Halloween Fireball Meteor

The bright fireball meteor that plunged down through the atmosphere over Alaska on Halloween night 1978 appears to be typical of others sighted elsewhere around the world. Trick-or-treaters and other night travelers reported that the event occurred near 6:15 p.m. Alaska Standard Time.

The meteor was probably first seen near altitude 100 miles (150 km). Reports from Black Rapids, Big Delta, Healy, Tok and Fairbanks suggest that the meteor was traveling nearly straight down. If it struck the earth, the point of impact appears to be south of Delta, north of Black Rapids, well west of Tok and well east of the Fairbanks area. Many persons reported that the fireball appeared to land nearby. Such reports occur because the human eyes are unable to distinguish distance to an object seen in the sky, but it seems that the human brain assumes that a moving bright light must be nearby. This is why reports of angle are so valuable, and why estimates of distance to objects in the sky are essentially useless.

As is typical of fireball meteors observed at night, this one was variable in color, mostly white, but blue, green, yellow and orange were reported. The change in color is caused partly by the slowing down of the meteor as it plows through the air and partly by the variable burning of the different elements of which the meteor is composed. By the time the meteor reaches terminal velocity--typically not faster than 300 meters per second or 1000 feet per second--the meteor no longer glows. This apparent burnout usually occurs several miles to several tens of miles above the ground. Repeated flaring up and breaking up into fragments are common occurrences. Apparently, only a small fraction of observed fireball meteors yield findable meteorites at the ground.

Booming and hissing noises associated with the Halloween night fireball were heard in the vicinity of Big Delta and Black Rapids. Similar noises are frequently reported within 40 or 50 miles of a fireball meteor's trajectory. The booming noises are analogous to the sonic boom of a high-speed aircraft; the hissing noises are unexplained. The Geophysical Institute's seismograph station at Black Rapids recorded the sonic boom at 6:23 p.m., several minutes after the meteor was seen.