Old Farmer’s Almanac
Summer days are here. Summer begins with the solstice Thursday marking the astronomical first day of summer in the Northern Hemisphere.
What exactly is the summer solstice? Is it really the longest day of the year? Welcome the solstice with some interesting facts and folklore.
The June Solstice
In the Northern Hemisphere, the June solstice (aka summer solstice) occurs when the Sun travels along its northernmost path in the sky. This marks the astronomical start of summer in the northern half of the globe.
When is the Summer Solstice?
The June solstice occurs on Thursday at 3:51 p.m. CDT.
After the solstice, the sun appears to reverse course and head back in the opposite direction. The motion referred to here is the apparent path of the sun when one views its position in the sky at the same time each day, for example, at local noon.
Over the year, its path forms a sort of flattened figure eight, called an analemma. Of course, the sun itself is not moving (unless you consider its orbit around the Milky Way Galaxy); instead, this change in position in the sky that we on Earth notice is caused by the tilt of Earth’s axis as it orbits the sun, as well as Earth’s elliptical, rather than circular, orbit.
Does the Solstice Always Occur on the Same Day?
The timing of the June solstice is not based on a specific calendar date or time; it all depends on when the sun reaches its northernmost point from the celestial equator. Therefore, the solstice won’t always occur on the same day. Currently, it shifts between June 20, 21, and 22.
The Year’s Longest Day
The Summer Solstice is the day with the longest period of sunlight. Notice how the Sun appears highest in the sky at the solstice; its rays strike Earth at a more direct angle, causing the efficient warming we call summer.
Frequently Asked Questions
Q: Is the Summer Solstice the first day of summer?
A: Yes and no… Technically, it depends on whether we’re speaking about the meteorological or astronomical start of the season.
Most meteorologists divide the year into four seasons based on the months and the temperature cycle, which allows them to compare and organize climate data more easily.
In this system, summer begins June 1 and ends Aug. 31. Therefore, the summer solstice is not considered to be the first day of summer, meteorologically speaking.
Astronomically, however, the first day of summer is said to be when the sun reaches its highest point in the sky, which occurs on the summer solstice (June 20–22). Therefore, the summer solstice is considered to be the first day of summer, astronomically speaking.
Q: Is the Summer Solstice the longest day of the year?
A: Yes. As spring ends and summer begins, the daily periods of sunlight lengthen to their longest on the solstice, then begin to shorten again.
On the solstice, the sun is at its highest point in the sky, and it takes longer for it to rise and set. (Note: When the sun appears highest in the sky near the summer solstice, the full moon opposite the sun generally appears lowest in the sky.)
On the winter solstice, just the opposite occurs: The sun is at its lowest in the sky. At this time, the sun’s rays hit part of Earth at an oblique angle, creating feeble winter sunlight.
Q: Why doesn’t the summer solstice fall on the same date each year?
A: The summer solstice in the Northern Hemisphere ranges in date from June 20 to 22. This occurs in part because of the difference between the Gregorian calendar system, which normally has 365 days, and the tropical year (how long it takes Earth to orbit the Sun once), which has about 365.242199 days.
To compensate for the missing fraction of days, the Gregorian calendar adds a leap day about every four years, which makes the date for summer jump backward.
However, the date also changes because of other influences, such as the gravitational pull from the Moon and planets, as well as the slight wobble in Earth’s rotation.
Q: Why isn’t the Summer Solstice — the longest day of the year — also the hottest day of the year?
A: Earth’s atmosphere, land, and oceans absorb part of the incoming energy from the Sun and store it, releasing it back as heat at various rates. Water is slower to heat (or cool) than air or land.
At the summer solstice, the Northern Hemisphere receives the most energy (highest intensity) from the sun due to the angle of sunlight and day length.
However, the land and oceans are still relatively cool due to spring temperatures, so the maximum heating effect on air temperature is not felt just yet.
Eventually, the land and, especially, oceans will release stored heat from the summer solstice back into the atmosphere.
This usually results in the year’s hottest temperatures appearing in late July, August, or later, depending on latitude and other factors. This effect is called seasonal temperature lag.
Q: What is Midsummer Day (June 24)?
A: Historically, Midsummer Day marked the midpoint of the growing season, halfway between planting and harvest. It is traditionally known as one of four “quarter days” in some cultures — folks celebrate by feasting, dancing, singing, and preparing for the hot summer days ahead. Read more about the ancient Quarter Days.
Solstice Fun Facts
• The solstice does not bring the earliest sunrise
• Although the day of the solstice has the most daylight hours of the year, the earliest sunrises of the year occur before the summer solstice.
• The exact timing will depend in part on your latitude: In the mid-latitudes of the Northern Hemisphere, it occurs about a week earlier than the June solstice.
• The reason for the timing of sunrises is related to the inclination of the Earth’s rotational axis and Earth’s elliptical (rather than circular) orbit.
• The latest sunsets of the year will occur several days after the solstice, again depending on latitude.
• The sun sets more slowly at the solstice
• Did you know that the sun actually sets more slowly around the time of a solstice, in that it takes longer to set below the horizon? This is related to the angle of the setting sun.
• The farther the sun sets from due west along the horizon, the shallower the angle of the setting sun. (Conversely, it’s faster at or near the equinoxes.) Bottom line, enjoy those long, romantic summertime sunsets at or near the solstice.
