Tunisia.Tunis · residents and U.S. diplomats see green clouds in the sky

On the night of July 13, 1969, many people in Tunis, U.S. embassy officials among them, saw two phenomena in the northern sky. The first was a greenish-blue circular cloud, roughly the size of the full moon, which appeared a few degrees west of the Pole Star and well below it with respect to the horizon. The second appeared a few degrees to the right of the Pole Star and higher above the horizon than the first: at first it looked like a star, then it "exploded," forming a greenish circular cloud that quickly became misshapen and spread across the sky. Some witnesses did not see the cloud phase of the second phenomenon and spoke only of short-lived bright lights.

The embassy reported it to Washington the next day, July 14 at 12:05 GMT (Greenwich Mean Time), in the unclassified telegram TUNIS 3293, under the subject "Tunisian firefall." The telegram was addressed to the State Department's Office of International Scientific and Technological Affairs (SCI), copied to NASA among others, and asked for it to be passed to the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts.

It was not the first report: the text says that what was seen on the 13th was "almost identical" to what the embassy had described in an earlier telegram, TUNIS 3222, and it ends: "Would appreciate knowing explanation which Smithsonian may have found for these phenomena." The U.S. National Security Agency (NSA) collection of UFO documents in which the telegram is kept does not include the reply.

A calculation of our own, based on the launch calendar of the time, points to an explanation that no published source puts forward. 314 kilometers north of Tunis, on the east coast of Sardinia, was the Salto di Quirra range, from which the European Space Research Organisation (ESRO) launched Skylark sounding rockets, scientific rockets that climb into the upper atmosphere and fall back. In July 1969 there was a campaign with four launches, all at dusk: July 5 at 19:45 GMT (mission S38/1, ionosphere), the 6th at 19:50 (S64/1, aeronomy), the 11th at 19:42 (S38/2, ionosphere) and the 13th at 19:41 (S64/2, aeronomy, with its highest point at some 280 kilometers). The last one coincides with the night of the telegram, and the earlier ones could explain why the embassy had already reported something similar.

The geometry fits the first phenomenon. Seen from Tunis, Salto di Quirra lies on a bearing of 351°, nine degrees west of north, which is where the witnesses placed it relative to the Pole Star. The second, "a few degrees" to the right of the Pole Star, lay east of north; the telegram does not say how many degrees. By our own calculation, to be seen there whatever was glowing had to lie east of the range, about 70 kilometers if "a few degrees" means 3° to 6°, and the sources consulted do not give the rocket's launch azimuth. From Tunis, the Pole Star stands about 37° above the horizon. A cloud 100 to 200 kilometers above Sardinia would be seen lower, at 16° to 31°, and a point at the rocket's maximum height higher, at about 40°.

At 19:41 GMT the Sun was 11° below the horizon in Tunis, so the ground was dark, but anything more than about 80 kilometers above Sardinia was still sunlit. That is exactly the condition sought by experiments that release chemical vapor clouds in the upper atmosphere: they are launched at twilight precisely so that the cloud glows against a dark sky. It has not been possible to confirm which substance the S64 payload carried, but ESRO had begun its program at Salto di Quirra with barium and ammonia clouds, and neutral barium glows greenish-blue.

Many people in Tunis, U.S. diplomats among them, saw the phenomenon, and the embassy itself treated it as a scientific curiosity: it spoke of neither UFOs nor saucers, used the word "firefall," asked an observatory for help and recorded that the phenomenon was recurring. The Smithsonian Observatory in Cambridge then ran a service devoted to recording short-lived phenomena (meteors, volcanoes, fireballs) and was the natural recipient. In March 1975, in the middle of the diplomatic crisis over the objects above Algeria (↗ Algeria), the same embassy cabled Algiers that there had been no recent UFO reports in Tunisia and that it could shed no light on what had been described.

If the rocket explanation is right, the case shows how the space science of the 1960s and 1970s left spectacular phenomena in the night sky that nobody on the ground knew how to interpret, because launches were not announced to the public of neighboring countries.

That explanation has three limits. The telegram does not give the time of the observation, only "evening July 13." It is not known for certain what the S64/2 payload released. And without the launch azimuth it cannot be checked that the second phenomenon, east of north, came from the same rocket. In its favor are the coincidence of date, direction of the first phenomenon, apparent height and twilight hour, and the fact that the phenomenon recurred in a month with several dusk launches, although the date of the earlier sighting is not known.