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The four seasons on earth are present because of how the earth, being tilted on its axis, revolves around the sun, resulting in equinoxes and solstices which mark the beginning of seasons.
Easter falls on the first Sunday after the first full moon of the Spring equinox.
Equi what?
Equinox. In Latin, "Equi" means equal and "nox" means night
What is an equinox?
An equinox is the time during the calendar year when the sun shines directly over the equator, resulting in 12 hours of daylight and 12 hours of darkness in both the northern and southern hemisphere of the earth.
There are two equinoxes in a year.
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- Spring/March Equinox
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- Autumnal/September Equinox
Spring (Vernal/March/Northwards) Equinox
The Spring equinox falls on 20 or 21 March.
According to the Oxford dictionary, "vernal" means spring.
For the northern hemisphere like the United Kingdom, the Spring equinox marks the end of winter and the beginning of spring.
As days continue, the subsolar point - the point on the earth where the sun is perceived to be directly shining perpendicularly or 90° on that point - will "creep" northwards, hence there will be longer days than nights until the Summer/June Solstice.
The sun crosess the equator from the south to the north, hence the Spring Equinox is also called the Northwards Equinox as the solarpoint moves northwards after the spring equinox.
For the southern hemisphere like Australia, the Spring equinox marks the end of their summer and brings in the cold wintery weather. The effects will be the opposite experienced by the northern hemisphere.
As the days continue, countries in the south will experience shorter days and longer nights until the June/Summer Solstice.
During the Spring equinox, everyone on earth will experience equal 12 hours of daylight and 12 hours of darkness.
Autumnal (September/Southward) Equinox
The Autumnal Equinox is another day when both daylight and night hours are equal for everyone on earth and it occurs on 22 or 23 September. The effects are opposite of the Spring Equinox. At this time, the sun crosess the equator from the north towards the south.
Countries in the north will experience the start of autumn/cold weather while those in the south experience the start of spring and warm weather.
After the autumnal equinox, countries in the northern hemisphere, like the UK will slowly experience longer hours of darkness and shorter hours of day until the Winter/December Solstice.
At the same time, countries in the south like Australia will experience shorter hours of darkness and longer hours of daylight.
What is Solstice?
Solstice. In Latin, "sol" means "sun", and "sistere" means "to stand still". During the Summer Solstice, the sun takes a longer time to move across the sky and seems to be "standing still" to the people in the north, hence the name.
The solstice is the instance during the calendar year when the earth is tilted closest to the sun.
There are two solstices in a year.
Summer/June Solstice
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- Falls on either 20 or 21 June
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- Subsolar point shines on the Tropic of Cancer (latitude 23.5° north), the Northmost latitude for the year
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- Northern hemisphere marks the start of warm weather/summer with longest hours of daylight
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- Southern hemisphere marks the start of cold weather/winter with longest hours of darkness
Winter/December Solstice
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- Falls on either 21 or 22 December
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- Subsolar point shines at the Tropic of Capricorn (latitude 23.5° south), the Southmost lattitude for the year
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- Northern hemisphere marks the start of cold weather/winter with longest hours of darkness
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- Southern hemisphere marks the start of warm weather/summer with longest hours of darkness
Summary of Equinoxes, Solstices and Seasons
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- March (Spring) Equinox - when both day and night hours are equal. Sun crosses equator from south to north.
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- From March - June, the north experiences longer day hours while south experiences longer hours of darkness. The subsolar point moves northwards.
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- June (Summer) Solstices - marks the start of summer when the north experiences the longest daylight hours or shortest number of hours of darkness. Countries in the south experience the opposite.
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- From June to September, the north experiences shorter daylight and longer hours of darkness. The subsolar point continues southwards.
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- September (autumnal) equinox - when both day and night hours are equal. The sun crosses the equator from north to south.
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- From September to December, the north experiences shorter daylight hours and longer hours of night and vice versa for countries in the south. The subsolar point continues southwards.
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- December (Winter) Solstice - marks the start of winter when the north experiences the longest hours of darkness and shortest hours of daylight. Countries in the south experience the opposite effect.
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- From December - March, the north experiences longer daylight hours and shorter hours of darkness. The subsolar point moves northwards.. until the Spring Equinox … the cycle continues.
Below you can find the infographics to explain equinoxes and solstices.
But Wait! There is something wrong with the infographic above.
Can you spot the mistake?
Easter, Equinoxes and Solstices for the Next 99 Years!
