Summer Solstice Saturday in 2020

Buttercups and Barn by Jamie MacDonald

Buttercups and Barn by Jamie MacDonald

Space.com reminds us that summer will officially arrive today (Saturday, June 20) with the summer solstice at 5:43:32 PM:

At the moment of the solstice, the sun will appear to be shining directly overhead for a point on the Tropic of Cancer (latitude 23.5 degrees north) in the central Pacific Ocean, 817 miles (1,314 kilometers) east-northeast from Honolulu. With the prime exception of Hawaii, we can never see the sun directly overhead from the other 49 U.S. states, but on Saturday, at around 1 p.m. local daylight time, the sun will attain its highest point in the sky for this entire year.

Since the sun will appear to describe such a high arc across the sky, the duration of daylight in the Northern Hemisphere is now at its most extreme, in most cases lasting over 15 hours. However, contrary to popular belief, the earliest sunrise and latest sunset do not coincide with the summer solstice. The earliest sunrise actually occurred back on June 14, while the latest sunset is not due until June 27. Dawn breaks early; dusk lingers late.

More from Space.com!

Jamie took this near Eaton Rapids three years ago on the summer solstice. See more shots of this great old barn in his The Barn album on Flickr.

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Today is not the Earth’s Longest Day

Untitled, photo by Jim Schoensee

The summer solstice arrives at 12:24 AM tomorrow when sun’s zenith is at its furthest point from the equator, making today the longest day of  2017. Vox’s article on the summer solstice has some interesting info about the solstice including a look at whether or not today is the longest day in Earth’s history:

Ever since the Earth has had liquid oceans and a moon, its rotation has been gradually slowing over time due to tidal friction. That means — over very, very long periods of time — the days have been getting steadily longer. About 4.5 billion years ago, it took the Earth just six hours to complete one rotation. About 350 million years ago, it took 23 hours. Today, of course, it takes about 24 hours. And the days will gradually get longer still.

Given that, you’d think 2017 would be the longest day in all of history. But while it’s certainly up there, it doesn’t quite take top honors.

That’s because tidal friction isn’t the only thing affecting Earth’s rotation — there are a few countervailing factors. The melting of glacial ice, which has been occurring since the end of the last ice age 12,000 years ago (and is now ramping up because of global warming), is actually speeding up Earth’s rotation very slightly, shortening the days by a few fractions of a millisecond. Likewise, geologic activity in the planet’s core, earthquakes, ocean currents, and seasonal wind changes can also speed up or slow down Earth’s rotation.

When you put all these factors together, scientists have estimated that the longest day in Earth’s history (so far) likely occurred back in 1912. That year’s summer solstice was the longest period of daylight the Northern Hemisphere has ever seen (and, conversely, the 1912 winter solstice was the longest night we’ve ever seen).

Eventually, the effects of tidal friction should overcome all those other factors, and Earth’s days will get longer and longer as its rotation keeps slowing (forcing timekeepers to add leap seconds to the calendar periodically). Which means that in the future, there will be plenty of summer solstices that set new records as the “longest day in Earth’s history.”

View Jim’s photo of the Charlevoix Lighthouse on the summer solstice in 2010 bigger and see more in his Charlevoix Lighthouse slideshow.

Summer Solstice and a Strawberry Moon

Summer Solstice 2013 by Ken Scott

Summer Solstice … 2013, photo by Ken Scott

Today at 6:34 PM EDT, the summer solstice officially ushers in summer. EarthSky shares that the full Strawberry moon tonight for the solstice is the first full moon to fall on the summer solstice since June of 1967 and the Summer of Love.

Back in 2001, NASA’s Earth Science Picture of the Day (<–my favorite photo blog – subscribe!) shared the tale of Eratosthenes, the Solstice and the Size of the Earth:

Calculating the SolsticeIt was near the summer solstice of 240 BC that Eratosthenes, curator of the famed Library of Alexandria and renowned mathematician and geographer, performed his famous experiment in Egypt to calculate the diameter of the Earth. The bottom of a deep well in the city of Syene, Egypt (near the present day Aswan Dam and very near the Tropic of Cancer) was known to be illuminated by the sun directly at mid-day on the longest day of the year (the solstice). But on the same day, a vertical pole in Alexandria, some 800 km to the north, cast a distinct shadow. By measuring the shadow and applying the geometry of a sphere, Eratosthenes calculated the Earth’s diameter with remarkable accuracy. Sadly, the concept of a spherical Earth was lost from common thought for over a thousand years until Christopher Columbus and others proved the fact by sailing west to go east. The background reference image of Egypt and the Nile River is provided by the NASA MODIS instrument.

Sep 5, 2006 – Donald Etz notes: “From reading Jeffrey Burton Russell’s book, Inventing the Flat Earth (1991), I was persuaded that most educated Europeans of Columbus’ time believed the earth is round. The main debate seems to have been over its dimensions. Columbus ventured on his voyage because he believed the earth was much smaller than it is.” -ed

View Ken’s photo of the sunrise on the 2013 summer solstice bigger, see more in his Boat(s) slideshow, and definitely check out kenscottphotography.com to view and purchase his work.

More science on Michigan in Pictures.

 

 

Chasing the Sun on the Summer Solstice

I chased the sun tonight

I chased the sun tonight, photo by Todd

If you were up at 4:51 AM this morning marking summer solstice, you have a long day ahead of you. The longest of the year in fact! More about the summer solstice at EarthSky and I hope you enjoy today and your summer!

View Todd’s photo bigger and see more in his Photo Paddling slideshow.

More about solstices on Michigan in Pictures.