Sunday marked the the first official day of summer in the Southern Hemisphere, where Skipper Wilson and his fellow sailors are making their way east. Solstices occur twice each year — once in June and once in December. In the Northern Hemisphere, the winter solstice was celebrated with snow falling across the United States and Canada. For those of us north of the equator, we’re now officially in winter. For those people, like Skipper Wilson, who are south of the equator, they’ve moved into the summer months.

Two things cause seasons. The first is that the Earth revolves around the sun. The second is that the Earth is tilted on its axis. (Imagine a ball with a stick pushed through its middle. If the Earth is the ball and the stick represents the North and South Poles, then the stick isn’t straight up and down, but leans over at an angle.)

The solstice marks the extremes of light that the Earth receives. On December 21, the Northern Hemisphere was tilted the furthest from the sun that it gets all year. That means that you didn’t get a lot of daylight and instead had a very long night. The Southern Hemisphere, however, was tilted closest to the sun so it had many hours of daylight.

When you’re sailing, it’s good to have lots of hours of daylight because it’s easier to be able to see what’s going on around you. You can read here what Skipper Wilson has been up to since the longest day of the year in the Southern Hemisphere.