7 Shining Facts About the Sun

NASA
NASA

Isaac Asimov described the solar system as the Sun, Jupiter, and debris. He wasn't wrong—the Sun is 99.8 percent of the mass of the solar system. But what is the giant ball of fire in the sky? How does it behave and what mysteries remain? Mental Floss spoke to Angelos Vourlidas, an astrophysicist and the supervisor of the Solar Section at Johns Hopkins University Applied Physics Laboratory, to learn what scientists know about the Sun—and a few things they don't.

1. IT'S A GIANT NUCLEAR FUSION REACTOR.

The Sun is so incomprehensibly big that it's almost pointless to bother trying to imagine its size. Our star is about 860,000 miles across. It is so big that 1.3 million Earths could fit inside of it. The Sun is 4.5 billion years old, and should last for another 6.5 billion years. When it faces the final curtain, it will not go supernova, however, as lacks the mass for such an end. Rather, the Sun will grow to a red giant—destroying the Earth in the process, if we last that long, which we won't—and then contract down to become a white dwarf.

The Sun is 74 percent hydrogen and 25 percent helium, with a few other elements thrown in for flavor, and every second, nuclear reactions at its core fuse hundreds of millions of tons of hydrogen into hundreds of millions of tons of helium, releasing the heat and light that we love so very much.

2. IT HAS A GALACTIC-SCALE ORBIT.

The Sun rotates, though not quite the same way as a terrestrial planet like the Earth. Like the gas and ice giants, the Sun's equator and poles complete their rotations at different times. It takes the Sun's equator 24 days to complete a rotation. Its poles poke along and rotate every 35 days. Meanwhile, the Sun actually has its own orbit. Moving at 450,000 miles per hour, the Sun is in orbit around the center of the Milky Way galaxy, making a full loop every 230 million years.

3. IT'S HOT IN ODD WAYS.


The solar corona as captured every two hours for four days. Red is cool (~80,000°F), while yellow is hot (~2,800,000°F).
Angelos Vourlidas, JHU/APL

The Sun's temperatures leave astrophysicists puzzled. At its core, it reaches a staggering 27,000,000°F. Its surface is a frosty 10,000°F, which, as NASA notes, is still hot enough to make diamonds boil. Here's the weird part, though. Once you get into the higher parts of the Sun's corona, temperatures again rise to 3,500,000°F. Why? Nobody knows!

4. THE SUN HAS AN ATMOSPHERE—AND THE EARTH IS INSIDE IT.

If you saw the total solar eclipse earlier this year, you saw the Sun turn black, ringed by a shimmering white corona. That halo was part of the Sun's atmosphere. And it's a lot bigger than that. In fact, the Earth is inside of the Sun's atmosphere. "It basically goes as far away as Jupiter," Vourlidas tells Mental Floss. The Sun is a semi-chaotic system. Every 100 years or so, the Sun seems to go into a small "sleep," and for two or three decades, its activity is reduced. When it wakes, it becomes much more active and violent. Scientists are not sure why that is. Presently we are in one of those solar lulls.

5. THE IRON IN YOUR BLOOD COMES FROM THE SUN'S SIBLINGS.

The Sun lacks a solid core. At 27,000,000°F, it's all plasma down there. "That's where most of the heavy elements like iron and uranium are created—at the cores of stars," Vourlidas says. "When the stars explode, they are released into space. Planets form out of that debris, and that's where we get the same iron in our blood and the carbon in our cells. They were made in some star." Not ours, obviously, but a star that exploded in our neighborhood before our Sun was born. Other elements created from the cores of stars include gold, silver, and plutonium. That is what Carl Sagan meant when he said that we are children of the stars.

6. THE HOLY GRAIL OF SUN SCIENCE IS UNDERSTANDING ERUPTIONS.

The ability to predict solar storms is the holy grail for astrophysicists who study the Sun. During a coronal mass ejection, a billion tons of plasma material can be blown from the Sun at millions of miles per hour. The eruptions carry around 300 petawatts of energy—that's 50,000 times the amount of energy that humans use in a single year. As the structures travel from the Sun, they expand, and when they hit the Earth, a percentage of their energy is imparted. Those impacts can create havoc. Spacecraft are affected, airliners receive surges of x-rays, and the energy grid can be disrupted—one day perhaps catastrophically so. "Our models say it can happen every 200 years," says Vourlidas, "but the Sun doesn't know about our models."

The last such strike on the Earth is believed to have occurred in 1859. The telegraph system collapsed, but the effect on society was minimal overall. (The widespread use of electric lighting and the first power grids were still decades away.) If the Earth were to sustain a similar such destructive event today, the effects might be devastating. "It is the most violent phenomenon in our solar system," Vourlidas explains. "We need to know when such an amount of plasma has left the Sun, whether it will hit the Earth, and how hard it is going to slap us." Such foresight would allow spacecraft to power down sensitive instruments and power grids to switch off where necessary, among other things.

