The ‘Star’ Of Our Solar System
The next time you get sun burnt from being outside too long spare a thought for how powerful that ball of energy is that dominates the daytime sky. The Sun warms our planet, provides the light by which we see and is necessary for life on Earth.
Our Sun produces poem worthy sunsets and as much energy as 1 trillion megaton bombs every second! Wow, that’s raw untapped power! Each morning, the sun rises in the east, makes its slow journey across the sky, and then sets in the west. The truth is that the Earth is orbiting the Sun. It’s the Sun that’s motionless, and the Earth that’s moving around it. The Earth rotates on its axis once every 24 hours, so that the Sun returns to roughly the same position in the sky every day.
If you could stare down at our planet’s north pole from a great height you would see the world spinning beneath you in an anticlockwise direction. As the day goes on, parts of the Earth which are to the west will get their chance to be in the sunlight, one after the other.
This is why sunrise on the east coast of Australia happens 3 hours before regions on the west coast. Hey, if you think it’s too shady where you live, think about this. There’s a town in the Italian Alps that does not get any direct sunlight for 84 days. However, the town fixed that by installing a giant mirror on the side of the mountain! True.
The Sun is a star, just like the other stars we see at night. The difference is distance. Other stars we see are light years away, while our Sun is only about 8 light minutes away, many thousands of times closer. The next time you see the sun rise from your place remember – it actually rose 8 minutes earlier!
We wouldn’t be here if the Sun wasn’t just the right distance away from planet earth. Our sun is a relatively small star but it would still hold the earth a million times over!
So, how close is the Sun? How old? And while we’re at it, will the Sun ever stop burning? The Sun has been “burning” for more than 4.5 billion years. In another 5 billion it will swell up to a hundred times its present size and burn most of the solar system up, us included.
Hang on, we say the Sun burns, but it doesn’t burn like wood burns. Instead, the sun is a gigantic nuclear reactor. The temperature at the surface of the Sun is about 5,600 Celsius, in the centre a whopping 15 million degrees Celsius. Feeling sweaty yet?
As you read this, the Sun is going through a mild but interesting period of activity. Last month we saw sunspots, cool areas on the Sun, up to 3 times bigger than the Earth. This week giant Solar flares were seen shooting away up to 70,000 kilometres in length. Our Sun is undergoing continuous change.
During the Cretaceous period, around 100 million years ago, Earth’s climate was so warm that there were no polar ice caps, and forests probably extended all the way to the South Pole. Local plants and dinosaurs evolved to live in continuous sunlight in the summer and darkness in the winter.
Want to see sunspots for yourself this weekend? It’s easy, just punch a hole through a piece of thin cardboard with a large knitting needle, point it at the Sun and hold a sheet of white A4 paper below. Sunspots will appear. Congratulations, you’ve just made a pin hole projector.