Sun Facts – The Pitfalls And Hardship
People don’t really know enough about the Sun facts. It supplies all of the energy in the Solar System. None of the planets would exist without it, and its influence on our tiny orb is immense.
This image, freshly collected at the time of writing, shows the Sun in the visible spectrum (suitably filtered to make a picture). There are very few sunspots today (immense areas that are a few thousand degrees cooler than average), but it is important to point them out because of one in particular. Do you see the one at the tip of the blue arrow? It is the same size as the entire planet Earth!
Spots on the Sun. Photo credit: NASA.gov
I can tell you that the Sun is 875,000 miles (1,392,000 kilometers) wide, depending on what you define as the surface, but it is really hard to grasp such large numbers in our brains that can barely manage planetary dimensions. I could say that the Sun is 99.85% of the mass in the Solar System, and that Jupiter is 66% of what is left, but it is still hard to grasp.
Sand grains measure about 1/75 of an inch (0.038 mm) on average, which is to say you would need to lay out seventy-five of them edge-to-edge to make a line one inch long (2.5 cm). Repeat that action 11,666 times to make a line 972 feet (296 meters) long. If you supposed that each grain represented one mile (1.6 km), then the total length (to scale) would represent the diameter of the Sun. On that same scale, the Earth would be 8,000 grains wide, or significantly less than 1% of the line’s length.
Despite the fact that you can block out the Sun with the tip of your finger held at arm’s length, it is still maddeningly, immensely, mind-bogglingly huge. This is incredibly hard to grasp for humans that are used to standing on level ground and seeing the horizon at a distance of 2.9 miles (4.7 km).
If you stand on a 100 foot (30 m) tall building or hill you can see 12.2 miles (19.6 km). If you stood on the observation deck of the CN Tower in Toronto, Ontario, Canada at a height of 1,135 ft. (346 m), on a clear day you could see all of 100 miles (160 km). We’re not mentally equipped to understand the scale of the Sun.
It’s too big to comprehend…
“Okay, forget that part then. You said all the energy we have comes from the Sun” you point out. “But what about fossil fuels, atomic energy, wind, solar or even geothermal?”
All of our energy, future or past, can be traced back to the Sun. Our Solar System grew out of an immense cloud of hydrogen gas that condensed, likely because it was disturbed by an uncomfortably close exploding supernova, which in turn provided all of the elements heavier than hydrogen.
All elements except hydrogen are made inside of stars and it was only when those early, early stars blew up that they spread out the materials necessary for building planets. The very oldest stars that are still burning probably don’t have solid planets (unless they captured some from other stars that blew up and flung their planets away); the exception would be proto-stars that didn’t have quite enough mass to ignite with nuclear fusion and become actual stars themselves. They would be similar to our gaseous giants like Jupiter, Saturn, Uranus, and Neptune, except composed entirely of hydrogen.
You are now more knowledgeable about the Sun than 90% of the people around you. But now it starts to get scarey…
You see, being that big, the Sun’s gravity crushes hydrogen together in its core causing it to fuse, and turns it into helium. This in turn releases an immense amount of energy which pushes back at the crushing gravity. Equilibrium is established and that determines what the overall diameter of the Sun is: gravity vs. nuclear explosion.
This is extremely stable when a sun is the size of our Sun. It’s been in balance like that for 4 ½ billion years, and has at least another five billion years ahead of it without any significant changes.
That’s not scarey
No, it’s not. That was to reassure you that our Sun isn’t going to explode any time in the next few billion years. I have something else for you to worry about.
The Sun has a very dense core. It is so dense that a photon of light created in the heart of the Sun, will never completely leave the Sun. Huh?
It won’t let go
This takes some explaining, but to skip the math, a photon created in the heart of the Sun is almost immediately broken down and its energy is mixed with other photons. In a matter of just a few minutes a small fraction of that energy has made into the surface and exited as light.
Most of the rest of it will remain inside the Sun exchanging back and forth with other photons as it is absorbed and re-emitted by atoms, and over the course of thousands, or even millions of years a large portion of it will eventually exit the Sun. A small portion of it will never leave, akin to the way you cannot get the last bit of toothpaste out of the tube.
Coronal mass ejection of the Sun. Credit: NASA. Read more here
All this energy exchange causes immense magnetic fields within the Sun. Occasionally when material at the surface is particularly energetic it will get blown off the surface hundreds of thousands of miles in giant arcs, almost as if contained within a hose.
