June Solstice - Summer and Winter Solstice Equinoxes and solstices from 2000–2049 Zenith Furthest Away from the Equator A solstice happens when the sun's zenith is at its furthest point from the equator. On the June solstice, it reaches its northernmost point and the Earth’s North Pole tilts directly towards the sun, at about 23.4 degrees . It's also known as the northern solstice because it occurs when the sun is directly over the Tropic of Cancer in the Northern Hemisphere. 11 Facts About the June Solstice Meaning of Solstice 'Solstice' (Latin: 'solstitium') means 'sun-stopping'. The point on the horizon where the sun appears to rise and set, stops and reverses direction after this day. On the solstice, the sun does not rise precisely in the east, but rises to the north of east and sets to the north of west, meaning it's visible in the sky for a longer period of time. Although the June solstice marks the first day of astronomical summer, it's more common to use meteorological definitions of seasons, making the solstice midsummer or midwinter. Stonehenge in England.

Solstices in Culture Over the centuries, the June solstice has inspired countless festivals, midsummer celebrations and religious holidays. One of the world's oldest evidence of the Summer Solstice's importance in culture is Stonehenge in England, a megalithic structure which clearly marks the moment of the June Solstice. In the Southern Hemisphere, where the June solstice is known as the shortest day of the year, it marks the first day of astronomical winter, but the middle of winter in meteorological terms. Midnight Sun or Polar Night? On the June solstice, the midnight sun is visible ( weather permitting ) throughout the night, in all areas from just south of the Arctic Circle to the North Pole. On the other side of the planet, south of the Antarctic Circle there's Polar Night, meaning no Sunlight at all, on the June Solstice. Solstice Dates Vary Even though most people consider June 21 as the date of the June Solstice, it can happen anytime between June 20 and June 22, depending on which time zone you're in.

June 22 Solstices are rare - the last June 22 Solstice in UTC time took place in 1975 and there won't be another one until 2203. The varying dates of the solstice are mainly due to the calendar system – most western countries use the Gregorian calendar which has 365 days in a normal year and 366 days in a Leap Year . A tropical year is the time it takes the Earth to orbit once around the Sun. It is around 365.242199 days long, but varies slightly from year to year because of the influence of other planets. The exact orbital and daily rotational motion of the Earth, such as the “wobble” in the Earth's axis (precession of the equinoxes), also contributes to the changing solstice dates. Moving to Other Seasons Equinoxes and Solstices Equinoxes and Solstices happen twice a year, but not always on the same date.

After the June solstice, the sun follows a lower and lower path through the sky each day in the Northern Hemisphere until it reaches the point where the length of daylight is about 12 hours and eight to nine minutes in areas that are about 30 degrees north or south of the equator. Areas 60 degrees north or south of the equator have daylight for about 12 hours and 16 minutes. This is the September Equinox , the Autumnal Equinox in the Northern Hemisphere. Earth does not move at a constant speed in its elliptical orbit. Therefore the seasons are not of equal length: the times taken for the sun to move from the March Equinox to the June Solstice , to the September equinox, to the December solstice , and back to the March equinox are roughly 92.8, 93.6, 89.8 and 89.0 days respectively. The consolation in the Northern Hemisphere is that spring and summer last longer than autumn and winter. o In the southern hemisphere the winter solstice occurs on - SCIENCE - 214 View Full Document o In the southern hemisphere the winter solstice occurs on or near June 21.

Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. At what time of day is sunlight strongest – in the early morning (when the Sun has just risen) or at noon (when the Sun reaches its highest point)? At noon 2. At what time of year does the noon Sun rise highest in the sky? Early summer 3. Based on your answers, why is it warmer in summer than in winter? The earth is facing the sun more Gizmo Warm-up The reasons for seasons have a lot to do with the angle at which the Sun’s rays hit Earth. To see why, select the PLATE tab on the Seasons: Why do we have them? Gizmo™. The image shows a solar panel ( Plate M ) facing the Sun. Check that the Axis angle is set to 0˚. 1. Click Fire to release 100 “rays” of sunlight. Look next to “Number of hits” below the plate. How many of these rays hit Plate M ? 100 hits 2. Click Reset . Change the Axis angle to 40˚, and click Fire . How many rays hit Plate M now? 76 hits 3.

Which do you think will warm up the plate more quickly? (Circle one.) A. Direct sunlight (sunlight that hits the plate at a 90° angle) B. Indirect sunlight (sunlight that hits the plate at an angle of less than 90°) This preview has intentionally blurred sections. Sign up to view the full version. View Full Document Activity A: Sunlight on a plate Get the Gizmo ready :  Click Reset . Question: How does the angle of sunlight affect the amount of energy that is absorbed? 1. Form hypothesis : How do you think the angle of the plate will affect how much sunlight hits the plate? It determines how much sunlight will hit the earth 2. Collect data : Set the Axis angle to -80° and click Fire . Record the Number of hits . Repeat for each angle and fill in the tables below. You can use the slider or type the number into the text field directly and click Enter on your keyboard.

