#Solstice and equinox worksheets install#

#Solstice and equinox worksheets install#

(You may want to install an ad blocker before viewing.Chapter 3 Rotation and Revolution Class 9 - Total Geography Morning Star Follow the “Show Me More” link at the bottom to follow the discussion through equinoxes and to the end of More About Rotation IV. More complicated explanations with diagrams. The Sun in the sky during the Spring and Fall Equinoxīrief explanation with helpful illustration.Īn explanation in more story-like form from PBS. The Seasons, the Equinox, and the Solstice Have your child tell you everything he can about equinoxes.Have your child tell you why we have seasons.Do the orange and lamp experiment explained above.While every leap year helps the equinox to catch up with March 21st, it takes a non-leap-year century year to correct the dates. Because the calendar is not exact, and has corrective leap years every four years except on century years, the equinox falls earlier and earlier. This shift in dates is due to the fact that the equinox only happens when the sun crosses the celestial equator, the imaginary line above the earth’s equator dividing the sky in two. The date of the first day of spring varies from calendar to calendar in any given year - some using March 21st, the day Pope Gregory the XIII used, others using March 20th, or even March 19th depending on the day when the true equinox falls. The true spring equinox doesn’t necessarily arrive on the “first day of spring,” however. In this new calendar, Pope Gregory the XIII set the date of the spring equinox to March 21st.

To accomplish the elimination of the drift, he removed three days every four centuries by decreeing that leap years on any year ending with two zeros would be canceled unless the first two digits alone were divisible by four. In the 1500s Pope Gregory the XIII, created the Gregorian calendar to remedy the problem. The result was a drift so large that in the 1500s (according to the Julian calendar) the true equinox was occurring around March 11. However, Julius Caesar’s calendar drifted, as it was too long relative to the true length of the year. The date for the spring equinox was originally set at March 25th by Julius Caesar when creating his calendar. The equinox will occur when the sun has reached the same plane as the earth’s equator, as the equator divides the earth in two, causing both hemispheres to be illuminated evenly.

When the earth orbits the sun, the quantity of both the northern and southern hemispheres that is being illuminated changes. As an example of what this means, take an orange, tilt it, and orbit it around a lamp while keeping the tilt always pointing in the same direction regardless of where the orange is in relation to the lamp. This tilt is always in the same place regardless of where the earth is relative to the sun. Why does the sun cover both hemispheres evenly only twice a year? The earth is tilted 23.26 degrees on its axis. When Does an Equinox Occur?Īn equinox occurs when the earth is such that the sun covers both the northern and southern hemispheres evenly, causing spring in the one and fall in the other. There are two times when this occurs in a year - the spring equinox on or around the 20th of March, and the fall equinox on or around the 22nd of September.

Named for the Latin aequus (equal) and nox (night), during an equinox day and night are roughly the same length - although they actually never are exactly the same length. The equinox is the time of year when the sun is in the same plane as the earth’s equator.