A double delight awaits on July 27, with a full moon and the planet Mars in opposition—a fiery dot visible in the southeast about 15 minutes after the 8:27 p.m. sunset.

In the warmer waters of Tomales Bay, moon jellies are washing up on beaches. The clear bodies have a pattern of four white half moons in the center. As surface dwellers, they are more susceptible to temperature changes, and seasonal die-offs occur after spells…