(Note that “0°” appears in both tables.) Axis angle Hits -80° 18 -60° 50 -40° 76 -20° 92 0° 100 Axis angle Hits 0° 100 20° 92 40° 76 60° 50 80° 18 3. Analyze : What is the relationship between the axis angle and the number of solar rays that hit the plate? The greater the angle, the fewer the number of solar rays that hit the plate. This is the end of the preview. Sign up to access the rest of the document.

TERM 9.8 Gizmo Coastal Winds and Clouds.doc Northwest Guilford High Name: _ Date: _ Student Exploration: Coastal Winds and Clouds Vocabulary: Condensatio 9.8 Gizmo Coastal Winds and Clouds.doc The Seasons, the Equinox, and the Solstices The Seasons, the Equinox, and the Solstices Weather.gov > Cleveland, OH > The Seasons, the Equinox, and the Solstices Submit a Storm Report The Equinox (Vernal & Autumnal) There are only two times of the year when the Earth's axis is tilted neither toward nor away from the sun, resulting in a "nearly" equal amount of daylight and darkness at all latitudes. These events are referred to as Equinoxes.The word equinox is derived from two Latin words - aequus (equal) and nox (night). At the equator, the sun is directly overhead at noon on these two equinoxes. The "nearly" equal hours of day and night is due to refraction of sunlight or a bending of the light's rays that causes the sun to appear above the horizon when the actual position of the sun is below the horizon.

Additionally, the days become a little longer at the higher latitudes (those at a distance from the equator) because it takes the sun longer to rise and set. Therefore, on the equinox and for several days before and after the equinox, the length of day will range from about 12 hours and six and one-half minutes at the equator, to 12 hours and 8 minutes at 30 degrees latitude, to 12 hours and 16 minutes at 60 degrees latitude. The Solstices (Summer & Winter) The summer solstice occurs at the moment the earth's tilt toward from the sun is at a maximum. Therefore, on the day of the summer solstice, the sun appears at its highest elevation with a noontime position that changes very little for several days before and after the summer solstice. The summer solstice occurs when the sun is directly over the Tropic of Cancer, which is located at 23.5° latitude North, and runs through Mexico, the Bahamas, Egypt, Saudi Arabia, India, and southern China. For every place north of the Tropic of Cancer, the sun is at its highest point in the sky and this is the longest day of the year.

The winter solstice marks the shortest day and longest night of the year. In the Northern Hemisphere, it occurs when the sun is directly over the Tropic of Capricorn, which is located at 23.5° south of the equator and runs through Australia, Chile, southern Brazil, and northern South Africa. For a complete listing of the dates of the winter and summer solstice's and spring and fall equinox's through 2025, check out this site from the U.S. Naval Observatory. The Seasons We all know that the Earth makes a complete revolution around the sun once every 365 days, following an orbit that is elliptical in shape. This means that the distance between the Earth and Sun, which is 93 million miles on average, varies throughout the year. During the first week in January, the Earth is about 1.6 million miles closer to the sun. This is referred to as the perihelion. The aphelion, or the point at which the Earth is about 1.6 million miles farther away from the sun, occurs during the first week in July.

This fact may sound counter to what we know about seasons in the Northern Hemisphere, but actually the difference is not significant in terms of climate and is NOT the reason why we have seasons. Seasons are caused by the fact that the Earth is tilted on its axis by 23.5°. The tilt's orientation with respect to space does not change during the year; thus, the Northern Hemisphere is tilted toward the sun in June and away from the sun in December, as illustrated in the graphic below. The Relationship Between Length of Day and Temperature There is a lag between the longest day of the year and the warmest average temperatures for most mid and high latitude locations. In northern OH/northwest PA, the maximum daily temperature occurs nearly 3 weeks later in mid July. Just as the warmest part of the day usually occurs several hours after noon, when the sun is highest in the sky, so too does the warmest part of the summer lags the summer solstice. This lag is due to the time required for ground and water to heat up. Average temperatures continue to climb until the sun drops lower in the sky. While the effect is evident in a daily temperature plot, it is more readily apparent by looking at changes in the monthly average temperature.

In Cleveland, July averages 3.3°F degrees higher than June, with August also warmer than June by 2.8°F, even though the length of days in August is considerably less than the length of days in June. December Solstice Equinoxes and solstices from 2000–2049 The Sun's Position The Sun is directly overhead of the Tropic of Capricorn in the Southern Hemisphere during the December Solstice. The December Solstice occurs when the Sun reaches its most southerly declination of -23.4 degrees . In other words, when the North Pole is tilted furthest away from the Sun. Midnight Sun or Polar Night Being the longest day of the year, also means that people in the areas south of the Antarctic Circle towards the South Pole will see the Midnight Sun , i.e. have 24 hours of daylight, during this time of the year. Sunrise & Sunrise Worldwide For people in the Northern Hemisphere, the December solstice marks the exact opposite, the day of the year with fewest hours of daylight. North of the Arctic Circle towards the North Pole there is no direct sunlight at all during this time of the year.

