Sky Lights started out as a printed newspaper column, and it’s hard to justify the cost of color printing (unless you’re a widely syndicated cartoonist). So I started out with grayscale images, and just accepted the limitations that imposed. Later, when I made the transition to a local newspaper’s website, color became possible. Now, as an online blog, I use color whenever I can, as well as animations where needed. Some of the older posts will be re-released in color if the topic comes up again. But even now, especially for sky charts, sometimes grayscale is all I need.