The great harmonic convergence this weekend will be of hordes of humans, but not of stars or the ancients.

While people meet on high rocks and hillocks around the country in a great psycho-astrological event, none of the astronomical events supposed to be occurring will actually occur. And none of the dates drawn from the Mayan calendar invoked to create the event is correct, according to amused scientists.

The free-form, two-day event has been billed by some as a spiritual Woodstock. What it appears to resemble most closely is another cultural artifact from the '60s, the "be-in," a free-form celebration capable of absorbing as many purposes as there are people in attendance.

According to the followers of Jose Arguelles, whose book on Mayan cosmology started the craze, the supposed convergence of astronomical events today and Monday presents a rare opportunity for earthlings -- by means of meditation, hand holding and humming -- to boost the world into a new age of peace and prosperity.

To that end, ceremonies are planned at dozens of "sacred" sites around the world, including the ruins at Machu Picchu in Peru, Mt. Shasta in northern California, the pyramids in Egypt, Japan's Mt. Fuji and the Black Hills of South Dakota.

"This has nothing whatsoever to do with rationality," said John B. Carlson, an astronomer and expert on the Mayan calendar who runs the Center for Archaeo-astronomy in Maryland. "It has to do with fun. Somebody will be making money; there will be a lot of parties, a lot of genetic material exchanged . . . .

"My own personal theory is that this is the 20th anniversary of the famous summer of love in Berkeley, and people are looking for something to do," he said.

Whether it is true or not by scholarly standards, most scientists are not faulting the convergence as a social event intended to bring peace to the world.

Arguelles is an art historian whose book, "The Mayan Factor," said the Mayans -- people of Mexico and Central America whose civilization peaked about 1,000 years ago -- were aliens from outer space. He also wrote that the Mayan calendar had a great cycle, starting in 3113 B.C. and ending in 2012, when earthlings will again be in contact with aliens.

He wrote that today, Aug. 16, 1987, will begin the last 25-year minicycle before the end of the great cycle.

Arguelles' theory is that the presence of "galactic beams" of psychic energy coincides with dates on the Mayan calendar and that other astronomical events should attend the last shift of the "galactic beam" through which Earth is passing.

Unfortunately, Arguelles got the dates wrong.

According to Carlson, the Mayan cycle actually began in 3114 B.C., not 3113, and the Mayans calculated their shorter cycles, or "catuns" (pronounced caTUNES), in stretches of less than 20 years, not 25 years.

And while the Mayans did a pretty good job of calculating the length of a year, they apparently had no concept of Earth as a planet or the stars as celestial "bodies," Carlson said. Their cosmology was rather earthbound, drawn in local landscapes rather than on cosmic canvas.

As for the heavenly passages, Leroy Doggett of the U.S. Naval Observatory checked the charts.

One suggestion was that Mars, Venus and Mercury would all line up behind the sun on Aug. 16.

"They don't," Doggett said. After searching a bit, he found some interesting events with those planets, although they will occur too late to meet Arguelles' harmonic schedule. On Thursday, Mercury will reach "superior conjunction" with Earth; that is, it will be precisely opposite Earth on the other side of the sun.

On Aug. 23, the same will happen with Venus, and on Aug. 25, Mars will be superiorly conjoined.

Another event convergence participants predict is a "grand trine" of planets -- an astrological passage of great significance in which three planets are momentarily exactly 120 degrees apart in the sky.

"Well, you'd have to work pretty hard to make the numbers fit," Doggett said. Jupiter will be at 30 degrees. But at the next expected niche, 150 degrees, there is nothing: Mars is at 146, Venus 141. For the third position to be right, a planet should be at 270 degrees: Uranus will be at 263, Neptune at 275.

The new moon won't be until Aug. 24, so that's out.

No matter, Carlson said. "After all, this is Rorschach archeology. All you have to do is take a look and say, 'What does it mean to me?' "

No one seems to know how many people will participate in the event. "New Age" tour agencies have been busy in recent weeks organizing trips to the more farflung sites. And, as of yesterday, thousands were reported to be heading for New Mexico's Chaco Canyon. At California's Mt. Shasta, a park spokesman said that the number of visitors was about 700 higher than normal but dismissed reports that rangers had closed the park because of crowding.

But most of those planning to observe the two-day event around the nation say that its pseudo- scientific underpinnings are far less important than the opportunity to gather and express vague but heartfelt hopes for what they call "planetary purification."

"I don't know what's going to happen," said Megan Byam, a legal secretary from Queens and an organizer of this morning's meditation in Central Park. "But what I'd like to see is a more peaceful world. I'd like to see people come into their own, to see that they have the power to create their own lives."

H.N. Malony, psychology professor at Fuller Theological Seminary in Pasadena, Calif., said the event is not so much astronomical as social, like many others in which people have reached out for utopia. "There is a perennial hope for utopia. In this case, they hope that if 144,000 people get together and hum, peace will come," he said. "And of course the other side: There is a wish for catastrophe, the end of the world, if you don't succeed in getting 144,000 people."

The event and the many religious or quasi-religious groups collecting around it are in keeping with the history of the 20th century.

There has been a great proliferation of religious or quasi-religious groups in the United States since 1900, Malony said. "They have gained a foothold as never before. Or at least they are getting more publicity than ever before."

People have talked about recent movements, especially Christian movements, as a "return" to a religious America, he said. But actually in recent years, far more Americans have become members of churches or religious groups than in the past. At the turn of the century, only 30 percent of Americans had a religious affiliation, he said. In recent decades, the percentage has been double that. People have joined not just "mainstream" religions, but have created many others. "We just have had more openness. The society has been open enough to accept this kind of thing, and not to disparage the idealism of these people," Malony added.

In Washington, an organization called Washington Peace Celebration will gather at dawn today at 16th and Buchanan streets, and move to the Washington Monument for a meditation ceremony later in the day. There will also be ceremonies at several ashrams and yoga centers around the city, and at Browns Chapel Field in Reston. Fairfax County police in Reston said no one had arrived yesterday afternoon, but they were expecting people as early as midnight.

Unlike the tightly organized and promoted "Hands Across America" project, planning for the harmonic convergence has been decentralized. Publicity has been through word of mouth, or in hundreds of the newsletters and magazines -- most of them concerned with self-help, holistic medicine or mysticism -- that have proliferated in this decade.

In New York City, this morning's dawn meditation in Central Park has been organized through a private telephone network. The money to pay for the park permit was raised by passing a hat at a meeting in Greenwich Village. Organizers say they don't know whether to expect 50 or 5,000.

The event has proven an irresistable target for lampoonists. Harmonic convergence has appeared in the cartoon strip "Doonesbury" as "moronic" convergence. A comedian on the David Letterman show recently predicted that at the peak of planetary confluence, singer Marilyn McCoo would begin to orbit Earth seven times. McCoo, a member of the singing group "The Fifth Dimension," put the song "The Age of Aquarius" on the pop charts.