Solstices in Culture The December solstice has played an important role in cultures worldwide from ancient times until our day. Even Christmas celebrations are closely linked to the observance of the December solstice. There are also customs linked to the June solstice along with traditions linked to the Spring (vernal) equniox and the Fall (autumnal) equinox . December solstice in the Calendar December 21 or 22 solstices happen more often than December 20 and 23 solstices. The last December 23 solstice was in 1903 and will not happen again until 2303. A December 20 solstice has occurred very rarely, with the next one in the year 2080. (*) Why Do the Dates Vary? As with the June solstice, the December solstice’s varying dates are mainly due to the calendar system. The Gregorian calendar , which is used in most western countries, has 365 days in a common year and 366 days in a leap year .

However, the tropical year, which is the length of time the sun takes to return to the same position in the seasons cycle (as seen from Earth), is different to the calendar year. The tropical year is approximately 365.242199 days but varies from year to year because of the influence of other planets. The exact orbital and daily rotational motion of the Earth, such as the “wobble” in the Earth's axis (precession), also contributes to the changing solstice dates. The solstices can also be observed by noting the point of time when the sun rises or sets as far south as it does during the course of the year (winter in the Northern Hemisphere) or maximally north (summer in the Northern Hemisphere). Is the Year's Earliest Sunset on the Winter Solstice? December solstice and seasons It is important to note that Earth does not move at a constant speed in its elliptical orbit.

Therefore the seasons are not of equal length: the times taken for the sun to move from the vernal equinox to the summer solstice, to the autumnal equinox, to the winter solstice, and back to the vernal equinox are roughly 92.8, 93.6, 89.8 and 89.0 days respectively. The consolation in the Northern Hemisphere is that spring and summer last longer than autumn and winter (when the December solstice occurs). The relative position of the Earth's axis to the sun changes during the cycle of seasons. This phenomenon is the reason why the sun’s height above the horizon changes throughout the year. It is also responsible for the seasons through controlling the intensity and duration of sunlight received at various locations around the planet. End of the world in Mayan calendar In 2012, the December Solstice coincided with the end of the “Great Cycle” of the Long Count in the Mayan calendar . Many saw this as a prophecy of the end of the world . (*) All dates refer to Coordinated Universal Time (UTC) . Dates may vary depending on the time zone.

Winter Solstice - Geography Winter Solstice December 21-22 Solstice is Winter in Northern Hemisphere RK Studio/Dean Sanderson/Getty Images By Matt Rosenberg Updated November 30, 2016. The time around December 21 or 22 is a very important day for our planet and its relationship with the sun. December 21 is one of two solstices, days when the rays of the sun directly strike one of the two tropical latitude lines . In 2014 at precisely 6:03 p.m. EST (23:03 UTC ) on December 21, 2014 winter begins in the Northern Hemisphere and summer begins in the Southern Hemisphere . The earth spins around its axis, an imaginary line going right through the planet between the north and south poles. The axis is tilted somewhat off the plane of the earth's revolution around the sun. The tilt of the axis is 23.5 degrees; thanks to this tilt, we enjoy the four seasons. For several months of the year, one-half of the earth receives more direct rays of the sun than the other half. The earth's axis always points to the same point in the universe.

When the axis points away from the sun from December to March (because of the relative location of the earth to the sun), the southern hemisphere enjoys the direct rays of the sun during their summer months. continue reading below our video Overview of the Four Seasons Alternatively, when the axis tilts towards the sun, as it does between June and September , it is summer in the northern hemisphere but winter in the southern hemisphere. December 21 is called the winter solstice in the Northern Hemisphere and simultaneously the summer solstice in the Southern Hemisphere. On June 21 the solstices are reversed and summer begins in the northern hemisphere . On December 21, there are 24 hours of daylight south of the Antarctic Circle (66.5° south of the equator) and 24 hours of darkness north of the Arctic Circle (66.5° north of the equator). The sun's rays are directly overhead along the Tropic of Capricorn (the latitude line at 23.5° south, passing through Brazil, South Africa, and Australia) on December 21. Without the tilt of the earth's axis, we would have no seasons.

The sun's rays would be directly overhead of the equator all year long. Only a slight change would occur as the earth makes its slightly elliptical orbit around the sun. The earth is furthest from the sun about July 3; this point is known as the aphelion and the earth is 94,555,000 miles away from the sun. The perihelion takes place around January 4 when the earth is a mere 91,445,000 miles from the sun. When summer occurs in a hemisphere, it is due to that hemisphere receiving more direct rays of the sun than the opposite hemisphere where it is winter. In winter, the sun's energy hits the earth at oblique angles and is thus less concentrated. During spring and fall, the earth's axis is pointing sideways so both hemispheres have moderate weather and the rays of the sun are directly overhead the equator. Between the Tropic of Cancer and the Tropic of Capricorn (23.5° latitude south) there really are no seasons as the sun is never very low in the sky so it stays warm and humid ("tropical") year-round.

