The sun is the center of everything, and that's not just something we say to show how important it is. The sun is quite literally in the center of our solar system. Everything else — planets, comets, asteroids — revolves around it. The sun is what keeps everything in its place.
The sun is a star, one of about 100 billion in the Milky Way galaxy. It's an extremely important star for all the living things on Earth. Without it, we — and all other living things — would cease to exist. We have the sun to thank for the seasons and ocean currents, and it also influences the weather.
Read on to learn some interesting facts about the sun.
It's our nearest star neighbor
The sun is a star, and it's the closest star to Earth. Of course, close is a relative term. Even though it’s our closest star neighbor, it's really nowhere near Earth. It's more than 93 million miles away from our home planet. Let's compare that to Venus, our closest planetary neighbor. When Earth and Venus are at their closest point to each other, they are about 38 million miles apart. Earth and Venus are usually much farther away from one another than 38 million miles, however. In fact, many times Mercury is closer to us on Earth than Venus.
So how long would it take to travel to the sun? On a plane flying 550 mph, it would take 19 years. But a spacecraft can fly much faster than a plane. Consider that NASA's Mars Curiosity rover took between eight and nine months to reach Mars, traveling at about 8,400 mph. At that speed, it would take a little more than 15 months to reach the sun.
It's got a lot of star power
Not only is the sun the closest star to Earth, it's the only star in our entire solar system. It's also the largest object in the solar system. It’s so large you could fit 1.3 million Earths inside it. Put another way, the sun is 100 times as wide as Earth and 10 times as wide as Jupiter, the largest planet in our solar system. And you would need more than 330,000 planets the size of Earth to equal the mass of the sun.
Words to know
Axis: An imaginary line on which something rotates.
Plasma: An ionized gas that is one of the four states of matter.
Revolve: To orbit another object.
Rotate: To move in a circular motion on an axis.
And you know the sun is hot, but do you know just how hot it is? At its core, temperatures reach about 27 million degrees Fahrenheit. All that heat is essential because it creates the pressure needed to support its mass. Without that pressure, the sun would collapse on itself.
You know that saying "as hot as the surface of the sun"? Well, the sun doesn't actually have a surface. Instead, it's a giant ball of plasma. What we perceive to be the "surface" of the sun is a photosphere, which is sort of like an envelope around a star from which the light and heat radiate.
It won't last forever
All good things must come to an end, and the sun won't shine forever either. It's been burning bright for more than 4.5 billion years, but eventually it will burn out when it runs out of fuel.
The sun burns hydrogen for fuel. Lucky for us, there's plenty of hydrogen left in the sun. Experts believe the sun has enough fuel to burn bright for another 5 billion years.
When the sun runs out of hydrogen in its core, it can no longer support itself. It will continue to burn the hydrogen around the core and expand into a red giant star. When this happens, it will completely engulf Mercury and Venus — the two planets closest to the sun — and will likely engulf Earth as well. As time goes on, the sun will lose its mass, eventually leaving behind a carbon core. Once the carbon core cools, the sun will be a white dwarf, which is the remnant of a star.
It's not that big by star standards
The sun is the biggest, brightest object in our solar system, but among the billions of stars in the Milky Way galaxy it's just average. It is classified as a medium-sized star, and there are stars out there that are much bigger than the sun.
Consider the star called Betelgeuse. It's 700 times larger than the sun, and 14,000 times brighter. The largest known star so far is one called UY Scuti. It has a radius 1,700 times larger than the sun's. That means 5 billion stars the size of the sun could fit inside UY Scuti. Of course, if the sun is a medium-sized star, there must be plenty of smaller stars out there as well. Some stars are quite small by the sun's standard, only about a 10th of the size.
It rotates just like the planets
All the planets in our solar system revolve around the sun, and they also all rotate on an axis. Each rotation is the length of a day, and each revolution around the sun amounts to a year. On Earth, a full rotation takes about 23 hours and 56 minutes, and a full revolution takes about 365.25 days. Different planets rotate and revolve at different speeds. On Venus, a day lasts 5,832 Earth hours, while a day on Neptune lasts 16 Earth hours. A year on Venus is 225 days, and a year on Neptune lasts 60,190 days.
While all this rotating and revolving is taking place, the sun itself is rotating on its axis too. (It doesn't revolve, though, because it is the center of the solar system — it is the thing everything else revolves around.) Because the sun is not a solid object, it doesn't spin like Earth does. It spins faster at its equator than it does at its poles. At its equator, it takes the equivalent of 25 Earth days to complete a rotation, and at its poles one rotation takes 36 days.
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