It is actually tightly contained within the magnetic flux as a massive arch big enough to hold thousands of Earths. It can persist for months on end. Except…
There’s an Inner Sun and an Outer Sun
The magnetic field generated in the core of the Sun extends well past the surface, as you can see in the previous image. Here’s a fresh image of the magnetosphere of the Sun taken at the time of writing.
The problem arises because the core of the Sun seems to rotate as a solid body, but the outer third rotates at different speeds depending on the latitude from north to south. As a consequence the magnetic lines get severely twisted and then actually sheared off. This is the moment when mass which is ejected from the surface can escape the magnetic confinement and permanently leave the surface.
The magnetosphere of the Sun. Credit: NASA. Watch a video here
We call this a Coronal Mass Ejection or CME. Millions of tons of matter are accelerated to a million miles (1,609,000 km) per hour. That means it can make the trip to earth in 93 hours or just a little less than four days. When it gets here it can cause a Geomagnetic Storm, which can compromise satellites, on orbit spacecraft, and even the electrical grid on the Earth’s surface.
There are two pieces of good news
Good news #1:
CMEs occur quite frequently; even in a period of low solar activity they occur about once every five days. Fortunately, as pointed out earlier, this Sun is big—really big. There’s only a narrow band along the plane of the ecliptic, where a CME might actually be pointed at the Earth. If it occurs at any other point it simply cannot hit us. Combine this with the fact that there are 360° in that band and the odds of one hitting us diminish significantly.
Good news #2:
Like the starship Enterprise, our planet has some really good shields! The Earth’s core is a solid ball of iron, surrounded by molten iron that swirls around it. This creates a magnetic field which we used to navigate via compasses, or electronics in our phones that can read the field.
Solar wind diagram. Credit: NASA. Read more here
The Sun is constantly emitting particles and this is called the Solar Wind. Earth’s own magnetic field steers the solar wind aside. If it gets particularly intense, we can see Aurorae in the northernmost and southernmost portions of our planet’s sky. The particles that overwhelm our magnetic shield rain down on the poles where the field is weakest.
A powerful CME, on the other hand, could sweep our shields aside like it did on September 1, 1859. This was a huge Coronal Mass Ejection, and it was pointed straight in Earth. A storm of high energy electrons and protons forced our magnetic field aside, temporarily ripping into shreds, and it was… Beautiful!
More Sun Facts – Is it harmless?
You see, in 1859 our planet was largely unelectrified. Houses were lit by candles or burning gas; Edison wasn’t due to light up Menlo Park for another 20 years, in 1879.
People streamed outside to look at the Aurora Borealis, or the Aurora Australis, as it cloaked the entire planet. Reports of the time marveled at how it was so brilliant at night time from the light in the sky that you can read a newspaper. The shimmering curtains of green, yellow, purple, red, and blue encircled the planet like art performed by the gods. People were amazed and loved the wondrous display.
If the same thing happened today it could cause worldwide damage in the trillions of dollars.
Consider the smaller CME that struck the Earth in 1989. The Geomagnetic storm was so intense that it tripped the safety-system for Hydro-Quebec, plunging the largest province in Canada into complete darkness in just over one minute! It was a full 9 hours before the system could be brought back online, and only then by diminishing the system sensitivity to magnetic fluctuations of Earth’s own magnetic field. Many more electric grids in Russia and Scandinavian countries were affected. And this was a relatively small CME.
An event of the magnitude of the 1859 Coronal Mass Ejection could have crippled the planet, decimating electronics, telecommunications, and possibly inducing currents big enough in generators around the planet to destroy them. We could have lost all capability to generate electricity, plunging us back into the Dark Ages.
It would have taken us decades to be able to create the thousands and thousands of miles of wire that we would need, with skills equivalent to blacksmiths in the 1800s. We would need to rewind the turbines for Niagara Falls, Grand Coulee Dam, Hoover Dam, and innumerable nuclear generators, wind turbines, solar generators, and any car built after 1970.
But I’m not worried
Big events like this only occur about twice per millennia. Granted, we can always get small ones, but they’re largely an inconvenience rather than a threat. I’m sure we can manage without radio communication for a few hours.
For those big CMEs we have solar observatories that watch the Sun, and they can provide two days of warning before something major happens. That’s plenty of time to land all the aircraft, put all our radiation-hardened satellites into standby mode, disconnect our generating plants and short-out their coils so currents cannot be induced in them.
CMEs can be threatening; they could conceivably wipe out our civilization as we know it. But we have some safeguards in place and our intelligence to direct our actions. We should be safe.
Now if only we were to apply the same amount of thought and effort towards preparation for encounter with an asteroid or comet. A big impact like that could make for a really unhappy day for everybody…