By Shanuka Kadupitiyage
Ceylon Today Features
While you may not be able to experience snowballs in Sri Lanka, I’m sure you would have heard of them. Yes, those icy balls of snow that get thrown around by kids in foreign movies. However, did you know that far out in space, there are giant snowballs whizzing around us all year round?
Of course we’re talking about none other than comets. You might have heard of these good looking space objects more than once from science class or from books that you have read. If you aren’t aware of what comets are, and why they exist, then we’re here to clue you in on some important information.
Big, but small
If you were wondering how cold space is, the answer is that it’s cold enough to make the air you breathe turn into ice. If you mix together a bunch of these gases which have been frozen into ice, with chunks of rock and dust, you would’ve made a comet in your own little home.
However, the comets we know aren’t as tiny as you might expect. Most of them are as big as a small town. While they might be small when compared to planets and other things we find in space, they’re very big by our normal standards; you could even call them gigantic.
These giant ice balls circle the Sun. However, they like to do so very far from our resident fireball. Scientists say there could be billions of comets going in circles around the Sun as you are reading this today.
Most comets are found in the outer regions of the solar system, where it is the coldest. This area is called the Kuiper Belt and is littered with space debris such as asteroids and comets.
A comet’s orbit usually brings it closer to the sun in some point of its travel. When that happens, the icy materials heat up because of the Sun’s heat and spews out dust as well as gas while travelling through space. The boiling comet heats up to create what is called a coma, which becomes the head of the comet.
As the comet hurtles through space, the gases and dust that boils away from its body leaves a trail that can be seen for millions of kilometres. Since there’s no wind (or air as a matter of fact) to interrupt this trail of material, we can see this glowing trail of light in the night sky.
Since ancient history
People have been paying attention to comets appearing in the night sky from ancient times. The ancient Chinese astronomers kept very expensive records of comets they have seen in the night sky, even making drawings of their own, based on what they have seen.
One of the most famous comets in the world today is Halley’s Comet, which flies close enough for us to see every 75 years. The last time it was seen was in 1986, which means the next time we will see it in the sky would be in year 2061.
How old would you be when Halley’s Comet visits the Earth again? There’s a lot more you can learn about comets if you do a little digging in your library and on the internet. What else will you learn about these beautiful snowballs that fly across space while on fire?