Why does the southern hemisphere experience winter and Summer Solstice in difference in times?

Answer the following questions briefly.

(a) What is the angle of inclination of the Earth’s axis with its orbital plane?

(b) Define rotation and revolution.

(c) What is a leap year?

(d) Differentiate between the Summer and Winter Solstice.

(e) What is an equinox?

(f) Why does the Southern Hemisphere experience Winter and Summer Solstice in different times than that of the Northern Hemisphere?

(g) Why do the Poles experience about six months day and six months night?

(a) The angle of inclination of the Earth’s axis with its orbital plane is 66½°.

(b) Rotation is the movement of the Earth on its axis.

Revolution is the movement of the Earth around the Sun in a fixed path or orbit.

(c) Earth takes 365¼ days to revolve around the Sun. However, for the sake of convenience, we consider a year as consisting of 365 days. The six hours (1/4th of 24 hours) that are ignored make one day (24 hours) over a span of four years. This surplus day is added to the month of February. Thus, every fourth year, February has 29 days, and such a year (with 366 days) is known as a leap year.

(d)

(e) Equinox is the position of the Earth when the rays of the Sun fall directly on the Equator. At this position, neither of the Poles is tilted towards the Sun. As a result, the entire Earth has equal days and equal nights.

(f) When the North Pole is tilted towards the Sun, the Northern Hemisphere experiences Summer Solstice. At this time, since the South Pole is tilted away from the Sun, the Southern Hemisphere experiences Winter Solstice.

When the North Pole is tilted away from the Sun, the Northern Hemisphere experiences Winter Solstice. At this time, since the South Pole is tilted towards the Sun, the Southern Hemisphere experiences Summer Solstice.

(g) The Poles experience about six months of day and six months of night because of the tilt of the Earth on its axis. Because of this tilt, each Pole is tilted towards and away from the Sun for about six months each.

When the North Pole is tilted towards the Sun, it experiences continuous daylight for six months. It is night for the same time period at the South Pole. These conditions are reversed when the South Pole is tilted towards the Sun.

Tick the correct answers

(a) The movement of the Earth around the Sun is known as

(b) Direct rays of the Sun fall on the Equator on

(c) Christmas is celebrated in summer in

(d) Cycle of seasons is caused due to

(a) The movement of the Earth around the Sun is known as

(i) Rotation

(ii) Revolution

(iii) Inclination

(b) Direct rays of the Sun fall on the Equator on

(i) 21 March

(ii) 21 June

(iii) 22 December

(c) Christmas is celebrated in summer in

(i) Japan

(ii) India

(iii) Australia

(d) Cycle of seasons is caused due to

(i) Rotation

(ii) Revolution

(iii) Gravitation

Fill in the blanks.

(a) A leap year has ________ number of days.

(b) The daily motion of the Earth is _________.

(c) The Earth travels around the Sun in _________ orbit.

(d) The Sun’s rays fall vertically on the Tropic of _________ on 21st June.

(e) Days are shorter during _________ season

(a) A leap year has 366 number of days.

(b) The daily motion of the Earth is rotational.

(c) The Earth travels around the Sun in a fixed elliptical orbit.

(d) The Sun’s rays fall vertically on the Tropic of Cancer on 21st June.

(e) Days are shorter during winter season.

This year, the northern summer solstice falls on June 21 at 5:13 a.m. EDT (June 21 at 9:13 UT). South of the Equator, this same moment marks the unofficial beginning of winter. Solstices occur at the same time around the world, but their local times vary with time zones. 

Traditionally, summer and winter solstices helped mark the changing of the seasons—along with their counterparts, the spring and autumnal equinoxes. However, today’s meteorologists officially use temperature records instead to draw lines between the seasons. So what exactly are solstices—and how have they been celebrated throughout history? Here’s all you need to know.

(Here's the difference between astronomical and meteorological seasons.)

What are solstices?

Solstices occur because Earth’s axis of rotation is tilted about 23.4 degrees relative to Earth's orbit around the sun. This tilt drives our planet's seasons, as the Northern and Southern Hemispheres get unequal amounts of sunlight over the course of a year. From March to September, the Northern Hemisphere is tilted more toward the sun, driving its spring and summer. From September to March, the Northern Hemisphere is tilted away, so it feels like autumn and winter. The Southern Hemisphere's seasons are reversed.

On two moments each year—what are called solstices—Earth's axis is tilted most closely toward the sun. The hemisphere tilted most toward our home star sees its longest day, while the hemisphere tilted away from the sun sees its longest night. During the Northern Hemisphere’s summer solstice—which always falls around June 21—the Southern Hemisphere gets its winter solstice. Likewise, during the Northern Hemisphere's winter solstice—which always falls around December 22—the Southern Hemisphere gets its summer solstice.

