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Do Stars Really Twinkle? And Other Common Scientific Misconceptions

Scientific misconceptions are everywhere, so let's debunk three of the basics. 1.) What causes the seasons? 2.) Is there gravity in space? 3.) Why do stars twinkle?

By
Sabrina Stierwalt, PhD,
Episode #155

Many misconceptions arise because they provide a solution that appears to be more simple than the truth. For example, some people think that the sky is blue because the color reflects off of the blue ocean. Seems pretty straightforward, doesn’t it?

But let’s think about this explanation for a moment. What about areas of sky that don’t cover an ocean, say in the middle of Wyoming? Shouldn’t the sky there be less blue? Well, I’ve driven across the entire state of Wyoming, and I can assure you the sky there is no less blue.

The real reason has to do with preferential scattering of blue light by the Earth’s atmosphere. Although it’s a bit more complicated than a reflected ocean, it’s still a pretty straightforward concept. Let’s look at three more basic scientific misconceptions we are taught early on that don’t stand up to even a little scrutiny.

 

1.) The Earth is not closer to the Sun during the summer

A shocking number of people don’t actually know what causes the seasons, a phenomenon that constantly influences our daily decisions, because they are given the wrong explanation early on. We know that the Sun is hot, and we know that the Earth’s orbit around the Sun is not a perfect circle, so we must be closer to the Sun in our orbit during the summer and further away during the winter.

Anyone who has traveled more than 20 degrees or so both north and south of the equator knows this explanation cannot be true. At a baseball game in the U.S. in July, fans will be drinking icy beverages and eating ice cream out of miniature helmets in order to stay cool. On the same day, at a football game in Santiago, Chile, fans will be bundled up to stave off the cold. That’s because while the northern hemisphere experiences summer, it is winter in the southern hemisphere. Of course, the opposite is also true. Have you ever seen pictures of Santa Claus in Australia?

The distance from the Sun to the Earth in its orbit cannot be causing the seasons since different parts of the Earth experience different seasons at the same time.

Some people are aware that the Earth’s tilt and not its orbit is to blame for the seasons. Here is where this distance misconception refuses to go away. It is true that the 23.5-degree tilt in the Earth as it rotates about its axis is the reason for the seasons, but not in the way that some people think.

Some of us have been taught that the half of the Earth tilted toward the Sun is that much closer and thus hotter than the half of the Earth that is tilted away. This explanation would account for the fact that different hemispheres experience different seasons at the same time.

However, that temperature differential is not significant enough to cause different seasons. The real reason the Earth’s tilt causes the seasons is that during the summer, the portion of the Earth tilted toward the Sun has longer days and more direct sunlight. Thus, there is more opportunity for the Earth to soak up the Sun’s rays. 

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