There would also be no need to mark the equinoxes or solstices. The two solstices occur in June (20 or 21) and December (20 or 21). (21 or 22). On these days, the Sun's path in the sky is the furthest north or south of the Equator. The equinoxes occur in March (about March 21) and September (about September 23). These times mark the balance between winter and spring.
The sun enters Aries on February 14th and leaves it on Pisces on April 15th. This is known as the zodiacal year. However, due to the fact that we only get 12 months out of every zodiacal year, we need to add or subtract some time from this date depending on where in the zodiac you are each month. For example, if you were to leave Aries on February 14th at midnight, you would arrive in Taurus on March 21st at midnight. Because it is only for one day, this is called a "solstice." If you left Aries on April 15th at midnight, you would arrive in Cancer on May 20th at midnight. Because it is longer than one day, this is called an "equinox."
In short, the two solstices occur when the sun is at its northernmost or southernmost point in the sky relative to the equator, and the two equinoxes occur when the sun is exactly over the equator.
The northern hemisphere summer and southern hemisphere winter seasons begin and end on these days.
The equinoxes are times of balance, when day and night are equal in length. The equinoxes occur either in March or September, depending on where you are on Earth. At the equinoxes, the Sun is right over the equator, its rays are parallel to the ground, and daytime and nighttime are the same length. The spring equinox occurs when the Northern Hemisphere is in spring and the fall equinox when the Southern Hemisphere is in autumn.
These are the only times when we can see all parts of the sky. At other times, the horizon limits our view; for example, we cannot see straight up without aid from a high mountain or tree.
The reason the equinoxes and solstices are important landmarks is that they mark changes in the Earth's orientation with respect to the Sun. During a solar eclipse, the Earth's shadow falls on the Moon; at mid-month, the Earth passes through the center of the Sun.
These are the days when the Sun is directly above the equator, resulting in equal lengths of day and night. Every other day is not a true equinox; on those days, either the morning or evening twilight lasts for several hours instead of just a few.
Equinoxes occur at the same time every year, which makes them great markers for dating events. For example, the first stone tool was used by humans about 2 million years ago, which dates it to within a few hundred thousand years of each other around three different equinoxes. Before tools were invented, our ancestors marked their calendar using natural phenomena such as sunset and sunrise. The idea of marking days with something artificial like rocks or sticks happened later on.
People have been making maps for thousands of years using the patterns of landmasses against the backdrop of the night sky. At any given moment, there are two points on Earth that face each other from opposite directions: one is the North Pole, the other is the South Pole. These poles always stay in exactly the same place within Earth's surface, but the direction they point can change over time.
At any given moment, half of Earth is facing the Sun, while the other half is in darkness.
SOLSTICES AND EQUINOXES
|Vernal Equinox||March 20||0°|
|Summer Solstice||June 21||23.5°N|
|Autumnal Equinox||September 23||0°|
|Winter Solstice||December 22||23.5°S|
The spring and fall equinoxes occur on March 22 and September 21, respectively. These are points in the Earth's orbit where the Sun appears straight above the equator. The length of the day and night is about equal, at roughly 12 hours. At these times there are no differences in altitude between the center of the earth and its surface.
The equinoxes mark the beginning of spring and autumn. During this period of time, which is about six months out of the year, the weather is generally more stable than during other parts of the year. This is because there is less difference between the temperatures of the atmosphere above land areas and sea surfaces during spring and autumn than there is at other times of the year.
Equinoxes occur when the Earth is positioned so that the axis about which it spins is directly over a point on the Earth's surface. At other times this axis is inclined to the ground, making summer and winter seasons possible.
During an equinox, all places on Earth experience approximately 12 hours of daylight and 12 hours of darkness. Night falls as soon as the sun goes down and doesn't come up until after it has returned again. Daylight is present everywhere around the world at the same time.
In addition to marking the start of spring and autumn, the equinoxes also signal the start of solar and lunar years.
(The seasons are inverted in the Southern Hemisphere.) All around the world, people celebrate with parades, festivals, and rituals relating to sunlight, night, and time.
The solar equinoxes don't happen at the same time every year. They vary between March 20 and 22 this year, due to the presence of the moon. However, they tend to fall on about the same date each year, which is why they're important markers for astronomers and weather forecasters.
The lunar equinox occurs on September 28 this year. This is the day when the center of Earth's shadow falls on the face of the moon. Before this happened, the moon was getting more light from the sun during its waning phase, but after this happens, it starts getting more light from the sun during its waxing phase.
Equinoxes are important points in a person's life cycle. At the solar equinox, we start out the season of growth and development, while at the lunar equinox, we start out the season of decline and death. It's not that simple though, as some parts of the world experience these events at different times of the year.