Thanks to Skillshare for supporting  this episode of SciShow Space.

The first 1,000 people to click  the link in the description can get a free trial of  Skillshare’s Premium Membership. [♪ INTRO]. There is perhaps no bigger issue facing humanity in the 21st century than the climate crisis.

Scientists now know with certainty that human industrial activity is the  primary driver of our warming planet. To fight back, we’re going to have to take  big actions, like eliminating the use of fossil fuels, stopping deforestation, and  shifting to more sustainable agriculture. Or, you know, we could just move the planet,  just like, a little farther from the Sun.

No big deal. This idea has been floated,  I think disingenuously, in the vaunted halls of the US Congress. And we’re not going to do it,  but I am curious: would it work?

And would it be possible? To answer those questions, we need to understand how Earth’s orbit affects its climate. The idea that changes in our planet’s orbit  are connected to changes in the climate is something that scientists have  been studying for more than a century.

Our modern understanding of their  connection dates back to 1911, when Serbian mathematician Milutin  Milankovitch began comparing the timing of past ice ages to the  position and orientation of the Earth. He identified cyclical patterns  in Earth’s orbital parameters that spanned thousands, or even  tens of thousands, of years… what scientists today call  the Milankovitch cycles. Three factors in particular have  long-term effects on Earth’s climate.

The first is changes to our planet’s  eccentricity, or how elongated its orbit is. If the planet’s orbit were a  perfect circle, Earth would receive the same amount of sunlight all year long. But, instead, that orbit is a little bit squished, meaning sometimes we’re closer to the  Sun, and sometimes we’re farther away.

Right now, the difference between that minimum and maximum sunlight is a mere 6%. But, due to the gravitational pull of  Jupiter and Saturn, sometimes our orbit stretches out enough for the difference between minimum and maximum sunlight to reach 23%. And this isn’t exactly a year-to-year variation.

The cycle from most-circular to least-circular takes about a hundred thousand years. The second factor is Earth’s obliquity,  or how tilted its axis of rotation is. Our planet’s tilt creates the seasons,  not its distance from the Sun.

The more tilted we are, the  more extreme the differences become between the seasons. That tilt varies between 22.1 and 24.5  degrees, in a cycle that lasts 41,000 years. And finally, last we have our axial precession, or how wobbly the planet is as it rotates.

This varies over 26,000  years, and is responsible for how balanced the seasons are in the  Northern and Southern Hemispheres. Thanks to precession, summers are hotter and winters are colder in the Southern Hemisphere. But in 13,000 years, it’ll be the north that  experiences the more extreme conditions.

Taken together, the Milankovitch cycles  help explain why Earth’s history is marked by a seemingly-endless pattern of frigid  ice ages and temperate interludes. But what they cannot explain is our  current period of global warming. Remember, all of these cycles take  tens of thousands of years to complete.

A lot of the effects of climate change  are being felt over a mere century or so, which is a blip on the Milankovitch timeline. What has changed in that time  is the scale of human activity, and the amount of heat-trapping pollution  we have released into the atmosphere. And, that brings us back to this fantasy of moving the Earth just a teensy  bit farther from the Sun.

Which, again, is not going to happen,  but the Milankovitch cycles tell us that our orbit does affect the climate, so it  seems like it could theoretically work. As you get further from the sun, the  intensity of sunlight drops off rapidly, as a function of the distance squared, in fact. So a relatively small change could  have a meaningfully large effect.

Now scientists aren’t sure how much  Earth will warm in the 21st century, but the best estimates put that number between one-and-a-half and  four-and-a-half degrees Celsius. Now to fight back against  the middle of those estimates and cool the Earth about 3 degrees  Celsius, we would “only” need to move our planet about 2%, farther  away from the sun than it is today, which is a mere 3 million kilometers. And accomplishing that is a  lot easier to say than do.

Astronomers have thought  up a few possible methods, but none of them are what you would call good. We could detonate a pile of  strategically-located nuclear bombs, basically vaporizing parts of the Earth’s surface to push us in the opposite direction. That would take five hundred years if we could drop one bomb every second, day and night.

Now in that situation Earth  might end up in the right place, but there probably wouldn’t be  much life left for it to matter. Also, that is so many bombs. Instead, we could shoot a laser at the Moon with the power of every wind turbine  currently operating in the US.

That would push the Moon’s  orbit out from the Earth, which would drag the Earth farther out with it. This would totally work if you  have 300 trillion years to wait. So we need another option.

How about snagging asteroids  and slingshotting them around the Earth for a gravitational boost? Unfortunately, even if we did this with  every asteroid in the asteroid belt, it would only get us about a quarter  of the way to where we need to be. And also, then there would just be no more  asteroid belt, which isn’t very much fun.

And if one of those bad boys hit the Earth  by accident, could be game over for us. So we are left with one option that makes sense, and that is to leave our planet’s orbit alone. Obviously the negative effects of any of  these other ideas, and the amount of effort, are just mind-meltingly more than sorting out our greenhouse gas addiction here at home.

Sure, changing the way we live,  work, and play will be a big deal, but it’s a good bit better than five hundred years of unending nuclear explosions. At least that’s how I feel. Thanks for watching this episode of SciShow Space, which was supported by Skillshare.

Skillshare is an online learning community  that offers membership with meaning. With so much to explore, real  projects to create, and the support of fellow-creatives, Skillshare empowers  you to accomplish real growth. If the idea of our changing climate has  you feeling a little bit anxious, you might enjoy The Ultimate Self-Care Playbook  with none other than Johnathan Van Ness.

But there’s also plenty of new  courses launching all the time, ad-free and curated especially for learning. If you’re interested, the first 1,000 people  to click on the link in the description can get a one month free trial of Premium Membership. So thank you for your support. [♪ OUTRO].