You can also think about solstices in terms of where on Earth the sun appears. When it’s a summer solstice in the Northern Hemisphere, the sun appears directly over the Tropic of Cancer, the latitude line at 23.5 degrees North. (That’s as far north as you can go and still see the sun directly overhead.) During the Northern Hemisphere’s winter solstice, the sun appears directly over the Tropic of Capricorn, the Tropic of Cancer’s southern mirror image.

Earth is not the only planet with solstices and equinoxes; any planet with a tilted rotational axis would see them, too. In fact, planetary scientists use solstices and equinoxes to define "seasons" for other planets in our solar system.

It's worth noting, though, that other planets' seasons don't climatically equal those on Earth for a few reasons. First, planets vary in their axial tilts: Venus's axis of rotation is tilted by just three degrees, so there's much less seasonal difference between the Venusian summer and winter solstices than those on Earth. In addition, planets such as Mars have less circular orbits than Earth's, which means that their distances from the sun vary more dramatically than ours do, with correspondingly bigger effects on seasonal temperature.

Earth’s axial tilt plays a much bigger role than its near-circular orbit in governing annual seasons. Earth makes its closest annual approach of the sun about two weeks after the December solstice, during the Northern Hemisphere's winter. Earth is farthest from the sun about two weeks after the June solstice, during the Northern Hemisphere's summer.

The solstice through history

For millennia, cultures around the world have devised ways to celebrate and revere these celestial events—from building structures that align with the solstice to throwing raucous festivals in its honor.

Though the purpose of the enigmatic English structure Stonehenge remains unknown, this 5,000-year-old monument has a famously special relationship with the solstices. On the summer solstice, the complex’s Heel Stone, which stands outside Stonehenge’s main circle, lines up with the rising sun.

In Egypt, the Great Pyramids at Giza appear to be aligned with the sun as well. When viewed from the Sphinx, the sun sets between the pyramids of Khufu and Khafre during the summer solstice—though it remains unclear precisely how the ancient Egyptians oriented it this way.

Many cultures have found unique ways to mark the summer solstice. The traditional Scandinavian holiday of Midsummer welcomes it with maypole dancing, drinking, and romance. During the Slavic holiday of Ivan Kupala, people wear floral wreaths and dance around bonfires, while some plucky souls jump over the fires as a way of ensuring good luck and health. In a more modern tradition, the people of Fairbanks, Alaska, swing in the summer solstice with a nighttime baseball game to celebrate the fact that they can get up to 22.5 hours of daylight in the summer. The Midnight Sun Game has been played since 1906.

The winter solstice has had its share of celebrations, too. On June 24, in time with the Southern Hemisphere’s winter solstice, the Inca Empire celebrated Inti Raymi, a festival that honored the Inca religion’s powerful sun god Inti and marked the Inca new year. The festival is still celebrated throughout the Andes, and since 1944, a reconstruction of Inti Raymi has been staged in Cusco, Peru, less than two miles from its Inca Empire home. Ancient Romans celebrated the winter solstice with Saturnalia, a seven-day festival that involved giving presents, decorating houses with plants, and lighting candles. And Iranians celebrate Yalda in December. The festival—a mainstay since Zoroastrianism was Iran’s dominant religion—traditionally honors the birth of Mithra, the ancient Persian goddess of light.

Misconceptions about the solstices

If solstices mark the brightest and darkest days of the year, why don’t temperatures reflect that?

In short, it’s because it takes time for Earth’s land and water to heat up and cool down. In the U.S., the year’s coldest temperatures set in after-mid January, roughly a month after the Northern Hemisphere’s winter solstice. Likewise, thermometers hit their high in the U.S. in July and August, weeks after the summer solstice.

Some believe, too, that since Earth’s rotation is slowing down, each new solstice sets a new record for daytime length. But that’s not the case.

It’s certainly true that Earth’s rotation has slowed over billions of years, as Earth loses angular momentum to our planet’s tides. Growth lines on fossil corals show that more than 400 million years ago, days on Earth lasted less than 22 hours.

But Earth’s gradual slowing down isn’t the only factor at play. Picture a figure skater twirling on their skates; they can speed up or slow down their twirls by how much they tuck in their limbs. In much the same way, changes in the distribution of Earth’s mass—from the winds of El Niño to the melting of Greenland’s ice—can subtly tweak our planet’s rotation rate.

Taking all this into account, it’s thought that the longest day since the 1830s occurred sometime in 1912. It lasted less than four milliseconds longer than the recent average.