Only those people in the upper latitudes north and south of the tropics experience seasons. December solstice 2016 is the 21st | Astronomy Essentials | EarthSky December solstice 2016 is the 21st By Deborah Byrd in Astronomy Essentials | Earth | December 21, 2016 December solstice 2016 arrives on December 21 at 10:44 UTC. High summer for the Southern Hemisphere. For the Northern Hemisphere, the return of more sunlight! View larger. | Ian Hennes in Medicine Hat, Alberta, Canada, created this solargraphy between a June solstice and a December solstice. It shows the path of the sun during that time period. Late dawn. Early sunset. Short day. Long night. For us in the Northern Hemisphere, the December solstice marks the longest night and shortest day of the year. Meanwhile, on the day of the December solstice, the Southern Hemisphere has its longest day and shortest night. This special day is on Wednesday, December 21 at 10:44 UTC (December 21 at 4:44 a.m. CST).

No matter where you live on Earth’s globe, a solstice is your signal to celebrate. Follow the links below to learn more about the 2016 December solstice. Why doesn’t the earliest sunset come on the shortest day? Day and night sides of Earth on the December 2016 solstice Day and night sides of Earth at the instant of the December 2016 solstice (2016 December 21 at 10:44 Universal Time). The shadow line going through northwest South America depicts sunrise and the shadow line passing through Asia represents sunset. Note that the north polar region of Earth has 24 hours of night, while the south polar region basks in 24 hours of daylight. Image via Earth and Moon Viewer Sunlight on Earth, on the day of the winter solstice. The north polar region of Earth is in 24-hour darkness, while the south polar region is in 24-hour daylight. Gif via Wikimedia Commons. When is the solstice where I live? The solstice happens at the same instant for all of us, everywhere on Earth.

In 2016, the December solstice comes on December 21 at 4:44 a.m. CST. That’s on December 21 at 10:44 Universal Time . It’s when the sun on our sky’s dome reaches its farthest southward point for the year. At this solstice, the Northern Hemisphere has its shortest day and longest night of the year. To find the time in your location, you have to translate to your time zone. Click here to translate Universal Time to your local time. Just remember: you’re translating from 10:44 UT on December 21. For example, if you live in Perth, Australia, you need to add 8 hours to Universal Time to find out that the solstice happens on December 21, at 18:44 (6:44 p.m.) AWST (Australian Western Standard Time). Earth has seasons because our world is tilted on its axis with respect to our orbit around the sun. Image via NASA. What is a solstice?

The earliest people on Earth knew that the sun’s path across the sky, the length of daylight, and the location of the sunrise and sunset all shifted in a regular way throughout the year. They built monuments such as Stonehenge in England – or, for example, at Machu Picchu in Peru – to follow the sun’s yearly progress. But we today see the solstice differently. We can picture it from the vantage point of space. Today, we know that the solstice is an astronomical event, caused by Earth’s tilt on its axis, and its motion in orbit around the sun. Because Earth doesn’t orbit upright, but is instead tilted on its axis by 23-and-a-half degrees, Earth’s Northern and Southern Hemispheres trade places in receiving the sun’s light and warmth most directly. The tilt of the Earth – not our distance from the sun – is what causes winter and summer. At the December solstice, the Northern Hemisphere is leaning most away from the sun for the year. At the December solstice, Earth is positioned in its orbit so that the sun stays below the north pole horizon.

As seen from 23-and-a-half degrees south of the equator, at the imaginary line encircling the globe known as the Tropic of Capricorn, the sun shines directly overhead at noon. This is as far south as the sun ever gets. All locations south of the equator have day lengths greater than 12 hours at the December solstice. Meanwhile, all locations north of the equator have day lengths less than 12 hours. For us on the northern part of Earth, the shortest day comes at the solstice. After the winter solstice, the days get longer, and the nights shorter. It’s a seasonal shift that nearly everyone notices. Around the time of the winter solstice, watch for late dawns, early sunsets, and the low arc of the sun across the sky each day. Notice your noontime shadow, the longest of the year. Photo via Serge Arsenie on Flickr. Meanwhile, at the summer solstice, noontime shadows are short. Photo via the Slam Summer Beach Volleyball festival in Australia. Where should I look to see signs of the solstice in nature? Everywhere. For all of Earth’s creatures, nothing is so fundamental as the length of daylight.

After all, the sun is the ultimate source of all light and warmth on Earth. If you live in the northern hemisphere, you can notice the late dawns and early sunsets, and the low arc of the sun across the sky each day. You might notice how low the sun appears in the sky at local noon. And be sure to look at your noontime shadow. Around the time of the December solstice, it’s your longest noontime shadow of the year. In the Southern Hemisphere, it’s opposite. Dawn comes early, and dusk comes late. The sun is high. It’s your shortest noontime shadow of the year. EarthSky Facebook friend John Michael Mizzi saw this sunset from the island of Gozo (Malta), south of Italy. The earliest sunsets come a couple of weeks before the winter solstice. Why doesn’t the earliest sunset come on the shortest day? The December solstice marks the shortest day of the year in the Northern Hemisphere and longest day in the Southern Hemisphere. But the earliest sunset – or earliest sunrise if you’re south of the equator – happens before the December solstice. Many people notice this, and ask about it.

