Summer arrives at 12:38 p.m. Sunday, the moment of solstice. But what does that mean?
The solstice is the point at which the North Pole is tilted furthest toward the sun, at an angle of 23.5 degrees. With that comes the year's most intense sunlight for the Northern Hemisphere.
Here's what else it means -- and doesn't mean:
- "Solstice" means sun-stopping, derived from the Latin word solstitium, according to timeanddate.com. That's because it's when the sun reaches its northernmost or southernmost point on the horizon, depending on whether one is in the Northern or Southern hemisphere, according to EarthSky.org. For us at the summer solstice, the sun will set Sunday at its northernmost point from due west, and it will start setting south of that point each night until the winter solstice.
- Our summer solstice is the "longest day" of the year -- the one with the most daylight hours -- in the Northern Hemisphere. It's meanwhile the longest night of the year in the Southern Hemisphere. In Baltimore, we will get 14 hours, 56 minutes of daylight on the solstice, and for a few days before and after it.
- The solstice doesn't coincide with the earliest sunsets or latest sunrises. Those come about a week before and after the solstice, respectively. The year's earliest sunsets in Baltimore, at 5:39 a.m., already came, and the latest sunsets, at 8:37 p.m., come at the end of this month. That's because the "solar" clock and our clock do not precisely align -- solar noon, when the sun reaches its highest point in the sky each day, does not occur at noon on our clock. Our clock is based on "mean solar time".
- The solstice isn't the hottest day of the year, despite the fact that it's the day we get the most intense sunshine. That's because of a lagging effect in land and water's absorption of the sun's energy, according to The Old Farmer's Almanac.
- The solstice falls on different days, depending on quirks in the calendar and other factors. This year it's June 21, but next year, it's June 20. In 2203, it will be June 22, according to timeanddate.com. It can vary because of leap years, but also because the influence of other planets and the “wobble” in the Earth's axis, according to the site.