7. NASA'S NEXT STOP: THE SUN.


Wind moving off of the Sun in visible light. If you were in a spaceship and didn't melt, that's what you would see. The zooming effect simulates what an imager on the Parker Solar Probe will see.
Angelos Vourlidas, JHU/APL

Next year, NASA will launch the Applied Physics Laboratory's Parker Solar Probe to "kiss" the Sun. It will travel to within 4 million miles of our star—the closest we've ever come—and will study the corona and the solar wind. "At the moment, the only way we understand that system is by seeing what the properties of the wind are at Earth, and then trying to extrapolate back toward the Sun," says Vourlidas. "It's an indirect exercise. But the probe will measure the wind—how fast it is, how dense, what is the magnetic field—across multiple locations as it orbits the Sun." Once scientists get those measurements, theorists will attempt to devise new models of the solar wind, and ultimately help better predict solar storms and space weather events.

Editor's Note: This post has been updated. 

What Happens to Your Body If You Die in Space?

iStock.com/1971yes
iStock.com/1971yes

The coming decades should bring about a number of developments when it comes to blasting people into orbit and beyond. Private space travel continues to progress, with Elon Musk and Richard Branson championing civilian exploration. Professional astronauts continue to dock at the International Space Station (ISS) for scientific research. By the 2040s, human colonists could be making the grueling journey to Mars.

With increased opportunities comes the increased potential for misadventure. Though only 18 people have died since the emergence of intragalactic travel in the 20th century, taking more frequent risks may mean that coroners will have to list "space" as the site of death in the future. But since it's rare to find a working astronaut in compromised health or of an advanced age, how will most potential casualties in space meet their maker?

Popular Science posed this question to Chris Hadfield, the former commander of the ISS. According to Hadfield, spacewalks—a slight misnomer for the gravity-free floating that astronauts engage in outside of spacecraft—might be one potential danger. Tiny meteorites could slice through their protective suits, which provide oxygen and shelter from extreme temperatures. Within 10 seconds, water in their skin and blood would vaporize and their body would fill with air: Dissolved nitrogen near the skin would form bubbles, blowing them up like a dollar-store balloon to twice their normal size. Within 15 seconds, they would lose consciousness. Within 30 seconds, their lungs would collapse and they'd be paralyzed. The good news? Death by asphyxiation or decompression would happen before their body freezes, since heat leaves the body slowly in a vacuum.

This morbid scene would then have to be dealt with by the accompanying crew. According to Popular Science, NASA has no official policy for handling a corpse, but Hadfield said ISS training does touch on the possibility. As he explained it, astronauts would have to handle the the body as a biohazard and figure out their storage options, since there's really no prepared area for that. To cope with both problems, a commander would likely recommend the body be kept inside a pressurized suit and taken someplace cold—like where garbage is stored to minimize the smell.

If that sounds less than regal, NASA agrees. The company has explored the business of space body disposal before, and one proposition involves freeze-drying the stiff with liquid nitrogen (or simply the cold vacuum of space) so it can be broken up into tiny pieces of frozen tissue, which would occupy only a fraction of the real estate that a full-sized body would.

Why not eject a body, like Captain Kirk and his crew were forced to do with the allegedly dead Spock in 1982's Star Trek II: The Wrath of Khan? Bodies jettisoned into space without a rocket to change their trajectory would likely fall into the wake of the spacecraft. If enough people died on a long trip, it would create a kind of inverted funeral procession.

Even if safely landed on another planet, an astronaut's options don't necessarily improve. On Mars, cremation would likely be necessary to destroy any Earth-borne bacteria that would flourish on a buried body.

Like most everything we take for granted on Earth—eating, moving, and even pooping—it may be a long time before dying in space becomes dignified.

[h/t Popular Science]

Have you got a Big Question you'd like us to answer? If so, send it to bigquestions@mentalfloss.com.

Life on Nearby Exoplanet Barnard's Star B Might Be Possible, According to Astronomers

iStock.com/PavelSmilyk
iStock.com/PavelSmilyk

Despite contradictory statements from UFO eyewitnesses, we have yet to confirm the presence of intelligent life beyond Earth. But astronomers continue to flirt with that hope. The most recent speculation comes from Barnard’s Star, the second-closest star system to Earth, which is circled by a frozen super-Earth dubbed Barnard's Star b. While its surface might be as cold as -274°F, there may just be potential for life.

According to CNET, the chilly Barnard's Star b—located 6 light years away from Earth—could still be hospitable to living organisms. Astrophysicists at Villanova University speculate the planet could have a hot liquid-iron core that produces geothermal energy. That warmth might support primitive life under the icy surface. A similar situation could possibly occur on Jupiter’s moon, Europa, where tidal heating might allow for subsurface oceans containing living things.

Barnard's Star b has a mass just over three times that of Earth. The conclusions about potential life were drawn by Villanova researchers from 15 years of photometry examination of the solar system [PDF].

“The most significant aspect of the discovery of Barnard’s star b is that the two nearest star systems to the Sun are now known to host planets,” Scott Engle, a Villanova astrophysicist, said in a statement. “This supports previous studies based on Kepler Mission data, inferring that planets can be very common throughout the galaxy, even numbering in the tens of billions. Also, Barnard’s Star is about twice as old as the Sun—about 9 billion years old compared to 4.6 billion years for the Sun. The universe has been producing Earth-size planets far longer than we, or even the Sun itself, have existed.”

Scientists hope to learn more about the potential for life on Barnard's Star b as new, more powerful telescopes are put into use. NASA’s delayed James Webb Space Telescope could be one such solution. Its 21-foot mirror—three times the size of the Hubble—is set to open in 2021.

[h/t CNET]

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