10 Amazing Facts about the Sun

1. We only ever see what the sun looked like 8.3 minutes ago, because this is how long the light of the sun takes to reach the earth*. This is because we measure space is by light years – the amount of distance light travels in a year. A light year is around 6 million million miles, and the sun is 0.00001581 light years away. Another way to describe distances in space is astronomical units (AU). The Earth orbits the sun at a distance of around 93 million miles, or 152km and this is known as one AU.

2. A year is the amount of time it takes for the Earth to do a full orbit around the sun: this takes about 365 and a quarter day – the quarter is why we have an extra day every four years. Without the extra day in a leap year, our seasons would very gradually shift – by one day every four years. This means that around about every 700 years, we’d have fully flipped the seasons – if we didn’t add an extra day, in the UK we’d be celebrating midwinter in June and December would be the height of summer.

3. The sun is a star. There are lots of different types of star, but the distance from us to other stars means that they usually just look like a bright spot of light in the night sky to the naked eye. The sun looks as big as it does because it is relatively close to us. Our next nearest star is Proxima Centauri – at 4.246 light years away.

4. The sun is made of gases, held closely together by gravity – it really is just a burning ball of fire. It is the sun’s mass that creates the gravity that keeps the planets and other astronomical bodies in orbit around it. The sun makes up 99.8% of the mass of our whole solar system. It is difficult to imagine just how big the sun is, but we know that it would take about 1.3 million Earths to match its volume.

5. The sun is the centre of our solar system, and is orbited by 8 planets – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. There are even more dwarf planets, comets, meteors, rocks and dust in different orbits around the sun. Our solar system is just one of countless sun systems in our galaxy.

6. Stars are grouped into galaxies, and our sun is in a galaxy called the Milky Way. The sun is just one star in the Milky Way – a galaxy containing something between 100 billion and 400 billion stars. Scientists estimate that there are around 170 billion galaxies which can be observed using telescopes on Earth. Some of them contain around 100 trillion stars, each of which may be the centre of a solar system of planets. That’s a lot of suns, and a lot of planets.

7. The Sun rises over the horizon on Earth because of the rotation of the Earth, not because of movement of the sun. As the Earth rotates, it gradually exposes different aspects of its surface to the Sun, meaning that we cycle through day and night, and making it necessary to describe different time zones around the Earth.

8. When the sun rises, the skies over us on the Earth look bright. Compare this to pictures taken on the Moon, which only reflects about 3-12 percent of the sunlight that hits it (so it appears to shine). The sun lights up the sky the on Earth because of the atmosphere here. The light from the Sun in the daytime bounces off all the particles in the atmosphere – the particles and light rays just happen to make our sky blue.

9. We need sunlight on our skin to make vitamin D, but we can also get some vitamin D in our diet, or by taking supplements – this is especially important for those of us who keep our skin covered, and even more important when pregnant or breastfeeding. On the other hand, too much sunlight on our skin can cause sunburn, and even damage our skin cells enough to make us more prone to skin cancers.

10. The Earth is the only planet in our solar system that could support life as we know it, and we haven’t seen any evidence of life on other worlds. The Earth is in what is known as ‘The Goldilocks Zone’ – like the porridge in the story, it’s not too hot and not too cold. We’re exactly the right distance from the Sun to have warm days, variations in season and temperature around the globe, liquid water and solid ground. The Earth is just right.

*Never look directly at the sun, even for the shortest time, as it has the potential to cause eye damage.