9/17/2023 0 Comments 2021 fall equinoxBut during the equinoxes, with the east-west grid layout of the city, we have the perfect opportunity to see "Chicagohenge. In the winter, it is a little farther to the north and during summer it is a little farther to the south. Throughout the year, the sun sets and rises at different points on the horizon. The sun is framed perfectly between the buildings on each side of the road. The spring equinox arrives Monday, March 20, 2023. September's equinox has arrived today, marking the beginning of astronomical autumn in the Northern Hemisphere, where the nights will get longer than the days until the spring equinox in March 2022. 22.ĬHICAGO (WLS) - What is Chicagohenge? It happens twice a year when we are treated to a special alignment of the sun and our beautiful city buildings.įor a week or so around the Spring and Fall Equinox (around March 21 and September 21 most years), you can see the sunrise and sunset looking down the east-west streets of downtown Chicago. Other factors influencing the timing of the equinoxes and solstices include variations in the length of a tropical year and in the orbital and daily rotational motion of the Earth, such as the “wobble” in the Earth's axis (precession).Chicagohenge 2021 will treat us to a special alignment of the sunrise and sunset with Chicago's skyscrapers around the Fall Equinox on Sept. When this happens, the equinox and solstice dates shift back to the earlier date again. To realign the calendar with the tropical year, a leap day is introduced (nearly) every four years. Eventually, the accumulated lag becomes so large that it falls on the following date. This means that the timing of the equinoxes and solstices slowly drifts apart from the Gregorian calendar, and the solstice happens about 6 hours later each year. However, our planet takes about 365.242199 days to orbit the Sun. Heres when fall 2023 starts and ends this year. Today's Gregorian calendar has 365 days in a common year and 366 days in a leap year. The autumn equinox determines the first day of fall, usually September 22 or 23 in the Northern Hemisphere. The date of the equinoxes and solstices varies because a year in our calendar does not exactly match the length of the tropical year-the time it takes the Earth to complete an orbit around the Sun. The equinox in September is the start of fall in the Northern Hemisphere and the beginning of spring south of the equator.Įquinox and solstice dates-years 1-2149 Why Does the Date Vary? The March and September equinoxes mark the beginning of the spring and autumn seasons on Earth, according to one definition. Mabon is the mid-harvest festival, and it is when we take a few moments to honor the changing seasons and celebrate the second harvest. The fields are nearly empty because the crops have been plucked and stored for the coming winter. In reality, equinox days don’t have exactly 12 hours of daylight and 12 hours of dark.Įquilux: when day and night are (actually) equalĪstronomical terms & definitions The Equinoxes and the Seasons Updated on JIt is the time of the autumn equinox, and the harvest is winding down. However, this is literal translation not entirely true. This is the reason it’s called an “equinox,” derived from Latin, meaning “equal night.” In other words, night and day are, in principle, the same length all over the world. On the days of the equinoxes, the Earth’s axis is perpendicular to the Sun’s rays, meaning that all regions on Earth receive about the same number of hours of sunlight. As the Earth travels toward the opposite side of its orbit, which it reaches in December, the Southern Hemisphere gradually receives more sunlight, and the subsolar point travels south.Įarth is tilted as it orbits the Sun, which is why equinoxes and solstices happen. In June, the Northern Hemisphere is tilted toward the Sun, and the subsolar point is north of the equator. The subsolar point moves north and south during the year because the Earth’s axis is tilted at an angle of about 23.4° in relation to the ecliptic, an imaginary plane created by Earth’s path around the Sun. The December solstice marks the southernmost point of its journey. Having reached its northernmost point at the June solstice, it starts moving southward until it crosses the equator on the day of the September equinox.
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