MISSILE FUMES OVER SOUTHERN CALIFORNIA: Yesterday evening, March 26th, sky watchers in southern California were surprised when they saw swirls of colorful gas looping through the sunset sky. "This colorful cloud, the kind we usually see after a rocket launch, was visible from our home near Joshua Tree National Park," reports Cathleen Armstrong of Pioneertown CA. "We rushed outside without a tripod and shot this image before the light faded entirely."

Image credit: Cathleen Armstrong of Pioneer, California

Daniel Wood saw the same display from 38,000 feet. "I fly for a major US airline," says Wood. "We were approaching San Diego just after sunset and I noticed some thin wispy clouds ahead over the ocean that appeared to be much higher than us. As the sun set, they began to get very colorful and iridescent--all the colors of the rainbow, but diffused over a large area."

Image credit: Daniel Wood flying 38000 ft above San Diego

"I asked air traffic control if there was a rocket launch at Vandenberg AFB, since sometimes they leave interesting contrails, and they said 'no.'"

Indeed, this was not a launch from Vandenberg, although many observers thought that it was. Instead, the clouds likely came from a military exercise: the test launch of a Trident II (D5) missile from a submarine off the coast of San Diego, which was scheduled for March 26-27.

What caused the pearly colors? Water droplets and bits of unburnt fuel from the missile's exhaust froze in the cold upper atmosphere. When high-altitude sunlight hit the icy crystals, they glowed pastel yellow, red and blue--a phenomenon known as iridescence. The clouds were seen as far away as Arizona.