Dave Reneke | A star 700 times larger than the Sun

GET OUT OF THE CITY: To get the best views of the night sky, you need to get away from light pollution of cities, know as skyglow.
GET OUT OF THE CITY: To get the best views of the night sky, you need to get away from light pollution of cities, know as skyglow.

We know about waste pollution here on Earth but I bet you didn’t know there was light pollution too. 

Skyglow from city buildings and street lights prevent large fractions of the Earth’s population from properly viewing the night sky.

It’s killing astronomy. So, if you’ve got a telescope, if you want to really see what’s out there, then get away from city lights.

Here’s a quick anecdote that will blow your mind.

In New York, years ago, there was a major blackout that lased 20 minutes.

Kids the next morning were telling their teachers they saw stars in the night sky for the first time in their lives.

Incredible!

There’s a generation of kids today who will never, ever get to appreciate the magnificence of our Milky Way.

“While we’re on a starry bent, grab your scope and pretend you’re setting up beside me in your backyard,” said Dave Reneke from Australasian Science Magazine.

“Together we’re going to look at a night sky favourite for March, the Orion constellation. You probably know it by a different name – it’s more commonly known as the ‘Saucepan.’ Rising in the east after sunset it’s perhaps the most recognizable constellation in the sky.”

“Check out the middle ‘star’ of the handle,” Dave added. “It’s not a star at all.

“It turns out to be a beautiful steel grey ‘nebula’ where millions of stars are being born, even as you read this. Now, look below the base of the Saucepan and you’ll see a red coloured star. That’s Betelgeuse, or ‘Beetlejuice’ as some call it.”

This is a red giant star, one of the biggest, 700 times larger than our Sun.

If you placed it where our Sun is now it would almost touch the orbit of Saturn! Now spin to the right of Orion and spot the brightest star in the night sky, Sirius.

It’s visible all night long and you don’t need a telescope to view it.

The distances involved here are amazing. Sirius is 8.6 light years away, meaning that the light you saw tonight took over 8 years to get here!

You see Sirius not as it looks now, but as it was all that time ago.

Hey, ever wondered what would happen if the sun disappeared?

Well, for eight and a half minutes we’d have no idea that the sun had gone. The sun would then blink out and night would fall over the entire Earth.

At that instant would Earth sail off in a straight line into space.

Over the course of several hours, the planets would wink out one by one, as they reflected the last of the sun’s light to us.

Whew!

Planet earth would quickly start to freeze over all life her would soon perish.

Dave Reneke is an astronomy teacher, writer and lecturer