The Sun

Everyday, your life is illuminated by Earth’s nearest and dearest star, the Sun.

Without the sun, there would be no life on Earth.

Its light energy, both visible and invisible, powers all plant life, terrestrial and aquatic. Because plants provide all the nutrients needed for all other organisms, the sun is vital to all ecosystems.

The sun drives Earth’s weather patterns, like the wind and the rain. It is also responsible for our ocean currents, affecting all life in our seas and oceans.

Let’s take a quick tour of our celestial neighborhood, our solar system.

Our sun is the center of our solar system. Every piece of matter in it orbits the sun, including the dwarf planets, comets, asteroid belt, and planets and their moons.

Although it may look different than the stars you can see at night, the sun is very much like them. Because it is so close to in comparison to other stars, it is much bigger and brighter. But if you were way out in space, it would twinkle in the backdrop of the universe along with its fellow stars.

When compared to other stars in the universe, our sun is a medium-sized star. But when compared to the size of the Earth, it’s enormous.

If you could fill the sun full of Earths, you could fit one million inside! Imagine how many Earths would fit in the largest stars in the universe!

Like many stars in the universe right now, the Sun is classified as a main-sequence star because, at about 5 billion years old, the sun is only midway through its life. Stars spend most of their lives in the main-sequence as it’s the “adulthood” of stars.

As it radiates energy in all directions from the center of our solar system, the sun is fueled by a nuclear chain reaction within its core where hydrogen fuses to become helium. This solar core is ten times more dense than lead with the energy it produces taking 100,000 years to reach the sun’s surface.

Once the energy from the sun’s core leaves the corona, the outermost layer, it will travel outward in all directions into space at the speed of light. That’s 186 thousand miles per second!

Do you know how long it takes the energy from the sun to reach the Earth?

About 8 and a half minutes!

The visible and invisible light from the Sun holds important information about the sun’s composition. This is exciting for astronomers because it makes it possible to study our great star from here on Earth.

For example, each element emits a unique pattern of light. By using a special instrument called a spectroscope when viewing the sun’s energy, astronomers can see the elements that make up the sun, as well as their relative amounts by looking at their spectrum.

Can you guess which element is the most abundant in main-sequence stars like our Sun? If you guessed hydrogen, you were right!

The sun is primarily composed of hydrogen, then helium. As the hydrogen fuses to become helium as the sun ages, the hydrogen amount will decrease as the helium amount increases. Helium fuses to make heavier elements as the sun continues to age, as well.