2000 | 20-Mar | 23-Apr | 21-Jun | 23-Sep | 21-Dec |
2001 | 20-Mar | 15-Apr | 21-Jun | 23-Sep | 22-Dec |
2002 | 21-Mar | 31-Mar | 21-Jun | 23-Sep | 22-Dec |
2003 | 21-Mar | 20-Apr | 22-Jun | 23-Sep | 22-Dec |
2004 | 20-Mar | 11-Apr | 21-Jun | 23-Sep | 21-Dec |
2005 | 20-Mar | 27-Mar | 21-Jun | 23-Sep | 22-Dec |
2006 | 21-Mar | 16-Apr | 21-Jun | 23-Sep | 22-Dec |
2007 | 21-Mar | 8-Apr | 22-Jun | 23-Sep | 22-Dec |
2008 | 20-Mar | 23-Mar | 21-Jun | 22-Sep | 21-Dec |
2009 | 20-Mar | 12-Apr | 21-Jun | 23-Sep | 22-Dec |
2010 | 21-Mar | 4-Apr | 21-Jun | 23-Sep | 22-Dec |
2011 | 21-Mar | 24-Apr | 22-Jun | 23-Sep | 22-Dec |
2012 | 20-Mar | 8-Apr | 21-Jun | 22-Sep | 21-Dec |
2013 | 20-Mar | 31-Mar | 21-Jun | 23-Sep | 22-Dec |
2014 | 21-Mar | 20-Apr | 21-Jun | 23-Sep | 22-Dec |
2015 | 21-Mar | 5-Apr | 22-Jun | 23-Sep | 22-Dec |
2016 | 20-Mar | 27-Mar | 21-Jun | 22-Sep | 21-Dec |
2017 | 20-Mar | 16-Apr | 21-Jun | 23-Sep | 22-Dec |
2018 | 21-Mar | 1-Apr | 21-Jun | 23-Sep | 22-Dec |
2019 | 21-Mar | 21-Apr | 21-Jun | 23-Sep | 22-Dec |
2020 | 20-Mar | 12-Apr | 21-Jun | 22-Sep | 21-Dec |
2021 | 20-Mar | 4-Apr | 21-Jun | 23-Sep | 21-Dec |
2022 | 20-Mar | 17-Apr | 21-Jun | 23-Sep | 22-Dec |
2023 | 21-Mar | 9-Apr | 21-Jun | 23-Sep | 22-Dec |
2024 | 20-Mar | 31-Mar | 21-Jun | 22-Sep | 21-Dec |
2025 | 20-Mar | 20-Apr | 21-Jun | 23-Sep | 21-Dec |
2026 | 20-Mar | 5-Apr | 21-Jun | 23-Sep | 22-Dec |
2027 | 21-Mar | 28-Mar | 21-Jun | 23-Sep | 22-Dec |
2028 | 20-Mar | 16-Apr | 21-Jun | 22-Sep | 21-Dec |
2029 | 20-Mar | 1-Apr | 21-Jun | 23-Sep | 21-Dec |
2030 | 20-Mar | 21-Apr | 21-Jun | 23-Sep | 22-Dec |
2031 | 21-Mar | 13-Apr | 21-Jun | 23-Sep | 22-Dec |
2032 | 20-Mar | 28-Mar | 21-Jun | 22-Sep | 21-Dec |
2033 | 20-Mar | 17-Apr | 21-Jun | 23-Sep | 21-Dec |
2034 | 20-Mar | 9-Apr | 21-Jun | 23-Sep | 22-Dec |
2035 | 21-Mar | 25-Mar | 21-Jun | 23-Sep | 22-Dec |
2036 | 20-Mar | 13-Apr | 21-Jun | 22-Sep | 21-Dec |
2037 | 20-Mar | 5-Apr | 21-Jun | 23-Sep | 21-Dec |
2038 | 20-Mar | 25-Apr | 21-Jun | 23-Sep | 22-Dec |
2039 | 21-Mar | 10-Apr | 21-Jun | 23-Sep | 22-Dec |
2040 | 20-Mar | 1-Apr | 21-Jun | 22-Sep | 21-Dec |
2041 | 20-Mar | 21-Apr | 21-Jun | 22-Sep | 21-Dec |
2042 | 20-Mar | 6-Apr | 21-Jun | 23-Sep | 22-Dec |
2043 | 21-Mar | 29-Mar | 21-Jun | 23-Sep | 22-Dec |
2044 | 20-Mar | 17-Apr | 21-Jun | 22-Sep | 21-Dec |
2045 | 20-Mar | 9-Apr | 21-Jun | 22-Sep | 21-Dec |
2046 | 20-Mar | 25-Mar | 21-Jun | 23-Sep | 22-Dec |
2047 | 21-Mar | 14-Apr | 21-Jun | 23-Sep | 22-Dec |
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2049 | 20-Mar | 18-Apr | 21-Jun | 22-Sep | 21-Dec |
