Equinox and Solstice

Equinox and Solstices, are two reasons why the earth has different seasons. Equinox is when the length of day and night are the same. Solstice is when people on earth experience long days and nights. Before looking at the differences between Equinox and solstice, let us look in detail at the equinox and solstice and what happens during that time.

Equinox 

Equinox is that time of the year when the daytime and the nighttime are equal. This event takes place two times a year, i.e., on 20 March and 23 September. An equinox occurs because the plane of the earth’s equator passes directly from the centre of the sun’s geometric plane, which means that the centre of the visible portion of the sun is falling directly over the equator.

In the Northern hemisphere, the Equinox of March is the vernal equinox, while the Equinox of September is called the Autumnal equinox. The reverse is true in the case of the southern hemisphere. The date of an equinox may vary due to various factors, including the leap year.

Ignoring the hemispheres, the general names of both the equinoxes are Northward equinox and southward equinox, respectively. As the name suggests, a Northward equinox would mean that the Celestial equator is being crossed by the solar declination in the northward direction and vice versa.

The northward equinox marks the beginning of spring in most regions and is celebrated as the new year per the Hindu, Persian, and Iranian calendars. The southward equinox marks the beginning of autumn. The equinoxes are that time of the year when an equal amount of sunlight illuminates both the hemispheres of the earth. This is also why during an equinox; the sun appears to rise at one rotational pole of the Earth and appears to set for an observer at the opposite rotational pole. This implies that equinox is that time of the year when the rays of the sun fall directly on the equatorial plane.

One prominent effect of an equinox is that on days falling around an equinox, the sun is directly behind the earth and hence the high energy leads to disabling and an overload on the reception circuits of geostationary satellites. These effects can last for a duration varying between a few minutes to an hour.

Solstice 

An event that happens when the sun seems to reach its most northerly or southerly expedition relative to the celestial equinoctial line on the celestial sphere is known as a solstice. The word solstice is derived from the Latin language. In a year two solstices occur. One on the 21st of June and the second on the 21st of December. In several countries, the seasons are specified by the citation to the solstice and the equinoxes. Earth’s latitude acquaintance solstice in varied ways. At poles, the solstice is a maximum of radical exposure to sunlight, while at the Equator, solstices are hardly noted at all. 

Summer solstice- The day of the solstice is either of the hemispheres which have the most sunlight of the year. 

Winter solstice- The day of the solstice has the least amount of sunlight of the year in either of the hemispheres except the equator. 

Solstices are called ‘June Solstice’ or ‘December Solstice.’ In June, the sun reaches its highest position in the sky for any observer on the North pole; this day is known as June solstice day. Likewise, in December, the sun reaches its highest position in the sky for any observer on the south pole; this day is known as the December solstice day. At the solstice time, one can say that the sun is standing. Throughout history, the winter solstice in many cultures has been a significant time of the year. It moreover depicts the symbolic demise and rebirth of the sun.

During the June solstice, sun declination is about 23.5°N, and the December solstice is 23.5°S. As a result of 23.5° Earth’s axial tilt, either the Southern or Northern Hemisphere acquires the extreme intensity of the sun’s rays. The summer solstice is the year’s lengthiest day, and the winter solstice is the shortest day of the year. 

Difference between Equinox and Solstice

Conclusion

Equinox and solstice are astronomical milestones. During the equinox, the earth is directly beneath the sun or above the sun. Solstice is when the sun is at the highest point away from earth. In this article, we learned about equinox and solstice, the dates on which they can be expected, and the difference between them. A solstice is an important event for farmers, as it marks the season for growing crops.