The key to understanding the earliest sunset is not to focus on the time of sunset or sunrise. The key is to focus on what is called true solar noon – the time of day that the sun reaches its highest point, in its journey across your sky. In early December, true solar noon comes nearly 10 minutes earlier by the clock than it does at the solstice around December 22. With true noon coming later on the solstice, so will the sunrise and sunset times. It’s this discrepancy between clock time and sun time that causes the Northern Hemisphere’s earliest sunset and the Southern Hemisphere’s earliest sunrise to precede the December solstice. The discrepancy occurs primarily because of the tilt of the Earth’s axis. A secondary but another contributing factor to this discrepancy between clock noon and sun noon comes from the Earth’s elliptical – oblong – orbit around the sun. The Earth’s orbit is not a perfect circle, and when we’re closest to the sun, our world moves fastest in orbit. Our closest point to the sun – or perihelion – comes in early January. So we are moving fastest in orbit around now, slightly faster than our average speed of about 30 kilometers (18.5 miles) per second.

The discrepancy between sun time and clock time is greater around the December solstice than the June solstice because we’re nearer the sun at this time of year. Solstice Pyrotechnics II by groovehouse on Flickr. The precise date of the earliest sunset depends on your latitude. At mid-northern latitudes, it comes in early December each year. At northern temperate latitudes farther north – such as in Canada and Alaska – the year’s earliest sunset comes around mid-December. Close to the Arctic Circle, the earliest sunset and the December solstice occur on or near the same day. By the way, the latest sunrise doesn’t come on the solstice either. From mid-northern latitudes, the latest sunrise comes in early January. The exact dates vary, but the sequence is always the same: earliest sunset in early December, shortest day on the solstice around December 21, latest sunrise in early January. And so the cycle continues. Bottom line: In 2016, the December solstice comes on December 21 at 4:44 a.m. CST. That’s December 21 at 10:44 UTC .

It marks the Northern Hemisphere’s shortest day (first day of winter) and Southern Hemisphere’s longest day (first day of summer). Happy solstice, everyone! 5 Things to Know About the Winter Solstice | TIME.com Science 5 Things to Know About the Winter Solstice The event marks the longest night in the Northern Hemisphere and the longest day in the Southern Hemisphere Send to Kindle KHALED DESOUKI / AFP / Getty Images The sun rises behind the Temple of Karnak Temple during the alignment of the winter solstice sunrise to the temple in the southern Egyptian city of Luxor on Dec. 21. Follow @TIMENewsfeed Behold! A year has passed since the great Mayan apocalypse of 2012 — newsflash: we’re all still here — and the winter solstice is again upon us. The solstice marks the shortest day of the year for dwellers in the Northern Hemisphere, and the longest day of the year for those south of the equator. But that doesn’t just mean darkness will cast a great shadow over the Northern Hemisphere. Leading up to the solstice, the sun’s highest point appears closer to horizon each day, which means the days get shorter and the nights get longer.

During the solstice, the sun’s position relative to Earth seems to pause (solstice means “stationary sun”), and from that day forward appears to inch northward, meaning more sunlight for those of us in the north. Here’s a look at why you should care about today’s astronomical event. What is it? The 23.5 degree tilt in Earth’s axis of rotation creates a rise and fall appearance of the sun over the course of a year. During the winter solstice, the Northern Hemisphere is pointed at its furthest distance from the sun, bringing less light and colder temperatures. The winter solstice occurs at a specific time, not just day. This year, at 12:11 p.m. EST on Saturday, Dec. 21, the sun shone directly over the Tropic of Capricorn, the farthest south the sun reaches. In the Southern Hemisphere, it was the longest day of the year. So then what happens? After the solstice occurs, days grow longer for north of the equator, as the sun appears farther above the horizon. This movement culminates in the longest day of the year on June 21. Is it related to Christmas? Sort of.

There’s no date in the Bible specifically pointing to Dec. 25 as the birth of Jesus Christ, so some experts believe the Christian church selected the date several centuries later, tying it to the Roman holiday Dies Natalis Solis Invictus, or the Birthday of the Unconquerable Sun. The winter solstice serves a turning point in many cultures, which is why it was tied to the Mayan apocalypse scare that marked the end of the calendar and to some believers, the end of the world. Just how short is the day? North America will only see nine hours and 32 minutes of daylight during the solstice, and 14 hours and 28 minutes of nighttime. But the winter solstice doesn’t always happen at the same time. Next year northern dwellers can brace for the solstice at 11:03 p.m. In 2015 it will occur on Dec. 22. What are other important dates for the sun? The summer solstice occurs on June 21, the longest day of the year in the north. On March 21 and Sept.

21, Earth’s equator passes the center of the sun, which are known as “equinoxes.” These two dates mark the point at which hours of day and night are nearly equal. This post has been updated for clarity. Subscribe Popular Among Subscribers Sunrise and Sunset Times Near the Solstices Sunrise and Sunset Times Near the Solstices Sitemap The period within a few weeks of the winter solstice in late December is the darkest time of the year for northern latitudes. Not only does the Sun traverse its lowest arc across the sky at this time, but in many places the Sun sets before the end of a normal workday and rises after many people have already started their daily routines. At latitude 40° north, earliest sunset occurs around December 8 each year, and latest sunrise occurs around January 5. The day with the least amount of daylight is the winter solstice, the first day of winter, on or about December 21. Why are not all these dates the same? The answer is not trivial, but on this page we have tried to provide as simple an explanation as possible. It has to do with the fact that our clocks and the Sun do not keep the same kind of time.

