Reasons for Seasons Exploring the Astronomy of Spring SEASONAL Cycles vs. DAILY Cycles Why do some sun cycle events occur at one single moment for all places on earth, while other sun cycle events occur at different times based on the observer's location? The answer lies in the difference between seasonal sun cycle events and daily sun cycle events. Moments or events in seasonal cycles (e.g., spring and fall equinox, summer and winter solstice) occur everywhere on Earth at the same time. The timing of such seasonal events relates to the Earth's location in space as it revolves around the sun (and not to when something happens locally on Earth). The time of an equinox is an example of this. Specifically, the equinox is defined by the moment when the Sun passes over the plane of Earth's equator. Therefore, an equinox happens at one single moment in space and time, which is not related to something happening locally at your location. It's All About Time Zones: "When" a seasonal cycle event happens depends on where you are because different locations usually use different local time zones. For example, when the equinox occurs, if you're standing at Greenwich and you look at your watch you would see it is 1:00 a.m. on March 21. But if I'm standing in New York when the same equinox occurs, my watch reads 9:00 p.m. on March 20. It's the same event at the same moment, but the time and date are different due to local timekeeping. Moments or events in daily cycles (e.g., sunrise, noon, sunset) occur at different moments in different local places on Earth. The timing of such daily events relates to Earth's spinning (rotating) on its axis. For example, sunrise happens at different times in different locations, because each sunrise relates to when something happens in a specific local location, namely when the sun's light can be seen in that location. Because the Earth rotates each day, the sun hits different areas at different times. Everybody is NOT on the same place on Earth!  Copyright 2001-2007 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form Facebook Pinterest Twitter © 1997 – 2019 Journey North. All rights reserved.