While we often talk about the “Ozone Hole” over the Antarctic, we rarely talk about what ozone levels are like above our own heads. While the thinning of the ozone layer over the South Pole points to potential problems that we might experience here one day, it would be nice to know what our current situation is. In this week’s activity, we will do just this with the aid of data from 4 different satellites that have been monitoring ozone levels around the world for the last several decades. The Total Ozone Mapping Spectrometer (TOMS) Program was started in 1978 to provide scientists with a global view of the stratospheric ozone layer. Until this time, the only measurements that had been taken of it were from ground-based instruments that were limited to the thickness of the layer directly above the instrument. With the placement of the TOMS instrument on the Nimbus-7 satellite, we began period of being able to “see” the entirety of the layer in real time. Since that first instrument, there have been three additional instruments placed on orbiting satellites: the Russian Meteor-3, the Japanese Advanced Earth Observing Satellite (ADEOS), and the NASA Earth Probe satellite. With the exception of an 18-month gap in 1994-1995, we have a continuous data set for ozone measurements.