Life as we know it is possible only because of the delicate positioning of Earth in relation to the sun," said Dr. Crealer.

"If the moon continues to drift closer to Earth, the gravitational imbalance will bring about dramatic and devastating changes in our tides and weather, causing floods, tornadoes, droughts, hurricanes and electrical storms unlike anything the world has ever seen.

"These conditions will certainly cause great distress and most likely, the collapse of civilization long before the moon collides with Earth."

According to NASA, the moon appears to be moving toward Earth at the wildly fluctuating rate of 6 feet to 900 miles a day. And while such erratic movement makes it impossible to predict the exact date when the moon and Earth will collide, most experts speculate that the disaster will occur within five years.

"On a 'high' note, most if not all of us will be dead long before the moon hits," Dr. Crealer said.