Below are three explanations, with increasing detail. Choose the one that most fits your level of interest! By the way, a similar situation occurs at the summer solstice, for the same basic reason, though the effect is not as extreme. Solstice occurs around June 21, but at latitude 40° north the earliest sunrise occurs around June 14 and the latest sunset occurs around June 28. The changing times of sunrise and sunset are probably more noticeable in the winter months, because sunrise and sunset occur when we are more likely to be paying attention — when we're starting our day and during the evening rush hour. Also, most of us don't like the short period of daylight then and are looking forward to getting more of it. Note: These explanations are written from a northern-hemisphere perspective. The situation is similar in the southern hemisphere. Getting Technical... A Thumbnail Explanation Our clocks do not keep Sun time. Time measured by the position of the Sun in the sky is somewhat variable over the course of a year, but our clocks keep a uniform approximation to Sun time with each day exactly 24 hours long. One consequence of this is that sundials usually seem to be wrong; that is, they do not keep clock time.

The times of sunrise and sunset, measured by the clock, are also affected by the difference between the two kinds of time. Although the length of daylight is shortest on the winter solstice, around December 21, the dates of earliest sunset and latest sunrise are, somewhat surprisingly, not on this date. Why is that? The reason can be traced to the fact that the difference between Sun time and clock time is rapidly changing in December and January. The Sun runs slow compared to clock time then, so the times of both sunrise and sunset tend to be a bit late according to the clock, delayed from one day to the next by up to a half minute. Consequently, the time of sunset begins to shift later at an earlier date than we would expect (so that the earliest sunset is in early December), and the time of sunrise doesn't begin to shift earlier until a later date than we would expect (so that the latest sunrise is in early January). Expanding a Bit . . . The changing position of the Sun in the sky over the course of a day is mainly an effect of the Earth's rotation on its axis, which is quite uniform to a small fraction of a second.

However, where the Sun appears in the sky at any given time is also affected by the position of the Earth in its orbit around the Sun. For reasons explained elsewhere , time kept by the Sun is not uniform throughout the year. Some solar days (the interval between the instants when the Sun is due south in the sky) are longer or shorter than 24 hours by as much as a half minute. On the other hand, our clocks keep civil time, with a uniform rate equal to the solar rate averaged over the entire year, with each day exactly 24 hours long. Therefore, even very carefully made sundials located in the middle of a time zone do not keep clock time. Regardless of what kind of time we use, the day with the shortest overall length of daylight is always the winter solstice, on or about December 21, when the Sun appears to move along its most southern track in our sky. If we kept time by the Sun, and not mechanical or electrical clocks, the date of the earliest sunset and the date of the latest sunrise would also be the date of the winter solstice (we owe this insight to Guy Ottewell, creator of the annual Astronomical Calendar ).

This is what most people (even astronomers!) would expect: the solstice, earliest sunset, and latest sunrise should "naturally" occur on the same date. But our clocks do not run on Sun time. In fact, actual solar days from mid November to early February are each longer than 24 hours by anywhere from a few seconds to a half minute. In other words, the Sun moves with what seems to be a very slightly slower-than-average apparent westward daily motion in the sky (measured with respect to our uniform clock time) during that part of the year. This tends to delay both sunrises and sunsets as measured by the clock. As a result, the times of sunset start moving later before the date of the solstice (that is, the date of earliest sunset occurs early) and the times of sunrises do not start moving earlier until after the date of the solstice (the date of latest sunrise occurs late). How much these two dates differ from that of the winter solstice depends on your latitude; at 40° north latitude, these dates are about two weeks from the solstice, earlier or later, respectively. The range of these dates is wider at lower latitudes and narrower at higher latitudes.

The Long Story The Earth's seasons are caused by three factors: The Earth orbits the Sun once a year in a nearly circular orbit. The Earth's axis of rotation (the straight line through the center of the Earth between the north and south poles) is not perpendicular to the plane of the Earth's orbit. The Earth's axis is tilted by about 23.4° from the the direction perpendiular to the orbital plane. The orientation of the Earth's axis in space remains nearly constant even as the Earth revolves around the Sun. It always points in the general direction of the star Polaris. The result is that when the Earth is on one side of its orbit, the south pole is tilted toward the Sun (by as much as 23.4°) and the southern hemisphere experiences summer. Six months later, when the Earth is on the opposite side of its orbit, the north pole is tilted toward the Sun (by as much as 23.4°) and the northern hemisphere experiences summer.

(Views of the Sun's illumination on the Earth on any date are available here .) What we see from our viewpoint in the Earth's northern hemisphere is that the Sun's apparent daily track across the sky is much higher (that is, more northerly) in summer, and lower (more southerly) in winter. From horizon to horizon, the Sun's track is longer in summer and shorter in winter; so that in summer, sunrises are much earlier and sunsets are much later than in winter. See, for example, the graphic below, or this photograph of the Sun's paths through the sky at different times of the year. The Sun's track across the sky is much shorter and lower in the winter than in the summer. During the early fall, as the Sun moves lower in the southern sky, sunrises get later, and sunsets earlier.

