Baring My Sol Trivia Quiz

Answer: Hydrogen

The Sun is, for the most part, a giant ball of hydrogen nuclei. About 74% of its mass is hydrogen, and roughly 92% of its atoms are hydrogen atoms. Helium makes up most of the rest at around 24% of the mass. Heavier elements like oxygen, carbon, and iron make up only a tiny fraction (less than 2%). In other words, the Sun is a massive, nuclear-powered hydrogen engine, which we'll look at more in the coming questions.

The energy released by those reactions eventually makes its way to the surface and radiates into space as sunlight. Every second, the sun converts about 600 million tons (500 billion kilograms) of hydrogen into helium, losing about 4 million tons (3.6 billion kilograms) of mass in the process. That "lost" mass becomes the sunlight that keeps us all alive and occasionally makes our skin peel.

Answer: Nuclear fusion

The Sun produces enough energy every second to power human civilization for millions of years. Deep within its core, where temperatures reach around 15 million degrees Celsius (27 million Fahrenheit) and pressures are crushing beyond imagination, hydrogen nuclei are forced so close together that they fuse to form helium. In doing so, a small fraction of their mass is converted into pure energy, as described by Einstein's famous equation, E = mc². 4 million tons (3.6 billion kilograms) every second packs quite a punch when you do the math.

The primary process in the Sun goes by the name of the proton-proton chain reaction. It begins when two protons fuse to form deuterium (a hydrogen isotope), releasing a positron and a neutrino. This deuterium nucleus then fuses with another proton to form helium-3, and two helium-3 nuclei combine to make helium-4, releasing more protons and (and here's the good part) vast amounts of energy in the form of gamma rays. That energy slowly diffuses outward through the solar layers before emerging as the sunlight that washes over the little blue ball we call home about eight and a half minutes later.

Answer: The Core

Every photon of light generated by the Sun that eventually reaches Earth begins its journey in the core, the central region that extends roughly from the Sun's center out to about a quarter of its radius. This is the only place in the Sun where conditions are extreme enough for nuclear fusion to occur. The temperature in the core soars to around 15 million degrees Celsius (27 million degrees Fahrenheit), and the pressure is more than 250 billion times Earth's atmospheric pressure. Under those conditions, hydrogen nuclei overcome their natural repulsion and fuse into helium, releasing massive amounts of energy.

The core is where the proton-proton chain reaction takes place, a series of steps that transform hydrogen into helium while producing energy in the form of gamma rays. These high-energy photons then begin a mind-bogglingly slow journey outward. It can take tens of thousands to hundreds of thousands of years for energy generated in the core to reach the Sun's surface, as it bounces aimlessly from particle to particle in the dense plasma like a pinball.

Answer: A white dwarf

When the Sun finally runs out of hydrogen fuel in its core in about 5 billion years from now (prepare accordingly) it will begin to die a horribly drawn-out death. The hydrogen fusion that keeps it stable will cease, and the core will start to contract under gravity while the outer layers expand outward. The Sun will blow up like a balloon until it turns into a red giant, engulfing Mercury, Venus, and possibly even Earth in the process. Its outer layers will then be cast off into space, forming a beautiful planetary nebula that nobody will be able to see. The planetary nebula is an ethereal sphere of glowing gas, marking the end of the Sun's mid-life crisis.

What remains after all that cosmic shedding is the core: a white dwarf. This dense, Earth-sized object will no longer produce energy through fusion. Instead, it will shine faintly from leftover heat, just a remnant of its former self (been there). A single teaspoon of white dwarf material would weigh several tons, as gravity compresses the Sun's entire mass into a volume comparable to Earth. It is stable, "degenerate matter", held up by quantum physics; particularly the "electron degeneracy pressure", which keeps it from collapsing any further.

That's what we know. However, over the course of TRILLIONS of years, even that faint glow is expected to fade. The white dwarf will cool and dim until it becomes a black dwarf, a cold, dark, and inert object radiating no light or heat. This is the Sun's final, hypothetical phase. It's hypothetical because the universe is not trillions of years old, so none actually exist.

Answer: Corona

The corona (from the Latin word meaning "crown") is the Sun's outermost atmosphere. During a total solar eclipse, when the Moon perfectly blocks the Sun's bright photosphere, the corona reveals itself as a spooky halo stretching millions of miles or kilometers into space. Under normal circumstances, the corona is completely overpowered by the Sun's brilliance, making eclipses one of the few opportunities to observe it directly with the naked eye, which of course you should never do.

Despite its seeming delicacy, the corona is HOT, reaching temperatures of over 1 million degrees Celsius (1.8 million Fahrenheit), hundreds of times hotter than the Sun's surface below it. This is counterintuitive and has had scientists pulling their hair out for decades, leading to what we lovingly call the "coronal heating problem". The leading suspects are tangled magnetic fields and violent waves of plasma that transfer energy from the Sun's surface into the outer atmosphere. NASA and the European Space Agency are working on solving the mystery as we speak.

