There’s nothing small about the sun, even if it’s often categorized as a yellow dwarf. Heat and light from the sun travel 93 million miles to Earth to make all life possible, a capacity that no other star in the universe is known to have. Humankind wouldn’t have been able to grow crops, navigate the seas, or design Stonehenge without it. Read on for more about the glowing ball of gas at the center of our solar system.

The Sun Formed About 4.6 Billion Years Ago

Before the sun was the sun, it was a swirling cloud of dust and gases known as the solar nebula. As this cloud spun around in space, the material in its center condensed under the force of its own gravity and formed an incredibly massive disk of stellar debris — in other words, a baby sun. The nebula’s remaining dust spun off to form the planets, dwarf planets, asteroids, comets, and other bodies that populate our solar system.

The Sun’s Core Is a Nuclear Reactor

The sun is not a solid sphere like Earth. It’s a dense ball of gases organized into layers. At its center, the core’s density of 150 grams per cubic centimeter is about 13 times denser than lead, and its temperature can reach 15,000,000 degrees Celsius (about 27,000,000 degrees Fahrenheit). The extreme heat causes nuclear fusion of hydrogen into helium, creating enormous amounts of energy that radiate outward through the sun’s other layers. Eventually, the energy reaches the photosphere, which we view as the sun’s fiery “surface” (though it’s not actually on fire). This energy is finally released from the corona, the sun’s outermost layer, as light, heat, charged particles known as solar wind, and other forms. It takes more than 170,000 years for energy to travel from the sun’s core to Earth, but only 8.5 minutes for it to travel from the corona to Earth.

The Sun Is 330,000 Times More Massive Than Earth

There’s no denying it — the sun is ginormous. The star is about 10 times bigger than Jupiter, the largest planet. Its diameter of 865,370 miles dwarfs Earth’s diameter of 7,926 miles; in fact, you could theoretically fit more than 1 million Earths into the sun. In addition to being the largest body in our entire solar system, the sun contains more than 98% of all the mass in the solar system, exerting enough gravitational pullto keep all of the planets, asteroids, and other celestial bodies in orbit.

Energy can erupt from the sun’s corona as big bursts of radiation called solar flares, or as streams of plasma known as coronal mass ejections. This magnetically charged activity — called space weather — can reach Earth’s magnetic field and ionosphere (where the Earth’s atmosphere meets space), affecting the performance of technology. Electromagnetic storms can cause electrical surges and blackouts, disrupt telecommunications, and damage global positioning systems and satellites. Yet space weather also gives us the northern and southern lights: When electrons emitted from the sun bump into the upper layers of our atmosphere, they collide with oxygen and nitrogen and transfer their energy to those atoms. The atoms then release that energy as light, often visible in the polar regions where Earth’s magnetic field is strongest.

The Carrington Event Was the Most Intense Electromagnetic Storm Ever Recorded

Sunspots are areas of extreme magnetic activity in the sun’s photosphere, and for centuries, scientists have associated their presence with electrical anomalies on Earth. In September 1859, British astronomer Richard Carrington was surprised to look through his telescope and see a group of sunspots rapidly change, flash, and disappear. The following morning, Earth’s atmosphere blazed with purple, green, and red aurorae even in the tropics, while electricity surged through the world’s telegraph wires and lit the telegrams on fire.

Carrington had made the first observation of a solar flare, and it just happened to be the most powerful one of the last 500 years, according to NASA. It was determined to be a white-light solar flare, an exceedingly powerful type in which the sun somehow causes electrons to move faster than half the speed of light. The flare is believed to have signaled a huge coronal mass ejection, which led to the dazzling aurorae.

Yes, the Sun Will Probably Engulf Our Planet

Like all stars, the sun will eventually fizzle out. In a couple of billion years, it will run out of hydrogen in its core, leaving behind helium as the product of nuclear fusion. The core isn’t hot enough to “burn” helium, so gravity will begin to collapse the core into itself, forcing the fusion of the few remaining atoms of hydrogen around the core. At the same time, the core’s contraction will allow the sun’s outer layers to expand. The hydrogen fusion will increase the sun’s brightness, while the expansion cools the surface temperatures of the photosphere and corona. At this stage, the sun will transform from a yellow dwarf to a red giant.

Astrophysicists predict that the sun’s surface will expand as far as the vicinity of Mars. Earth will be pulled into the center of the red giant and disintegrate. But let’s look on the bright side — by that time, the sun’s brightness will have increased and the resulting heat will have evaporated Earth’s oceans and made our planet uninhabitable.

Finally, at the end of its life cycle about 5 billion years from now, our sun will spend all of its energy and cast off its outer layers, becoming a white dwarf — a dim shell of its former glory.