So we are used to the fact that the length of daylight is significantly longer in summer than winter, and most of us know that the "longest day" (that is, the day when the Sun is above the horizon the longest) is the summer solstice, around June 21, when the Sun has reached its most northerly and longest track in our sky; and the "shortest day" is the winter solstice, around December 21, when the Sun has reached its most southerly and shortest track in our sky. It would make sense, then, for the summer solstice to also be the date at which sunrise is earliest and sunset is latest; and for the winter solstice to be the date when sunrise is latest and sunset is earliest. However, that is not what happens! Nature sometimes defies our expectations. The local meridian is a great circle passing through the celestial poles and through the zenith of an observer's location on the planet. Image Credit: Daniel V. Schroeder And that is because we have not talked about one other factor in sunrise and sunset times that is not at all obvious.

It is that the Sun moves across the sky, in its apparent daily track, at slightly different rates at different parts of the year. Most of the Sun's east-to-west apparent motion in the sky is caused, of course, by the rotation of the Earth, which is quite uniform (to milliseconds per day). But a small part of the Sun's apparent daily motion depends on the position of the Earth in its orbit around the Sun. This component of the Sun's apparent motion varies by a small amount over the course of a year due to the elliptical shape of the Earth's orbit and to the tilt of the Earth's axis. The details of this variation are explained in detail elsewhere , but the overall effect is that the Sun's total apparent angular rate as it moves across the sky varies by as much as 0.07% from one part of the year to another. That doesn't seem like much, but it means that the length of the solar day, measured by successive transits of the Sun across the local meridian (successive noons on a sundial), can be as much as a half minute different from 24 hours, one way or the other. Therefore, we effectively have two kinds of time.

Time kept by the Sun's motion in the sky (apparent solar time) is not a uniform kind of time, like that kept by our clocks. Mechanical or electrical clocks run at a uniform rate, and that rate has been set to correspond to the average rate of the Sun across the sky over the course of the year. So our clock time (neglecting, of course, daylight time shifts) is a form of what is called mean solar time. Every day by our clocks has 24 hours exactly, but each day of apparent solar time can be different from 24 hours by as much as a half minute. At some parts of the year, the two kinds of time can accumulate a difference of as much as 16 minutes, which is one reason why sundials hardly ever seem to be correct. We are comparing apples and oranges: Sun time is not clock time. Sundials hardly ever give the same time as our clocks. Sun time (technically, apparent solar time) is not the same as clock time (a type of mean solar time). The difference affects not only the time kept by sundials, but also the clock times of sunrise and sunset.

Near both the winter and summer solstices, the changing difference between the two kinds of time has more effect on the times of sunrise and sunset than the slowly changing geometry of the Sun's track in the sky. The two effects on sunrise and sunset time might be called, succinctly, the "geometric effect", which is the variation in the length of the Sun's track across the sky as a function of the season; and the "clock effect", caused by the fact that the Sun keeps its own time, which on any given day may be somewhat different from what our clocks say. Notice that the geometric effect tends to work oppositely on sunrise and sunset times; for example, in the fall, when the length of the Sun's track in the sky is getting shorter, sunrises get later and sunsets earlier. On the other hand, the clock effect works the same way on all Sun phenomena—if the Sun is "late" on a particular day (compared to the day before), then sunrise, sun transit (sundial noon), and sunset will all be "late" by the same amount. The technical name for the clock effect is the Equation of Time .

During the early fall, the geometric effect dominates the change in rise and set times; from one day to the next, the Sun is shifting ever more southward in the sky, and at mid northern latitudes, the total length of daylight (sunset time minus sunrise time) gets shorter by several minutes every day (see the Duration of Daylight/Darkness Table for one Year ). For example, on October 15 at 40° north latitude, the Sun is above the horizon for 2½ fewer minutes than on the previous day. Based on that effect alone, we would expect sunrise to be later, and sunset earlier, by 1¼ minutes compared to the day before. The clock effect at this time of year is a rather minor factor; considering the clock effect alone (which is the same for all latitudes), the Sun is ¼ minute earlier in all of its phenomena on October 15 than it was on October 14. So the geometric effect dominates at this time of year in determining the times of rise and set. As the fall progresses, though, several things change. For one thing, as we get into November, the geometric effect becomes less of a factor in the day-to-day changes.

The Sun's southerly migration in the sky slows considerably as we get into December. (It comes to a stop at the winter solstice, around December 21, after which the Sun begins its slow march northward.) Also, around November 3, the clock effect changes sign and the Sun begins to run later and later each day. In fact, as the magnitude of the geometric effect is ramping down, the magnitude of the clock effect is ramping up. On December 15, the Sun is above the horizon for only ½ minute less than on the previous day, so sunrise will be later, and sunset earlier, by only ¼ minute compared to December 14, based on the geometric effect alone. But the clock effect shifts all Sun phenomena about ½ minute later by our clocks on December 15 than on December 14. So, adding the two effects together, the times of both sunrise and sunset on December 15 are later than on December 14. Evidently, we have already passed the date of earliest sunset, and the solstice has not yet occurred.

