Washington ? The moon has a strange but real pull on the Earth, its oceans and the human psyche, and early Sunday morning its tug will be a tad stronger than usual.

At 6:18 a.m. CDT Sunday, the moon, sun and Earth will array in a straight line, a phenomenon called syzygy, which happens twice a month. But this time, the syzygy coincides with the moon being at its closest point to the Earth for the month and nearly the year, a condition called perigee. In addition, the moon will be parked pretty much over the equator, pulling at Earth’s bulging waistline.

Those three factors together mean the moon will give a little extra pull at ocean tides and even the crust of the Earth, scientists say. This happens only every four years or so, according to the U.S. Naval Observatory.

While the moon will be pulling from 221,779 miles away, it will be unseen, because it’s a new moon the lighted lunar surface will be facing the sun. But even when you can’t see it, the moon figures prominently on Earth.

“The whole thing about the moon thing is that it’s spooky,” said Jack Horkheimer, director of Miami’s Space Transit Planetarium and host of the Public Broadcasting Service’s “Star Gazer” television show. “It’s deeply entrenched in our folklore. There are effects on tides. There are effects on certain kinds of animal lives. It’s a curiosity.”

Sometimes the moon’s triple phenomenon coincides with catastrophe, or breeds fear of one.

A British naval instructor noticed that this threesome was scheduled for Oct. 5, 1869, and warned of a terrible gale. Lo and behold, a hurricane hit the border area between Maine and New Brunswick, Canada, killing about 100 people, according to the Farmer’s Almanac. Scientists chalk it up to coincidence, because it happened during prime hurricane season.

On the other hand, in 1990, Iben Browning, a prominent lecturer, climatologist and self-taught earthquake expert, warned of an earthquake at New Madrid, Mo., or Tokyo because of the moon’s extra pull during syzygy. It didn’t happen.

This year’s syzygy-perigee-equator pull will increase high tides and decrease low tides by 2 to 3 inches, said Steve Gill, a top tidal expert at the National Ocean Service. That won’t mean much unless it coincides with Hurricane Lili, in which case it could cause more flooding or add protection from flooding.