The weather is heating up in Milwaukee this week, but it’s not yet the official start of summer. Tomorrow, June 20, is the summer solstice — which is both the longest day and shortest night in the Northern Hemisphere.
So what’s the difference between astronomical summer and meteorological summer, and what makes the solstice special around the world?
Jean Creighton is WUWM’s regular astronomy contributor and the director of UW-Milwaukee's Manfred Olson Planetarium. She joins Lake Effect’s Audrey Nowakowski to explain, beginning with what causes this astronomical event known as the summer solstice.
"The sun moves along our horizon, and that's principally because the Earth is tilted ... what we see is that the height of the sun changes," she says. "And its location of sunrise and sunset also shifts over the course of the year."
The solstice marks the day when the sun "stands still" and then changes direction, Creighton says.
"The sun pauses its northward motion, and then it starts moving south," she says.
From Stonehenge in the U.K. to Egypt's Nabta Playa monument and more, many cultures throughout history have celebrated the solstice and used it as a guide for agriculture.
"I think the fact that we have so directly connected the celestial with daily activities [in the past] is just a fascinating aspect that I wish we did more of," Creighton says.
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