The date of earliest sunset, about December 8 at a latitude of 40° north, is the date when the clock effect takes over from the geometric effect in having the greater influence on the times of sunset. The date of latest sunrise is determined by similar considerations. As we have seen, in late December, both sunrise and sunset occur later each day. But after the solstice, the geometric effect, considered alone, tends to shift sunrise earlier as the Sun's daily track in the sky becomes more northerly and longer. But that effect is weaker than the clock effect—at least, for a while. Eventually, the geometric effect overcomes the clock effect's tendency to move all Sun phenomena later each day. The date of latest sunrise is therefore the date, after the solstice, when the geometric effect equals the clock effect in magnitude. That date is about January 5 at a latitude of 40° north. After that, the geometric effect takes over and the times of sunrise move consistently earlier. Therefore, between the dates of earliest sunset and latest sunrise, the clock effect dominates the geometric effect in determining the times of sunrise and sunset for a given latitude.

The reason the dates of earliest sunset and latest sunrise depend on latitude is that the geometric effect is a greater factor at high latitudes. There, the length of the Sun's track across the sky varies more throughout the year. The clock effect is the same for all latitudes. So at higher latitudes, the dates of earliest sunset and latest sunrise are closer to the solstice; i.e., closer to when we expect them to be, based on the geometry of the Sun's seasonal motion. At the equator, there is no geometric effect at all—the Sun's daily track above the horizon is always exactly half a circle. The clock effect completely determines when sunrise and sunset occur there. Earliest sunset occurs around November 2 and latest sunrise occurs around February 11. But the total variation in sunrise or sunset times at the equator, over the year, amounts to only about a half hour. Returning to the middle northern latitudes, sunrise and sunset times near the summer solstice are influenced by the geometric and clock effects in the same way as those near the winter solstice. However, the magnitude of the clock effect is not as large in June as in December.

The date of earliest sunrise occurs before the solstice and the date of latest sunset occurs after. Getting Technical . . . The geometric effect mentioned above is a function of the Sun's declination, the term that astronomers use for the angle that the center of the Sun makes with the plane of the Earth's equator, as viewed by a fictitious observer at the center of the Earth. As the Earth orbits the Sun, the Sun's declination goes from +23.4° at the summer solstice to −23.4° at the winter solstice, and back again, passing through declination zero (that is, through the equatorial plane) at the two equinoxes. On the surface of the Earth, the length of time that the center of the Sun is above the horizon at any given latitude, in hours, is given approximately by ts = 2/15 arccos (–tan φ tan δ) where φ is the latitude and δ is the Sun's declination. It is assumed that the value of the arccos function is given in degrees. This formula works only for latitudes between the arctic and antarctic circles.

The time ts changes over the course of a year as the Sun's declination δ changes. This simple formula neglects (1) atmospheric refraction at the horizon, (2) the small variation in the Sun's apparent rate of east-west motion across the sky due to the "clock effect", and (3) the small changes in the Sun's declination that occur during most days. In particular, it's worth noting here that sunrise and sunset are defined to occur when the top of the Sun (its upper limb) appears to be on the horizon, with atmospheric refraction taken into account, so the time between sunrise and sunset is always greater than ts by at least a few minutes. As mentioned above, astronomers call the clock effect the Equation of Time , which is the difference between apparent solar time and mean solar time. Civil time—what our clocks read—is a form of mean solar time on the local time zone's defining meridian (each time zone is based on a meridian with a longitude evenly divisible by 15°). Officially, civil time is an integral number of hours offset from Coordinated Universal Time , abbreviated UTC. The hour offset depends on the time zone and whether daylight time is in effect.

UTC is the successor to Greenwich Mean Time and is synchronized worldwide to very high precision. The dates of earliest sunset and latest sunrise are the dates before and after the winter solstice when, at a given latitude, the magnitude of half the daily change in ts equals the magnitude of the daily change of the Equation of Time. Half the daily change in ts is used because the geometric (or declination) effect is divided equally between sunrise and sunset. On the other hand, the change in the Equation of Time shifts the timing of all Sun phenomena by its full amount. Approximate formulas for the Sun's declination and the Equation of Time are given on our page about computing Approximate Solar Coordinates . A table listing both the Sun's declination and the Equation of Time, for each day of the year, is printed in the annual booklet Astronomical Phenomena . The values in the table change from year to year but not by much. You can get the same information online, for a range of specific dates, here (be sure to select Apparent Geocentric Right Ascension and Declination for the Sun).

If you use this data to make a graph of the Sun's declination as the y-axis and the Equation of Time as the x-axis, you obtain a figure-8 curve for the year called the analemma . The analemma is the pattern of Sun images that you would obtain if, using a fixed camera and a multiple exposure setting, you recorded the Sun at noon clock time on every day of the year that it was clear; see, for example this picture .

Question: In the southern hemisphere, when does the winter solstice occur?
Answer: June