Most of the Washington area missed the show, owing to heavy cloud cover, but last night NASA scientists successfully detonated the first in a planned series of high-altitude explosions designed to study the Earth's magnetic field.

At 9:17 p.m. EST, the orbiting Combined Release and Radiation Effects Satellite (CRRES) released a small explosive canister containing a payload of barium metal over South America. The eruption, about 4,000 miles high, vaporized the barium, producing a greenish glow about one-third the size of a full moon, NASA officials said. On the East Coast, the flare was visible in the southwest sky at about 33 degrees above the horizon.

The release is part of a $170 million, year-long NASA/Air Force joint project. Approximately every other night between now and Jan. 25, the high-orbit CRRES is scheduled to eject a canister containing one of two metals -- barium or lithium -- over South America at altitudes ranging from 3,000 to 21,000 miles. Explosives in the canisters vaporize the metallic contents, creating colorful clouds hundreds of miles wide that will temporarily "paint" the lines of the planet's magnetic field. When gusts of solar particles do the same thing near the North Pole, the effect is known as the aurora borealis (the northern lights), or aurora australis in the south.

The barium releases produce a vapor cloud that changes from green to blue during the flare's 15-minute duration. Lithium discharges create a less bright but much larger red glow lasting approximately five minutes.

The next scheduled release "windows" for barium canisters are 10:32 and 11:12 p.m. EST Monday and 12:37 a.m. Tuesday. The CRRES may also release a large lithium canister between 3:06 and 4:58 a.m. Tuesday.

NASA scientists will choose one of the windows depending on weather conditions at the time, or they may abort the release if visibility is not adequate. Updated information can be obtained by calling a recorded message at NASA's Marshall Space Flight Center in Huntsville, Ala. The number is 1-205-544-5356.