DO PLANETS KNOW ABOUT SHRINKAGE? Great Red Spot Not Doing So Great: A long-term shrinking appears to be accelerating. “Observations made from Earth in the 1800s suggest that the Red Spot was once over 40,000 km across. By the time the Voyagers visited and provided an accurate measure, the Spot was down to 23,000 km. Hubble has been taking images regularly, but NASA credits amateur astronomers for noticing that the rate of the storm’s dissipation picked up in 2012, with the feature losing 900 km of diameter (559 miles) a year since then.” Amateur astronomers notice a lot.