The Sun Power: What the Sun Is and How It Moves

The Sun Power is a simple guide to the star that gives Earth light, heat, and life. This article answers seven common questions about the Sun in short, clear paragraphs. It also explains how the Sun moves in space and how that motion looks from the ground.

NASA and other space agencies describe the Sun as a real star, not a fire on the sky. The facts below follow that science. A later section notes related Quran verses about the course of the Sun, without mixing worship with physics.

What is the Sun? It is a star, the only star in our solar system.

NASA calls the Sun a 4.5-billion-year-old yellow dwarf. It is a huge, glowing ball of hot hydrogen and helium gas, called plasma, held together by gravity.

The Sun sits at the center of the solar system. Its gravity holds the planets, moons, asteroids, and comets in orbit. The Sun holds about 99.8% of all the mass in the solar system.

Without the light and heat of the Sun, life on Earth as we know it could not exist. That is the real meaning of The Sun Power for this planet.

The diameter of the Sun is about 1.4 million km (865,000 miles). That is about 109 times the width of Earth. About 1.3 million Earths could fit inside the Sun.

Because we stand on a turning planet, the Sun appears to rise in the east, cross the sky, and set in the west.

On a daily timescale, the Sun is almost still relative to Earth. The daily journey of the Sun across the sky is Earth’s rotation. It is not the Sun flying around the planet.

This is the first key in The Sun Power: the path you watch at dawn and dusk is mostly Earth’s spin.

The Sun Power is easier to understand if you separate the scales: the daily path in the sky, Earth’s yearly orbit, the spin of the Sun, and the long trip around the galaxy.

Earth and the other planets orbit the Sun. The Sun does not orbit Earth each year. This is the heliocentric model.

Earth takes about 365.25 days to complete one orbit. That orbit is one year. The average distance from Earth to the Sun is about 150 million km (93 million miles).

The Sun Power of this system is the star at the center: the planets and the Sun also orbit a shared center of mass called the barycenter. Because the Sun is so massive, that point usually lies inside or very near the Sun. So we still say the planets orbit the Sun.

The whole solar system — the Sun plus the planets — orbits the center of the Milky Way. That trip takes about 230 million years. The speed is about 720,000 km/h.

The Sun also spins on its own axis. It takes about 25 days at the equator and about 36 days near the poles. This is called differential rotation, because the Sun is not a solid ball.

So how the Sun moves depends on the scale: daily sky path, yearly orbit of Earth, spin of the Sun, and the long trip around the galaxy. The Sun Power covers all four of those scales in one place.

There is no single fixed starting place for the Sun on Earth. The Sun Power is a simple way to name the light we see at dawn and dusk.

Because Earth rotates west to east, the Sun appears to rise in the east and set in the west in most places. Near the poles, polar day and polar night can break that simple pattern. The Sun Power still reaches those places, but the daily rise-and-set pattern can stop for weeks or months.

The Sun rises exactly due east and sets exactly due west only on the two equinoxes. Those dates fall around 20–21 March and 22–23 September.

In other seasons the rise and set points of the Sun shift. That shift is part of how The Sun Power appears across the year.

Places farther east see the Sun first. That is why Japan is called the Land of the Rising Sun. Places farther west see the Sun later.

Times also change with latitude and season. Earth’s axis is tilted about 23.5°. That tilt is why seasons change the path of the Sun.

Officially, sunrise is the moment the upper edge of the Sun appears on the horizon. Air bends the light, so the Sun can appear a little earlier than its true geometric position. That first edge of light is the start of The Sun Power for that day.

Yes. Almost all of Earth’s heat and light come from the Sun. That is The Sun Power in daily life.

Heat from the Sun does not travel through empty space by touch. It does not need moving air. The Sun Power travels as electromagnetic radiation — mostly visible light and infrared — at the speed of light.

Light from the Sun takes about 8 minutes 20 seconds to reach Earth.

When that radiation hits land, oceans, and air, it is absorbed and turned into heat. The ground then warms the air. Earth’s atmosphere also traps some outgoing infrared heat. That greenhouse effect helps keep the planet livable.

Only a tiny fraction of the total energy of the Sun hits Earth. The rest spreads into space. Even that small share of The Sun Power is enough to drive weather, crops, and the warmth we feel.

Large objects in space become round because of gravity. The Sun Power starts with that fact: the Sun looks circular because gravity shaped it.

When the Sun formed from a collapsing cloud of gas and dust, gravity pulled material toward the center. The most stable shape under that pull is a sphere. That is why the Sun looks circular.

The Sun is one of the roundest natural objects ever measured. It is not a perfect sphere. It is very slightly flattened at the poles because it rotates. The flattening is tiny, about 0.00005. Gravity is so strong that the difference is almost invisible.

From Earth the Sun looks like a perfect disk because we see a distant sphere face-on. That is the second point The Sun Power makes about its shape.

The temperature of the Sun is not one number. Each layer is different. NASA values are below.

The core of the Sun is hot enough for nuclear fusion. Hydrogen nuclei fuse into helium and release the energy that becomes sunlight. That process is the engine of The Sun Power.

The outer corona of the Sun is hotter than the visible surface. Scientists still study why.

Nothing can live on the Sun. The energy that leaves the Sun, after traveling 150 million km, is what warms Earth.

From the ground, the Sun appears to rise in the east, cross the sky, and set in the west. Astronomy explains that daily path as apparent motion. Earth turns west to east once in about 24 hours. The Sun is not flying around Earth each day.

That does not mean the Sun is still. The Sun Power also covers the real motion of the Sun. The Sun spins. Planets pull the Sun slightly around the barycenter. The solar system travels around the Milky Way.

Some readers also ask about verses that say the Sun runs on a course. Those lines speak of order and an appointed term. They do not have to mean that the Sun orbits Earth every 24 hours. The Sun Power keeps that science and those verses side by side, without mixing worship with physics.

Science describes how the daily sky path of the Sun is produced, and how the Sun also moves in space. These verses describe the Sun and Moon as ordered and limited to a set course, so day and night keep their turn.

The Sun Power treats them as different kinds of statement. One is a physical model. The other is a statement of order and decree.