Every day, weather forecasters launch flotillas of balloons to measure conditions in all layers of the atmosphere. It's a routine operation. In fact, about the biggest excitement comes when members of the public report the balloons as UFOs.
If anyone had been living on Venus 25 years ago today, a weather balloon really would have been an alien spacecraft. A Soviet probe deployed a balloon more than 30 miles above the planet's surface.
Vega 1 was a complicated mission. It consisted of a balloon; a lander to measure conditions on the surface of Venus; and a carrier that would drop off the other two, then go on to fly past Halley's Comet.
They arrived at Venus on June 11th, 1985.
The lander worked for about an hour before the extreme surface temperature and pressure snuffed it out.
The balloon inflated just as planned, and began drifting along in the middle layer of Venus's clouds. Winds of up to 150 miles an hour pushed it eastward about 6,000 miles -- more than a quarter of the way around the planet.
The balloon worked for two days before its batteries failed. By then, a second balloon -- part of the Vega 2 mission -- was ready to take over the job of measuring the weather on a distant world.
And you can see that distant world tonight. Venus -- the "evening star" -- is in the west at nightfall. It forms the left end of a lineup of three bright points of light. The other two are Pollux and Castor, the "twin" stars of Gemini.
Script by Damond Benningfield, Copyright 2010