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During the aphelion, our planet receives 7% less sunlight than in January, but changes in the planet's orbit do not cause our seasons.
On Friday, the Earth will swing to the farthest point of its orbit. You, me and everyone on the planet will be three million miles farther from the sun than when we are closest to it.
The change occurs because the orbit of our planet is not perfectly circular. Instead, it is crushed in an ellipse with the sun shifted from the center – an effect that orbits around its farthest point every July and its deepest point, or perihelion, every January (the exact dates vary slightly from year to year).
So while record temperatures and forest fires are raging in the Northern Hemisphere, you might think that the sun is close to reality, remember that it's just the opposite. In fact, the extra distance reduces the amount of light received by 7% compared to January.
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But do not expect any relief from the summer. The seasons on Earth are the product of changes in the amount of direct sunlight when the planet sinks to the sun and not to its orbit. It would take a much larger movement, so that the amount of light received decreases considerably, in order to notice the difference.
To consider what life would be on a planet in these orbital circumstances, just look at it as far as Mars, whose elliptical orbit varies the amount of light received up to 31 percent at during the year of the planet.
"I find it amusing that the common misconception about Earth's seasons is true if you're on Mars," said David Grinspoon, astrobiologist at the Planetary Science Institute. "Schoolchildren on Mars will have to be taught differently."
Much like the Earth, Mars is heading towards the icy cold solar system at the peak of the northern hemisphere's summer and winter. winter of the Southern Hemisphere. But because this swing is so much more spectacular, diving into the sunlight creates a sweeter summer from the north and an icy winter from the south. Later, Mars snuggles up near the sun, leading to a milder northern winter and a simmering southern summer.
"It's like slowly toasting your marshmallow a safe distance above the campfire, then dive into the vicinity for the arctic char," said Tanya Harrison, a planet scientist of the United States. Arizona State University.
In short, the dramatic orbit of the planet moderates the sway between seasons to the north but exaggerates the south.
The effect is so strong that it can even be seen through a backyard telescope. The polar caps of the red planet, for example, grow in winter and shrink in summer. But as the austral winter is much more extreme than the northern winter, the southern polar ice caps grow more than twice as much as their northern counterparts.
On the other hand, this hot southern summer gives rise to winds so strong that they tear the dust off the Martian soil and into the atmosphere. This can trigger dust storms that grow so large that they envelop the entire planet, much like the one that is currently threatening NASA's Opportunity Rover.
Moreover, not only does such a crushed orbit cause asymmetry in the strength of the seasons, but also in their length. When a planet is at the edge of the farthest point of its orbit, it slows down considerably. Then he will gain speed as he begins to retreat to the sun. This means that even though the summers of southern Mars are intense, they are also about 30 days shorter than the northern summers.
Still, the change of seasons on Mars is not as dramatic as it could be.
"Martians experience their change in orbital distance much more distinctly than Earthmen," said Richard Binzel, an astronomer at the Massachusetts Institute of Technology. "But the Pluto guys have it even worse."
The orbit of the dwarf planet is even flatter than the orbit of Mars, varying sunlight by 64%. That said, during orbit around 250 years of Pluto around the sun, its closest approach occurs in the spring and fall, when sunlight has a less pronounced effect than during the summer. 39, summer of one hemisphere. But that was not always the case. Due to fluctuations between planets throughout the ages of our solar system, the closest approach to Pluto changes steadily over the seasons.
A little less than a million years ago, Pluto huddled closer to the sun. Both effects conspired to create a "super season" where the temperatures were so hot that liquids of methane and nitrogen could have flowed through its icy surface. "It's a very hot day on Pluto," said Dr. Binzel. Signs of these flows were detected by NASA's New Horizons spacecraft when it surveyed the planet in 2015.
And while the planet has cooled over the last 900,000 years, it will reach 900,000 additional years. The spikes from the hemisphere to the sun at the exact point where it oscillates closest.
The orbit of the Earth will also change someday. While the closest approach to our planet to the sun is currently taking place during the northern winter, it has slowly changed over time. In about 10,000 years, its closest approach will occur six months later during the northeastern summer.
But given the Earth's relatively circular orbit, it will never have super seasons like those of Pluto or the extreme asymmetric seasons of Mars. Instead, our planet will remain relatively stable – a feature that could have given birth to life.
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