The Eclipse Seasons

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There can be no doubt that solar and lunar eclipses are some of the most fascinating sights for the “naked” eye. (And I say “naked” under the assumption that you know never to look directly at the sun without approved protection!)

Unless it’s during totality. Then you can take those glasses off.

But what I mean is, solar and lunar eclipses don’t require telescopes or binoculars to be seen. You don’t need to use any special equipment. You just need your eyes, and in the case of a solar eclipse, some form of protection—like solar glasses.

You may have noticed that when a solar eclipse comes up—or even a lunar eclipse—it’s all the rage. Suddenly, the media is swamped with safety warnings and calendar countdowns to the big event.

The United States just about lost its mind over the solar eclipse of August 21, 2017. And I have a feeling the next total solar eclipse to pass over the US, in seven years, will be just as dramatic.

But you might also be wondering…how do we know when these incredible sights are going to happen? Continue reading

Milankovitch and Climate

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The Yugoslavian meteorologist Milutin Milankovitch is known for coming up with the idea of orbital forcing, also known as Milankovitch cycles. Orbital forcing is a fancy term for certain changes in Earth’s orbit, which are precession, obliquity, and eccentricity.

I’ve written about all three of these before, but here’s a brief overview:

Precession is the motion of Earth’s axis like a spinning top. Imagine the Earth’s day-by-day rotating motion as that of a top. What do tops also do? They wobble.

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Although I’ve written about obliquity, I haven’t used the term before. It’s a fancy word for how the tilt of the Earth’s axis doesn’t stay at the same angle. It changes a bit over a very long period of time, ranging between 22° and 24°.

Eccentricity refers to the changing shape of Earth’s orbit. You might know that it’s not a perfect circle—it’s an ellipse, which I’ll talk about in more depth later. What you might not know is that how elliptical it is—that is, how far it is from being a perfect circle—also changes a bit over time.

These motions are all very well established in science today. We know that they each have an effect on Earth’s climate, and together they cause the ice ages. But Milutin Milankovitch, the scientist who first came up with the idea, had a lot going against him. Continue reading

Orbit and Climate

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You have probably all heard of ice ages.

v1.bjsxMTYxNDc0O2o7MTc0NzM7MTIwMDsyNTAwOzE1MDA.jpgAnd no, I don’t mean the Ice Age movies…

Although, Ice Age is actually a pretty good example of what happens during a real-life ice age. I haven’t seen enough of the movies to really talk about how accurate they are, but I know there’s a lot of ice.

And a lot of breaking of ice.

These movies take place during a time when much of the northern and southern regions of the Earth were covered in glaciers. The world looked a lot like the satellite image up above. Whether mammoths and smilodons (sabre-toothed cats) actually lived then is another question entirely.

For the record, dinosaurs were definitely not still alive back then. Even deep under the ice. The quote from the third movie basically sums it up:

“I thought those guys were extinct!”

“Then that is one angry fossil…”

Yeah, they were extinct. But fiction can do whatever it wants.

But why do ice ages happen…and why isn’t the world covered in glaciers now? Continue reading

Precession

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We have a bit of a shorter post today—I thought precession warranted its own post, before I go on to talking about the ecliptic.

Precession is refers to the way Earth wobbles around on its axis, a bit like a top. This motion is caused by the sun and moon’s gravity tugging on the planet, and is key to understanding how many ancient cultures viewed the sky.

So what is precession, exactly? Continue reading