Answer: Photosphere

The photosphere is what we think of as the Sun's "surface," even though, technically, the Sun doesn't have a solid surface in the least. The "surface" is really a thin layer of glowing gas, only about 500 kilometers (300 miles) thick, where the Sun's light finally escapes into space after bouncing around inside like a pinball for hundreds of thousands of years. When you look at the Sun (FunTrivia, its employees, administrators, and partners in no way endorse looking at the sun with the naked eye), what you're seeing is this layer.

Temperatures in the photosphere hover around 5,500 degrees Celsius (about 10,000°F), which is cool compared to the layers above it. Not that I recommend setting your thermostat to that temperature. It's more than hot enough to vaporize pretty much anything you could throw at it, if you could throw anything at it.

Just above the photosphere lies the chromosphere, and beyond that, the corona, each level hotter than the last. The light we see from the photosphere takes only about 8 minutes to travel the roughly 150 million kilometers (93 million miles) to Earth, yet it's the culmination of a tediously long process of nuclear fusion, radiation, and convection.

Answer: Astronomical Unit

The Astronomical Unit, or AU, is the standard yardstick (meterstick) of the solar system. It was originally defined as the average distance between Earth and the Sun, but has since been officially defined as exactly 149,597,870.7 kilometers (roughly 93 million miles). This means that when some science fiction writer (I'm looking at you, Liu Cixin) says something is about 5 AU from the Sun, you can imagine it sitting five times farther out than Earth. (That's just shy of Jupiter, by the way.)

The AU is pretty handy because it gives astronomers a way to compare distances in our solar system without juggling enormous numbers. For instance, Mercury orbits at about 0.39 AU, while Neptune keeps to itself 30 AU away. Spacecraft missions are also planned in terms of AUs. NASA's Voyager 1 crossed 100 AU in 2012, crossing the heliopause and entering interstellar space.

Answer: Magnetic fields

Sunspots may look like ugly blemishes on the Sun's otherwise pretty face, but they're actually regions of intense magnetic activity. These meddling magnetic fields twist and tangle, disrupting the normal flow of hot plasma rising from the Sun's interior. With the upward flow of heat temporarily hindered, the affected region cools to around 3,800°C (about 6,800°F), still on the warm side, but several thousand degrees cooler than the rest of the photosphere. That temperature difference is why sunspots appear dark by contrast though, if you could isolate one, it would glow brightly all by itself.

Sunspots tend to appear in pairs or clusters, with opposite magnetic polarities, like the north and south poles of a bar magnet. They're part of the Sun's larger 11-year solar cycle, during which magnetic activity waxes and wanes, leading to periods of frequent sunspots and solar flares (the "solar maximum") followed by calmer intervals (the "solar minimum"). These variations can influence space weather and even have subtle effects on Earth's climate and tech.

Answer: Solar Wind

The solar wind is a continuous stream of charged particles flowing outward from the Sun's corona, its outermost atmosphere. It is made up mostly of electrons, protons, and alpha particles, which are basically helium nuclei (a happy family of two protons and two neutrons). While it may sound romantic, this "wind" blows at speeds of 400 to 800 kilometers per second (900,000 miles/hour to almost 2 million miles/hour), fast enough to reach Earth in just a few days. It's definitely not a breeze you'd want to feel up close. The solar wind is a plasma, a nasty soup of electrically charged particles that can strip electrons from atoms and wreak havoc on electronics in space.

This outflow doesn't just vanish into the void. The solar wind creates a massive bubble called the heliosphere, which envelops our entire solar system and acts as a kind of protective shield against cosmic rays from deep space. The boundary of this bubble, the heliopause, is where the solar wind finally loses its battle of momentum against the interstellar medium. Spacecraft like Voyager 1 and 2 have crossed this frontier, becoming humanity's first true interstellar ambassadors.

When the solar wind encounters Earth's magnetic field, a fascinating tug-of-war begins. The magnetosphere, our planet's magnetic shield, deflects most of the incoming charged particles, but some slip through near the poles. There, they collide with oxygen and nitrogen in the upper atmosphere, creating auroras (the northern and southern lights). Occasionally, powerful bursts in the solar wind, like coronal mass ejections, can overwhelm this defense, causing geomagnetic storms that disrupt satellites, GPS, and sometimes even electrical grids.

Answer: Prominences

Prominences are enormous, arching loops of glowing gas (plasma) which rise up from the Sun's surface, often stretching hundreds of thousands of kilometers into space. They are anchored to the photosphere and extend outward into the corona, shaped and held in place by the Sun's tangled magnetic fields.

From Earth, through special solar filters, they appear as bright red or pink features, sometimes quite dynamic. A single prominence can be so large it could loop around the entire Earth several times over.

Prominences are composed mostly of hydrogen and helium, and they can last for days or even weeks. When stable, they look like pretty, glowing arches suspended in space. When they become unstable, however, all that plasma can erupt in a dramatic event known as a coronal mass ejection (CME), flinging billions of tons of material into the solar system at amazing speeds. If one of these eruptions is directed toward Earth, it can trigger intense geomagnetic storms, disrupting satellites, power grids, and communications systems.

When the solar wind and CMEs from such prominences collide with Earth's magnetosphere, our planet's magnetic field deflects most of the charged particles, but not all. Some get funneled along the magnetic field lines toward the poles, where they excite atmospheric gases and produce the auroras at the poles.