About “Exoplanets for Whom” (from Prof. Courtney Dressing)

 Here’s a note to 10Q Co-Host Alyssa Goodman from Prof. Courtney Dressing, author of the work presenting the image above. [Bracketed information] added for clarification.
“It’s fun to see the press release image side-by-side with Figure 17b [the image from the article, at right, above]. Although I initially made the version on the left for a press conference, I always show that version instead of the version on the right. The host star temperature information is intriguing, but the left version of the figure is so much cleaner and clearer that I use it instead of Figure 17b even when speaking to exoplanet experts. The biggest changes I made in converting the published figure into the press image were removing the error bars and eliminating the host star temperature information (and the terrible color scale). I tried to follow the advice of David Aguilar and Christine Pulliam [public affairs experts] by figuring out exactly what I wanted readers to learn from the figure and removing everything that didn’t specifically address those points.
The take-away points I chose were:
  1. There are lots of planets orbiting red dwarfs.
  2. Three of those planets might be habitable!
Once I identified those key points, I decided to remove the error bars and color scaling so that it was easier for the reader to see how many planets appeared in the image and how many of them fell within the habitable zone. (In hindsight, it might have been helpful to label the green band using either words or a cartoon image depicting habitability.)
Next, I knew that I wanted to emphasize the planets within the habitable zone, so I made those dots bigger and tried to pick a color that stood out more than the gray I used for the other planets.
Finally, I wanted to translate the figure from somewhat abstract numbers into relatable units. I tried to do this by changing the axis labels from “Planet Radius” and the jargony phrase “Flux Received by Planet” into “Size of Planet Relative to Earth” and “Light Received by Planet Relative to Earth.”
Many images of the solar system show the Sun at the left and the planets on the right (maybe because English-speakers read left to right?), so I wanted it to be very clear to the reader that the more highly irradiated planets were on the right side of the figure. I did this by adding the “Towards Star —>” text at the top right. Next, I wanted to translate the plot into a more relatable insolation scale so I added on the solar system planets at the top of the plot. I could have placed these planets within the plot area itself at the proper combinations of size and light received, but I chose to place them above because I didn’t want the Earth to obscure any of the data points. I’d be curious to learn whether that decision to place the planets at the top rather than within the grid makes the figure more or less clear. [AG thinks less clear, sorry!]”