The Summer Solstice (mid-summer in the northern hemisphere) occurs on about 21 June when the Sun’s declination reaches 23. This is because the apparent movement of the Sun seems to stop before it changes direction The word solstice is taken from ‘solstitium’, the latin for ‘sun stands still’. The times when the Sun reaches the limits of its path of declination are known as the solstices. The Vernal Equinox occurs on about the 21 March when the Sun crosses the celestial equator as it moves northwards from 23.5 o South, the southernmost limit of its declination. 5 o North, the northernmost limit of its declination. The Autumnal Equinox occurs on about the 22 September when the Sun crosses the celestial equator as it moves southwards from 23. Because the Sun is on the celestial equator at the equinoxes, its declination is of course 0 o. 12 hours) hence the term equinoxes (equal nights). At the equinoxes, at all places on Earth, the nights and days are of equal duration (i.e. The Sun crosses the celestial equator on two occasions during the course of a year and these occasions are known as the equinoxes. Declination can be summarized as the celestial equivalent of Latitude since it is the angular distance of a celestial body North or South of the Celestial Equator. 5 o South and back again during the course of a year. The declination of the Sun changes from 23.5 o North to 23. The Declination of a celestial body is its angular distance North or South of the Celestial Equator. This can also result in continuous daylight in far northern countries such as Iceland and Norway.Declination. During the summer solstice, the Northern Hemisphere of Earth is tilted towards the Sun, resulting in increased sunlight and warmer temperatures. This situation is reversed at the winter solstice.Īt the summer solstice, the Sun reaches its highest point of the year, while at the winter solstice, the noon Sun is the lowest it will be all year. When it is the summer solstice in the Northern Hemisphere, the areas north of the Arctic circle receive sunlight for a full 24 hours, while areas south of the Antarctic circle have a full day of total darkness. The summer solstice, which occurs around the 21 June in the Northern Hemisphere, is the day of the year with the longest period of daylight while the winter solstice, on or around the 21 December in the Northern Hemisphere, is the day with the shortest period of daylight. These occur twice a year and are referred to as the 'summer solstice' and 'winter solstice'. The equilux is when day and night are equal and occurs a few days before the spring equinox, and a few days after the autumn equinox. The Sun, therefore, appears to rise before its centre at the horizon, giving more daylight than you might expect (12 hours 10 minutes on the equinox). As well as this sunlight is refracted by the Earth's atmosphere. This is because the Sun appears as a disk in the sky, and the top half rises above the horizon before the centre. On the equinox, the length of day and night are only nearly equal. Similarly, the autumn equinox marks the start of autumn as the night becomes longer than the day. The spring equinox marks the beginning of spring and from this day forward the day is longer than the night. During the equinox, day and night will be around the same length which is evident in the word's origin derived from the Latin equi (meaning 'equal') and nox (meaning 'night'). They occur between the summer and winter solstices marking the point the Sun crosses the equator's path and becomes positioned exactly above the equator between the Northern and Southern Hemisphere. The Equinox in the Northern Hemisphere occurs twice a year around 20 March (the spring equinox) and around 22 September (the autumn equinox). The equinox and solstice define the transitions between the seasons of the astronomical calendar and are a key part of the Earth's orbit around the Sun.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |