Neptune's weather - planet may have increasing atmospheric outbursts - Brief Article

Science News, Oct 24, 1992

A new analysis of old data suggests that Neptune periodically develops an atmospheric burp - a localized outburst similar to Saturn's white spot (SN: 11/23/91, p.332).

In examining images of Neptune taken by the Voyager 2 spacecraft and measurements of the planet's luminosity recorded by an Earthbased telescope, MIT astronomer Heidi B. Hammel and G. Wesley Lockwood of Lowell Observatory in Flagstaff, Ariz., realized they were tracking a bright, expanding blob high in the planet's atmosphere. For example, they found that the typical daily variation in Neptune's visible-light intensity doubled in 1986. By 1987, the planet's infrared luminosity had increased five-fold. And in 1988, although the overall variation in Neptune's brightness declined, the side of the planet opposite the luminous blob increased in brightness, indicating that the atmospheric outburst had spread in a belt around the planet, a movement akin to that of Saturn's white spot.

Hammel notes that Neptune experienced a similar burp in the infrared in the mid-1970s, and she now plans to track the evolution of the next outburst. She reported the work last week at the astronomy meeting in Munich.