Looking Up: Tilt A Whirld

Sep 23, 2019

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Happy Autumnal Equinox from Looking Up!

Today marks the September Equinox. Most folks have heard of the two equinox events we have every year, the beginning of spring, with the Spring Equinox in March, and the Fall Equinox that falls in September. And today’s the big day. So, what does that actually mean?

The Earth is tilted on its axis by about 23 degrees, likely the result of getting smacked by an object or objects way back when the Solar System was forming. Some planets have almost no tilt, like Mercury, while others have much larger tilts. Uranus, for example, is tipped 98 degrees, meaning that it seems to roll through space on its side. Our comfy 23-degree tilt is what gives us seasons, and the equinoxes mark the day when, the Sun seems to shine directly above the equator and the day is pretty much as long as the night, at about 12 hours each. This year, the precise moment of the equinox fell on today at 1:50 am, so you likely were asleep. No biggie, because other than day and night being about equal, there is nothing to see. But you can make a mental note that the periods of daylight are getting shorter, while the nights grow longer. But don’t worry, next March, we’ll reverse the process and the Spring equinox will mark the beginning of longer days.

If you’d like to take a closer look at the Sun, or any of the other wonderful and amazing things in the sky, please visit csastro.org for a link to information on our monthly meetings and our free public star parties.