Shining Light on the Summer Solstice: Unveiling the Longest Day of the Year
Longest Day of the Year Marked on Summer Solstice of 2021
By Jana Zeh
More Info Facebook Twitter WhatsApp Email Print Copy Link
The summer solstice, the year's longest day, signals the start of summer in the Northern Hemisphere. But what causes the varying length of the longest day across the Northern Hemisphere and why doesn't it always happen on June 21? Let's delve into the fascinating secrets behind this astronomical event.
Northern Hemisphere: A Tale of Varying Daylight Hours
Contrary to popular belief, the longest day of the year is not the same length everywhere in the Northern Hemisphere on the day of the solstice. Data from Germany reveals this misconception—with Munich experiencing 16 hours and 7 minutes of daylight and Kiel enjoying 17 hours and 17 minutes. Only at the equator are days and nights always 12 hours each. The further north you travel, the more pronounced the lengthening of the longest day becomes. For example, in Helsinki, the sun rises at 3:54 AM and sets at 10:50 PM, granting the city almost 19 hours of daylight. Even as the sun sets briefly, it doesn't get completely dark in the Finnish capital.
Twin Solstices: A Global Phenomenon
The summer solstice in the Northern Hemisphere has an interesting counterpart—the winter solstice on the Southern Hemisphere. As the longest day of the year begins in the Northern Hemisphere, the longest night of the year emerges on the Southern Hemisphere. This year's solstice on June 21 marks the astronomical event's high point in the Northern Hemisphere at 4:42 AM MESZ, with the sun reaching its zenith in its annual path. Simultaneously, from the Southern Hemisphere, the sun reaches its lowest point at the horizon, marking the beginning of winter in that hemisphere, where days will gradually grow longer and nights shorter.
Off Venture: A Leap From June 21
While the solstices often fall on June 21 and December 21, there's a twist in the calendar tale. Although the solstice time is astronomically precise, the date can vary depending on time zones on Earth. For instance, if the summer solstice falls on June 21 in Europe, it's still June 20 in some parts of America at the same time. Leap years, which occur every four years, can also cause a discrepancy in the solstice calendar, shifting the dates to June 20 or June 22 and even December.
Polar Phenomena: Beyond the Arctic Circle
In high latitudes north of the Arctic Circle, the Midnight Sun phenomenon occurs—where the sun doesn't set for weeks around the summer solstice. But, in these latitudes, several weeks of polar night occur in winter, with the sun never rising above the horizon, making it dark even during the day.
Spiraling Away From the Sun
Surprisingly, Earth is further from the Sun when the summer solstice occurs in the Northern Hemisphere than during the winter solstice, conflicting with the idea that summer should be hotter due to Earth being closer to the Sun. Earth's slightly elliptical orbit causes it to be closer and further from the Sun at different times, but the Sun's warmth depends on its angle of incidence rather than the distance to the Sun. The summer heat is a result of the steeply angled sunlight warming the underlying areas the most.
Source: ntv.de
- Astronomy
- Sun
- Earth
- The variation in the length of the longest day across the Northern Hemisphere, as observed in cities like Munich and Kiel, is a testament to the intricacies of both environmental-science and space-and-astronomy.
- In the realm of science, understanding the causes behind the summer solstice, such as Earth's elliptical orbit and the tilt of its axis, helps us better appreciate the weather patterns associated with this phenomenon.
