Today’s summer solstice in the northern hemisphere does not bring only the longest day of the year. Night sky watchers also have the opportunity to see, for the first time in 49 years, a full moon on the first day of summer.
The full moon occurs about once each month. The lunar year – the amount of time it takes for the moon to cycle through 12 lunar cycles – is 354 days; the lunar cycle averages 29.53 days.
A full moon occurs when the sun, Earth, and the moon are nearly aligned. During most full moons we see nearly all of one of the Moon’s hemispheres from our planet. We do not see all of that hemisphere during a typical full moon because, if we did, the sun, Earth, and moon would be so aligned as to result in a lunar eclipse.
The other hemisphere of the moon is never visible from Earth because the moon’s rate of rotation is equal to the amount of time it takes to orbit our planet.
Because tonight’s full moon occurs in June, it is colloquially known as a “strawberry moon.” According to the 1918 book The American Boy’s Book of Signs, Signals and Symbols, the nickname originated with native Americans of the northeastern United States because June is the month in which strawberries were harvested.
According to a 2012 National Geographic article, “Europeans have dubbed [a June full moon] the rose moon, while other cultures named it the hot moon for the beginning of the summer heat.”
The summer solstice in the northern hemisphere is the one day of the year on which the sun will be directly overhead at noon at the Tropic of Cancer. The sun is never directly overhead at a latitude north of the Tropic of Cancer or south of the Tropic of Capricorn.
In Colorado and the rest of the Mountain Time Zone of North America, the sun will get to its annual highest point in the sky at 4:34 pm.
The sun is directly overhead at high noon above the Tropic of Capricorn on the winter solstice in the northern hemisphere.
The southern hemisphere experiences its summer solstice on that day and its winter solstice when the sun is directly overhead at the Tropic of Cancer.
CORRECTION, June 20, 2016, 5:24 pm MDT: This article originally stated that the last summer solstice full moon occurred in 1949, 67 years ago. That is not an accurate statement and the article has been edited to correct the error.
Summer has begun here in North America. Hooray!
I know, you are saying to yourself “What’s up with this guy, I’ve been out of school for weeks!” But, my friend, I’m not talking about the first day you got to sleep in. No, I’m talking about the solstice.
Earth’s two solstices occur because the planet is tilted on its axis. In the northern hemisphere, the 23.4 degree tilt from the ecliptic means that the north pole is closer to the sun than it is at any other time of the year.
The result is that the sun’s path across the sky in the northern hemisphere is longer than it will be on any other day of the year.
Down south, of course, it’s a different story. Today is the winter solstice there because the south pole is tilted as far away from the sun as it will be all year.
So, yes, go ahead and feel good about sleeping in this morning. You’ve got a long, long day in which to get outside and shake off all that lethargy. The sun won’t set in mid-latitude areas of North America until after 9:00 pm, and if you are living in the Great White North the sun will not set until quite a bit later than that.