Explanation: The axial tilt causes the days to be longer than the nights in Summer and shorter in Winter. What solar system is Pluto in? Which planet in our solar system is most earth like? What is the closest planet to the sun? Why are the planets closest to the sun rocky?
Now picture a stick going right through the center of the earth. If the earth weren't tilted, it would rotate like that as it revolved around the sun, and we wouldn't have seasons—only areas that were colder near the poles and warmer near the Equator. But the earth is tilted, and that's why the seasons happen. When the Northern Hemisphere is pointed toward the sun, it gets more hours of sunlight.
Temperatures rise, and you get summer in New York, while it's darker and cooler "down under" in Sydney. Six months later, the reverse is true, and it's the Southern Hemisphere that experiences summer. The degree tilt also explains why changes in daylight during the seasons are very dramatic near the poles which are flooded with sunlight all day long in summer and get virtually no light in mid-winter but barely perceptible near the equator where the sun shines more or less equally throughout the year.
Getting back to why the axis exists, it's mainly the result of the rough-and-tumble environment of the early solar system. Scientists believe that the sun and the eight planets formed by chunks of rock and debris that self-accumulated through gravity. In other words, objects collided and clumped together, which increased their gravitational pull, which in turn drew more objects in, which made the object even more gravitationally powerful, and so on until the solar system looks like a sun and eight fairly neat planets with not much stray junk flying around.
Of course, occasionally these forming objects happen to attract something that's big enough to knock it off-kilter. It wobbles up and down by a couple of degrees every 41, years or so at the moment the tilt is slowly decreasing , and the strength of the seasons the earth experiences changes with it. When the tilt is greater, summers are warmer and winters are colder, and when the tilt is smaller there's less of a difference in the seasons.
These repeating cycles in the strength of the seasons probably play an important role in forcing the huge climate shifts of the glacial cycles that the earth has experienced over the last million years - and that's all with changes of just 2 or 3 degrees in the tilt. For fun, I set up a relatively simple model to simulate what the climate on an earth with a 0 degree tilt might be like. There are a few details that make this more of a toy than a serious scientific study, but we can still use it to illustrate some of the things that could happen in a 0 degree world.
To start with, of course, the seasons disappear: although the weather is still different from day to day, February is much the same as June and October. However, if you guessed that the earth's climate in a 0 degree tilt world would permanently be stuck halfway between our usual summer and winter, you'd be wrong! The top panel shows a very simple way to characterise the climate of our 23 degree world in this kind of scheme.
Greens show areas predominantly suitable for types of forest, browns are drier areas and grasslands, with grey for tundra, yellow for deserts and barren areas and ice caps in blue.
There's a lot of fertile vegetation in this view of our world, with some desert in the hotter, drier areas and tundra and polar ice right up in the north. The bottom panel shows what our toy simulation of a 0 degree world looks like. This climate is much less suited to our usual types of vegetation, with much larger barren desert areas, and a huge expansion of polar ice over Asia and North America.
The area suitable for vegetation at in the northern hemisphere shrinks dramatically, and northern Europe swaps its forests for tundra. The average temperature here in Britain sinks to a cool 7 degree C all year round, only varying by a couple of degrees warmer or cooler at most. Not everything would change for us, though - we'd still get about as much rain every year in a 0 degree tilt climate as we do now.
So, the earth's 23 degree tilt doesn't just give us the variations of the seasons and all the wonderful things we'll be seeing from this series - it's really important for setting the basic foundations of the environment we take for granted in our part of the world.
Basically, we would not have any seasons. Earth would be warm at the equator and cold at the poles. The poles would still experience the most impact because the sun would always be low on the horizon.
Because Venus has a tiny tilt, the diversity of seasons plays a small role. So it is not all about the distance from the sun, but the tilt. Brooke Silverang ,.
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