Recently, commenting on images seems to mean complaining about captions. How sad. But here I go again…
The image above accompanies a press release on a three percent reduction in upper-atmosphere density by the year 2017. The caption for the image reads simply, “The outermost layer of the atmosphere will lose three percent of its density over the coming decade.” Which is all well and good (I mean, the caption is all well and good), except that it leaves one wondering what the satellite is doing in the image. Perhaps the caption could be expanded slightly to read, “The outermost layer of the atmosphere, which extends as high as some satellite orbits, will lose three percent of its density over the coming decade.” Just as a first pass.
A little later in the press release, we find out that “lower density in the thermosphere, which is the highest layer of the atmosphere, would reduce the drag on satellites in low Earth orbit, allowing them to stay airborne longer.” Well, golly, that makes an even better caption: “The outermost layer of the atmosphere will lose three percent of its density over the coming decade, allowing satellites to stay aloft longer.” (Somehow, “airborne” seems inappropriate when applied to a satellite.)
And while I’m discussing language instead of images, what’s up with the headline for this press release? “Scientists Predict Carbon Dioxide Emissions Will Reduce Density of Earth’s Outermost Atmosphere by 2017.” Um, well, actually, emissions have already reduced the density, and they will most likely continue to reduce the denisty long after 2017. Somewhat deceptive.