2050 | 20-Mar | 10-Apr | 21-Jun | 23-Sep | 22-Dec |
2051 | 20-Mar | 2-Apr | 21-Jun | 23-Sep | 22-Dec |
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2053 | 20-Mar | 6-Apr | 21-Jun | 22-Sep | 21-Dec |
2054 | 20-Mar | 29-Mar | 21-Jun | 23-Sep | 22-Dec |
2055 | 20-Mar | 18-Apr | 21-Jun | 23-Sep | 22-Dec |
2056 | 20-Mar | 2-Apr | 20-Jun | 22-Sep | 21-Dec |
2057 | 20-Mar | 22-Apr | 21-Jun | 22-Sep | 21-Dec |
2058 | 20-Mar | 14-Apr | 21-Jun | 23-Sep | 21-Dec |
2059 | 20-Mar | 30-Mar | 21-Jun | 23-Sep | 22-Dec |
2060 | 20-Mar | 18-Apr | 20-Jun | 22-Sep | 21-Dec |
2061 | 20-Mar | 10-Apr | 21-Jun | 22-Sep | 21-Dec |
2062 | 20-Mar | 26-Mar | 21-Jun | 23-Sep | 21-Dec |
2063 | 20-Mar | 15-Apr | 21-Jun | 23-Sep | 22-Dec |
2064 | 20-Mar | 6-Apr | 20-Jun | 22-Sep | 21-Dec |
2065 | 20-Mar | 29-Mar | 21-Jun | 22-Sep | 21-Dec |
2066 | 20-Mar | 11-Apr | 21-Jun | 23-Sep | 21-Dec |
2067 | 20-Mar | 3-Apr | 21-Jun | 23-Sep | 22-Dec |
2068 | 20-Mar | 22-Apr | 20-Jun | 22-Sep | 21-Dec |
2069 | 20-Mar | 14-Apr | 21-Jun | 22-Sep | 21-Dec |
2070 | 20-Mar | 30-Mar | 21-Jun | 22-Sep | 21-Dec |
2071 | 20-Mar | 19-Apr | 21-Jun | 23-Sep | 22-Dec |
2072 | 20-Mar | 10-Apr | 20-Jun | 22-Sep | 21-Dec |
2073 | 20-Mar | 26-Mar | 21-Jun | 22-Sep | 21-Dec |
2074 | 20-Mar | 15-Apr | 21-Jun | 22-Sep | 21-Dec |
2075 | 20-Mar | 7-Apr | 21-Jun | 23-Sep | 22-Dec |
2076 | 20-Mar | 19-Apr | 20-Jun | 22-Sep | 21-Dec |
2077 | 20-Mar | 11-Apr | 21-Jun | 22-Sep | 21-Dec |
2078 | 20-Mar | 3-Apr | 21-Jun | 22-Sep | 21-Dec |
2079 | 20-Mar | 23-Apr | 21-Jun | 23-Sep | 22-Dec |
2080 | 20-Mar | 7-Apr | 20-Jun | 22-Sep | 21-Dec |
2081 | 20-Mar | 30-Mar | 20-Jun | 22-Sep | 21-Dec |
2082 | 20-Mar | 19-Apr | 21-Jun | 22-Sep | 21-Dec |
2083 | 20-Mar | 4-Apr | 21-Jun | 23-Sep | 22-Dec |
2084 | 20-Mar | 26-Mar | 20-Jun | 22-Sep | 21-Dec |
2085 | 20-Mar | 15-Apr | 20-Jun | 22-Sep | 21-Dec |
2086 | 20-Mar | 31-Mar | 21-Jun | 22-Sep | 21-Dec |
2087 | 20-Mar | 20-Apr | 21-Jun | 23-Sep | 22-Dec |
2088 | 19-Mar | 11-Apr | 20-Jun | 22-Sep | 21-Dec |
2089 | 20-Mar | 3-Apr | 20-Jun | 22-Sep | 21-Dec |
2090 | 20-Mar | 16-Apr | 21-Jun | 22-Sep | 21-Dec |
2091 | 20-Mar | 8-Apr | 21-Jun | 23-Sep | 21-Dec |
2092 | 19-Mar | 30-Mar | 20-Jun | 22-Sep | 21-Dec |
2093 | 20-Mar | 12-Apr | 20-Jun | 22-Sep | 21-Dec |
2094 | 20-Mar | 4-Apr | 21-Jun | 22-Sep | 21-Dec |
2095 | 20-Mar | 24-Apr | 21-Jun | 23-Sep | 21-Dec |
2096 | 19-Mar | 15-Apr | 20-Jun | 22-Sep | 21-Dec |
2097 | 20-Mar | 31-Mar | 20-Jun | 22-Sep | 21-Dec |
2098 | 20-Mar | 20-Apr | 21-Jun | 22-Sep | 21-Dec |
2099 | 20-Mar | 12-Apr | 21-Jun | 23-Sep | 21-Dec |