157381355

157381355

Sunrse through the ancient standing stones of Callanish 1

Photo by: JayKay57

JayKay57

The Summer Solstice is Upon Us

Dr. Jeff Hall at Lowell Observatory in Flagstaff, Arizona clues us in on some awesome facts about Summer Solstice.

June 18, 2020

June 20, 2020 marks the first day of summer and the longest day of the year. Dr. Jeff Hall, astronomer and Director at Lowell Observatory in Arizona makes some things clear about the importance of the event celebrated throughout the millennia.

What is the astronomical significance of the June Solstice?

It’s one of the key points in the apparent path of the Sun through the sky over the course of the year. At the June solstice, the Sun reaches its most northerly declination, which you can think of as its celestial latitude. Its declination on this day will be about 23.5 degrees north, matching the 23.5-degree tilt of Earth’s rotational axis. On the June solstice, the Sun will traverse higher in the sky in the northern hemisphere than on any other day (and, conversely, it will be at its lowest in the sky in the southern hemisphere). The June solstice marks the beginning of northern hemisphere summer and the beginning of southern hemisphere winter.

700171156

700171156

HOBOKEN, NJ - JUNE 21: The sun rises behind the skyline of midtown Manhattan and the Empire State Building on the summer solstice in New York City on June 21, 2017 as seen from Hoboken, NJ.

Photo by: Gary Hershorn

Gary Hershorn

HOBOKEN, NJ - JUNE 21: The sun rises behind the skyline of midtown Manhattan and the Empire State Building on the summer solstice in New York City on June 21, 2017 as seen from Hoboken, NJ.

Will we notice anything differently on earth?

There will be nothing particularly dramatic – at least, not anything that’s due to the Sun. The Sun will be only imperceptibly higher in the sky in the northern hemisphere than it is a week before or a week after the solstice.

The highest point the Sun reaches in the sky does depend on your latitude. The declination directly overhead (i.e., at your local zenith) equals your latitude. So for example, in Miami (latitude 24.7 north) the Sun will pass almost directly overhead – only about 1.2 degrees from the zenith or, equivalently, 87.8 degrees up from the horizon. But in Seattle (latitude 47.6 north), the Sun will be just over 24 degrees from zenith, or about 66 degrees from the horizon.

That actually makes a big difference and is one of a number of reasons for changes in climate from season to season and at different latitudes. For example, consider the dates when the Sun is directly above the equator (at the spring and fall equinoxes). For someone living in Quito, Ecuador, pretty much right on the equator, the Sun will pass directly overhead. But for someone in Helsinki, at about 60 degrees north, the Sun will only be 30 degrees above the horizon. In that circumstance, the intensity of solar radiation in Helsinki is only half what it is in Quito! This is the principal reason that summer in either hemisphere is much warmer than winter: it’s the intensity of the radiation from the Sun’s much more direct pass more nearly overhead than from its oblique pass during the winter.

Live from Lowell

Join Lowell on Saturday at 5:30 PM ET/2:30 PM PT to watch a discussion about the significance of this annual occurence.

Next Up

The End of the World is NOT Sunday

The Mayan calendar predicted the end of the world in 2012, but we’re still here. Others are claiming that the Mayan calendar actually predicted the end of the world for June 21, 2020, so we shall see? Probably not.

Earth Day: The Perspective from Space

Greetings Earthlings! Astronomers from Lowell Observatory discuss the iconic Pale Blue Dot shot of the Earth and other Earth-like planets.

Everybody is Equal in the Equinox

Here comes the sun! At least, if you live in the northern hemisphere of the Earth.

Earth Observation: Tackling the Climate Crisis through Data

Earth observation data is one of the best ways to study and reverse climate change.

Geothermal Power: Heat and Light from Below the Earth

Is geothermal power the best chance to lasting and sustainable power for generations?

The First All-Female Spacewalk in NASA’s 61-Year History is Happening

"A-team" astronauts Christina Koch and Jessica Meir are set to make history in the first all-female spacewalk.

The Last Supermoon of the Year and How to See It

The Super Flower Moon of May is this year's last supermoon, when the Moon appears slightly larger and brighter in the sky because it is somewhat closer to Earth. Here's everything you need to know and how to watch it from home.

The COVID-19 Vaccine Race

The development of a vaccine for COVID-19 has been a global all hands on deck initiative since the Coronavirus pandemic took hold of the world in early 2020. Recently two pharmaceutical giants-Pfizer and Moderna- have announced successful ongoing trials. Updated: November 18, 2020

US Navy Released UFO Video Footage to Little Fanfare Amidst Pandemic

The previously leaked videos have been declassified and confirmed to be real by the Pentagon. Science Channel's BLACK FILES DECLASSIFIED host Mike Baker talks us through these "unidentified objects" that were sighted.

Oil Spill Clean Up: Boom or Bust for Slicks at Sea

Oil spills at sea are an environmental nightmare. The mix of churning seawater and crude oil make containing and mopping up one of Earth's most polluting substances extremely hazardous.