Night Vision: Reasons for the Seasons

Amy Oliver

Punxsutawney Phil is a liar (maybe) and whether you think the groundhog lied to you this year or not, the Spring Equinox is coming, and that means two things: it’s time for a reminder about how the seasons work, and it’s a time to remember that it’s not what we think.

As the host of this week’s edition, “Reasons for the Seasons,” it’s important to me to clear the air and clarify any misconceptions right here, right now, so we can move on and enjoy the more glorious parts of Spring, like temperate climates and green things. But first things first: I have to say that this concept has always been a difficult one for me because it just doesn’t make sense in the way that we normally think! But that’s what Night Vision is all about: making sense of all the topics out there that have to do with space science. When I first presented this topic last Spring, I thought I would never be able to explain it. But explain it I did, and I’m back this time with a much better personal understanding of and passion for the science that makes our seasons happen.

According to NASA’s Space Place article, What Causes the Seasons, “Many people believe that Earth is closer to the Sun in the summer and that is why it is hotter. And likewise, they think Earth is farthest from the Sun in the winter.” But the fact of the matter is that it’s completely the opposite. NASA points out that for those of us living in the Northern Hemisphere, in places like Utah, Earth is actually closer to the Sun during the winter months and further away from the Sun during the summer months. But what about Earth’s spin; what does that have to do with the seasons? Well, it turns out, not a whole lot. The spin of the Earth determines night and day, not really the seasons.

So why do we have seasons at all? Well, according to Earth Sky, it’s because Earth’s axis doesn’t stand up straight. The orbit of Earth isn’t a perfect circle; it’s oblong and that’s why we are sometimes closer to the Sun and sometimes further away. So what does it mean to have an Equinox? It means that “the tilt of the Earth’s axis and Earth’s orbit around the Sun combine in such a way that the axis is inclined neither away from nor toward the Sun.” Basically that means that both the Northern and Southern hemispheres of Earth are getting the same amount of Sun. This happens twice a year–Spring and Fall–and these times of year are more temperate than Summer and Winter, where the tilt of the axis positions us either towards the Sun’s warm rays or away from them.

Check out this image from 2011 by Geosync, showing the way the Sun’s light touches Earth during the different seasons of the year.

equinox-solstice-via-Geosync

So what does all this mean to you?

Our notions are false. Let go of your preconception of what it means for the seasons to happen; reality is that the closer we get to Summer the further we get from the Sun.

Spring is here. The Spring Equinox is coming on March 20th, 2017, and that means your world is about to get more temperate, in temperature anyway. We can’t do much about the rest of it! And considering the past few months, I know how disappointing that must be.

Earth keeps moving. Don’t forget that every day Earth keeps moving and that means that we’re going to get further away from the Sun, hotter on the surface, and closer to the next Equinox and to Winter with every spin of our rock. If you’re aching to learn more about the seasons or you have burning questions to ask about the tilt of Earth on its axis or why the spin of Earth doesn’t have anything to do with the seasons, don’t miss this week’s edition of Night Vision: Reasons for the Seasons.

Night Vision: Reasons for the Seasons is presented by Amy C. Oliver on Thursday evening, March 16th, and Saturday evening, March 18th, in the Hansen Dome Theatre at 6:45pm. Tickets available online or at the Clark Planetarium ticket desk. Free for members.

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