This video courtesy of NASA shows the equinoxes and solstices from space.
Monday may feel like the longest day of the week, but this Monday will actually be the longest day of the year.
That is, it will have the most daylight of the year.
Monday, June 20, is the summer solstice, the day on the calendar with the most daylight for those in the Northern Hemisphere.
Here a few things to know as we begin what many consider the first day of summer.
1. Today has the most daylight of any day this year north of the equator
The Sun is directly overhead at "high-noon" on the summer solstice at the latitude called the Tropic of Cancer. (NASA)
Everywhere north of the equator will have at least 12 hours of daylight today.
Birmingham, for example, will have 14 hours, 22 minutes and 42 seconds of daylight on Monday. Miami will have 13 hours and 45 minutes of daylight, San Francisco 14 hours, 46 minutes and 54 seconds and New York City will have 15 hours, five minutes and 37 seconds.
Alaska takes the prize, though.
2. There are 24 hours of daylight above the Arctic Circle
It's called the midnight sun. The boundary of the midnight sun is the Arctic Circle. That marks the lowest latitude at which the sun remains above the horizon for a full 24 hours during summer solstice and below the horizon for a full 24 hours during winter solstice in December.
Nearly one-third of Alaska lies above the Arctic Circle, according to the Alaska Public Lands Information Center.
3. The full moon and June solstice will both happen June 20 for the first time in decades
Once in a lifetime event tomorrow. 1st time since 1948 where 1st day of summer occurs with a full "strawberry" moon. pic.twitter.com/icIXNhSD8C
— NWS Kansas City (@NWSKansasCity) June 19, 2016
The last time the June full moon, sometimes called the "strawberry moon," and the summer solstice fell on the same day was 1948.
According to EarthSky.org, the two won't share the same calendar square again until June 21, 2062.
4. After today, the days begin to get shorter
Monday's summer solstice and full moon
This composite from 2010 and 2011 shows sunlight hitting the earth during the winter solstice (upper left), spring equinox (upper right), summer solstice (lower left) and fall equinox (lower right). Photo courtesy of NASA.Grant Segall, The Plain Dealer
The days begin to shrink by seconds each day from Tuesday until the winter solstice, which this year falls on Dec. 21 at 4:44 a.m. CST. On that day there will be only 10 hours and nine minutes and 37 seconds of daylight in Mobile. The farther north you go, the shorter the day length. Birmingham will have nine hours and 55 minutes and 46 seconds of daylight on Dec. 21; Huntsville gets only nine hours, 49 minutes and 31 seconds.
5. The earliest sunrises don't always fall on the solstice
The summer solstice has one of the earliest sunrises of the year (but not necessarily the earliest). For example, Birmingham, Ala., saw its earliest sunrises on June 4-19, at 5:37 a.m. CDT. Birmingham's sunrise on Monday will be at 5:38 a.m. (Huntsville's earliest sunrises were at 5:33 a.m. on June 4 through today. Mobile's earliest sunrises were at 5:49 a.m. CDT June 3-18. Monday's sunrise will be at 5:50 a.m.)
6. The summer solstice falls only on one of three days
The summer solstice usually occurs on June 20 or 21, and rarely on June 22. According to TimeandDate.com, the next solstice on June 22 won't be until 2203. The last one was in 1975.
7. The solstice happens worldwide at the same time
The summer solstice occurs this afternoon. pic.twitter.com/P74Wp9i4M5
— NWS Shreveport (@NWSShreveport) June 20, 2016
The summer solstice occurs when the sun is directly over the Tropic of Cancer, located at latitude 23.5 degrees North. (It runs through Mexico, the Bahamas, Egypt, Saudi Arabia, India and southern China.) The sun will be directly over the Tropic of Cancer at 5:34 p.m. CDT on Monday.
The summer solstice in the Northern Hemisphere occurs at the same moment the winter solstice occurs in the Southern Hemisphere.
8. It's the longest day of the year, but not usually the hottest
warmest day of the year.jpg
When should you expect the hottest weather of the summer? In Alabama it ranges from mid-July through mid-August, according to NOAA. (NOAA map)
According to the National Weather Service, there is about a six-week lag between the longest day of the year and the warmest average temperatures for most mid- and high-latitude locations.
Through the next couple months, the atmosphere and oceans in the Northern Hemisphere will continue to absorb -- and slowly release -- energy from the sun.
Even though more energy absorption is taking place on the summer solstice, it'll take about another six weeks for us to feel the highest temperatures.
Facts about the June 20 'strawberry moon'