Daily BulletinHoliday Centre

The Conversation

  • Written by Jake Clark, PhD Candidate, University of Southern Queensland

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

Why do stars twinkle? – Max, 4, Earlwood.

Max, that’s a fantastic question! And the answer, it turns out, is all around us.

Have you ever been out on a really hot day? Like ice-cream-melting-through-your-hands hot? Well, if you have, you may have noticed trees near the horizon being a bit wobbly or blurry. It looks strange, and something very similar is happening when we see stars twinkle in the night sky.

image The light from the setting Sun bends through the atmosphere creating a mirage. This mirage behaves the same way as a star’s twinkling light. Brocken Inaglory

When we look up, we don’t just look into space. We’re actually looking at space through all of the air above us, called the atmosphere.

The Earth’s atmosphere is a layer of air. A whopping 120 kilometres tall, or more. This air, around and above us, moves and swirls around the Earth at different speeds.

How fast this air travels, depends on its temperature. When the air is hot, it has loads of energy and loves to move around. But when the air is cold, it doesn’t move as much.

Hot air is also lighter than cold air, so it rises past, and mixes with, the cold air around it. This mixing creates swirls in the atmosphere known as “turbulence”.

image van Gogh’s painting ‘The Starry Night’ artistically shows the stars light being swirled by turbulence in our atmosphere. Vincent van Gogh, Wikimedia

Air can also be bumped around as it passes up and down hills and mountains on the Earth’s surface, creating waves that reach into the upper atmosphere. These waves disturb the air above, also causing turbulence.

image Air can be can be pushed up as it passes above mountains and hills, creating waves in the atmosphere. These waves can create really cool cloud patterns like this near the Moul n'ga Cirque in Southeast Algeria. Pir6mon/wikimedia

As light from a star races through our atmosphere, it bounces and bumps through the different layers, bending the light before you see it. Since the hot and cold layers of air keep moving, the bending of the light changes too, which causes the star’s appearance to wobble or twinkle.

Indigenous Australians and Torres Strait Islanders have been observing the twinkling of stars for thousands of years. The stars’ twinkling shows how the winds are moving, which can really help when predicting weather - like really hot days.

Correcting the twinkle

While twinkling looks pretty, astronomers find it very annoying. This is because it blurs the things we want to see, like distant galaxies.

What can we do about this?

Well, space is the best place to see a star without a twinkle. However, getting big telescopes into space is very hard.

image NASA’s Spitzer Space Telescope snapped this photo of hundreds of thousands of stars lurking in the Milky Way Galaxy, thanks to its infrared photography equipment. NASA/JPL-Caltech, CC BY

We can build big telescopes on the ground that use lasers and bendable mirrors - bending the mirrors to match the twinkling starlight. This then shows us the whole universe, as if the atmosphere vanished above us!

image Astronomers use lasers to work out how the atmosphere moves, so that they can remove the twinkle from stars they observe. This whole process is called ‘adaptive optics’. G. Hüdepohl/ESO

But what about the planets?

So that’s the story of why stars appear to twinkle in the sky. If you look really carefully, you might have noticed that planets, like Venus and Jupiter, don’t seem to twinkle like the stars around them.

Why is that?

Well, if you look at a star through even the biggest telescope, you still just see a tiny point of light. This light comes through the atmosphere in a tiny beam - that can be easily knocked around.

If you look at the planets through a telescope, you see their disks - they are close enough to us that we can “zoom in”, and see a planet, rather than a point of light. That means that the light from those planets comes through the atmosphere in a much thicker beam than that from a star - and that thicker beam is much harder to knock around.

image Only stars twinkle in the night sky. Planets in our solar system are too close and big for them to twinkle. Venus is the brightest light nearer to the centre. Jupiter is just north-west of Venus. Brocken Inaglory/Wikimedia

As a result, the planets barely flicker, while the stars twinkle like crazy.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

* Email your question to curiouskids@theconversation.edu.au * Tell us on Twitter by tagging @ConversationEDU with the hashtag #curiouskids, or * Tell us on Facebook

image CC BY-ND Please tell us your name, age, and which city you live in. You can send an audio recording of your question too, if you want. Send as many questions as you like! We won’t be able to answer every question but we will do our best.

Authors: Jake Clark, PhD Candidate, University of Southern Queensland

Read more http://theconversation.com/curious-kids-why-do-stars-twinkle-81188

INTERWEBS DIGITAL AGENCY

The Conversation

Politics

Scott Morrison on Credlin

PETA CREDLIN: Thank you for your time tonight, PM I know you've got a lot on your plate. I'll get to the issue of bushfires in just a moment, but I can't let it go unremarked that with Australia Day...

Peta Credlin - avatar Peta Credlin

Scott Morrison interview with Ray Hadley

RAY HADLEY: Prime Minister, good morning.    PRIME MINISTER: G’day Ray.    HADLEY: Jeez you copped a hammering while I was away.   PRIME MINISTER: Goes with the job mate.    HADLEY: Well, yo...

Ray Hadley - avatar Ray Hadley

Immediate small business support for bushfire affected communities

In response to the devastating bushfires, the Morrison Government has today announced a comprehensive suite of measures to immediately support impacted small businesses.    This initial package ...

Scott Morrison - avatar Scott Morrison

Business News

2019 Hottest FinTech Startups Overview

Modern technology is experiencing rapid growth, so many industries expect a so-called revolution, and the financial world is no exception. Over the past ten years, people have witnessed the emergence ...

News Company - avatar News Company

Australians need to look out for this US Crypto-platform

Good news for Aussie sports fans as UssCyber is soon to launch its very own crypto-currency sports trading platform. UssCyber, a blockchain-oriented company based in Florida, is introducing “World S...

News Company - avatar News Company

How to Choose the Right Data Recovery Solution for your Business

In the modern business environment, data is one of the most important commodities. A typical B2C seller, for instance, offering home delivery service cannot deliver the product to the right addres...

News Company - avatar News Company

Travel

The Family Travel Handbook from Lonely Planet

Everything you need to know to take unforgettable trips with your children   Full of practical advice, ideas and inspiration for every type of family, Lonely Planet's The Family Travel Handbook ...

Adam Bennett - avatar Adam Bennett

3 Ideas for a Family-Friendly Holiday to Bali

A family holiday is always an exciting time, but it can often come with its fair share of challenges, especially when trying to keep every member of the family happy. Thankfully, the beautiful islan...

News Company - avatar News Company

The Best Things to Do in Adelaide Hills

Adelaide Hills has long been a relaxing escape for the people of Adelaide and beyond. Its proximity to the capital makes it an accessible destination that feels like you’re miles away from the hustl...

News Company - avatar News Company

ShowPo