The Fantastic Formation of the Solar System!
July 14th, 2021
Welcome to Megan’s Climate Corner!
The Universe is ancient, much older than human beings can really fathom, at a whopping 12-13 billion years! We have determined this age range from examining the cosmic microwave background (the “after-glow” of the Big Bang, when electrons began forming the first atoms), estimating the age of different stars in globular clusters (groupings of a million or more stars, all of which are different densities and burn at different rates), and by observing the current rate of expansion to extrapolate back in time. You can read more about the age of the universe here: https://starchild.gsfc.nasa.gov/docs/StarChild/questions/question28.html. Today, we concern ourselves only with our own solar system: our yellow medium star, the sun, and the eight planets that orbit it.
Gravity is a measurable, calculatable force (proportional to mass) that pulls objects toward one another. It’s what pulls everything toward the center of the Earth, and binds all objects in space to a regular orbit. We orbit our sun. Our Milky Way galaxy orbits itself, pinwheel arms spiraling away from its center, where a supermassive black hole resides.
Our Solar System formed about 4.5 billion years ago from a thick cloud of gas and dust, which condensed rapidly (perhaps from the shockwave of a supernova) and became a swirling spinning disk called a solar nebula, thus creating the sun, the rocky inner planets (Mercury, Venus, Earth, and Mars), and the gaseous outer planets (Jupiter, Saturn, Uranus, Neptune). Read more here: https://solarsystem.nasa.gov/solar-system/our-solar-system/in-depth/
Under the force of this spinning and the force of gravity, the elements of Earth separated out to form distinct layers: the light, silicate minerals floated to the outer shell to form the crust while the heavy, super dense iron and nickel condensed in the center of the planet, into our hot, slightly radioactive core.
The sun fuses hydrogen into helium and releases tremendous amounts of energy. This is nuclear fusion. While the sun is a constant supply of energy, it is incorrect to state that, “The sun drives our climate.” Reality is more complex.
Our climate is driven by: Earth being a sphere, tilted on its axis, wobbling like a top, and the orbit being sometimes more ovular and sometimes more circular. This is why we have distinct climate zones, opposing seasons in the northern and southern hemispheres, a new North Star every 12,000 years, and why we had regular Ice Ages. We’ll delve into the Milankovitch Cycles in a later edition.
Earth is a materially closed, energetically open system. This means that, with some exceptions, like meteors/comets bringing novel minerals to the surface, Earth contains all of the material it will ever contain. We cannot obtain more ore for mining or more water for drinking and farming. Everything we have is everything we'll ever have. Being energetically open, however, means the sun is constantly bombarding us with energy in the form of visible, ultraviolet, and infrared light, and radio waves, x-rays, and gamma rays. We are supplied with energy forever (as far as humans are concerned!), but mind you: the sun is about halfway through its lifespan.
The Equator is hot and humid because, at the equinoxes, the surface of the equator is at 90 degrees to the sun, thereby receiving twice the amount of energy of the same area at a latitude of 60 degrees. This solar energy causes massive quantities of water to evaporate, which then condenses into clouds. This also creates a low-pressure system where warm air rises, reaches the top of the troposphere, then begins to cool and settle over the subtropics, ~23.5° latitude N and S. In these subtropical high-pressure systems we find dry deserts, where little moisture falls.
As the seasons change and we progress through the summer and winter solstices, the thermal equator shifts north and south of the true equator, driving the pressure changes that swing winds and weather systems north and south.
The temperate latitudes are at a less direct angle from the sun, experiencing variable solar energy and weather. The poles vacillate between sunless winter and summers when the sun doesn't set at all! This occurs at and above the Arctic Circle (66.5°N) during northern hemisphere summer solstice, and in the Antarctic Circle (66.5°S) during the southern hemisphere summer a.k.a. winter solstice.
The poles are the extremes of our Earth system, experiencing the largest fluctuation in solar energy. They are extremely fragile ecosystems that serve as the proverbial canary in a coal mine with regard to climate change. Stay tuned.
**Thank you to John Porritt for his corrections to a previous draft of this article. See his very helpful, well-articulated email below.**
“Hi Megan,
I'm so glad to have a science-based column addressing climate change in the Trinity Journal and wish you every success.
That said, I find one of your points misleading. The equator is hotter not because it is "physically closest to the sun"; the earth is millions of miles closer to the sun in January than in July. The reason the equator is hotter is because at the equinoxes the surface of the equator is at 90 degrees to the sun, therefore receiving twice the energy of the same area at a latitude of 60 degrees. At all other times, the thermal equator is north or south of the equator, driving the pressure changes and swinging the wind belts north or south. Due to this, Trinity County enjoys half a year of a desert climate and half a Pacific Northwest climate.
I will be following you with interest.
Best regards,
John Porritt”
Teamwork makes the dream work! Thank you, John, for your assistance in clarifying seasonal solar energy budgets on a spherical planet.
Image sourced from: https://www.livescience.com/our-solar-system.html
