The Hobart

Why Do City Lights And Stars Twinkle?

by Stephanie Williams
Why Do City Lights And Stars Twinkle?

Words: Stephanie Williams

Image: Pierre Destribats

Have you ever wondered why city lights sparkle in the distance? Or why the stars pulse in the night sky?

If it’s a clear dark night, you can see thousands of stars that look like they’re pulsating and changing in their brightness. You might be surprised to know that most stars actually shine with a steady light – it’s other factors that cause the sparkle on the way to our eyes.

When you look up, you’re not looking into blank space – you’re looking into the atmosphere. It’s the movement of air (or turbulence) in the atmosphere of Earth that causes the starlight to go a little rogue. Hot and cold air gets in the way and bounces the light around as it travels from the star in the distance through the atmosphere and down to us on the ground. Some of that light reaches us directly and some of it gets bent along the way. Because of that bendiness, our eyes perceive it as twinkling.

Stars that are closer to the horizon appear to twinkle more than other stars higher in the night sky – there’s a lot more atmosphere between you and a star that’s high up. Large astronomical objects closer to Earth, like the moon and other planets, don’t seem to twinkle because there’s not as much atmosphere between us and them.

Twinkling, or scintillation, also plays a role in predicting the weather, with twinkling illustrating how winds are moving. On really rough nights in the atmosphere, stars can appear to even jump around, which is a frustration for astronomers. Astronomers try to overcome the twinkling by using adaptive optics, in which many small mirrors on the scope adjust constantly to allow for the atmospheric disturbances. The pros can also use telescopes orbiting Earth above the atmosphere to avoid the problems caused by turbulence.

City lights work on the same theory. The city lights are distorted by twinklifying gasses depending on the temperature, atmospheric densities and moisture (like rain or humidity) in the area. Some city lights don’t twinkle at all in places that have very low atmospheric disturbances and other cities are known for their pretty sparkling lights. Hobart tends to put in a good showing.

So next time you’re out at night look up and see if you can predict what’s happening in the atmosphere.

Love this

Comment

Your email address will not be published. Required fields are marked *

Close
Exploring Tassie These Winter School Holidays
We know that staying indoors with the family isn’t always fun. And while it’s obviously cold outside, you’re only a puffer jacket and beanie away from being comfortable and ready to explore. There’s lots of family fun to be had in all sorts of weird and wonderful places across the state these school holidays.
Sand Surfing on the Peninsula
The half-day walk to Crescent Beach in the Tasman National Park offers so much- including epic sand dunes for surfing and incredible views.
27 Hobart Friends Get Snipping For One Off Wine
The borders were declared shut in Tasmania on the 30th of March, 2020; the first stare to do so amid the COVID- 19 pandemic and hard lockdown of Hobart followed.
Danphe Nepalese and Indian Food + Peppermint Bay Bar and Bistro
Nepalese food is a comfort in our house. Having spent much time trekking and mountain climbing in Nepal as a younger man, Nepalese food is something I always love to go back to.
That’s DR Hannah Gadsby To You
From Smithton to Netflix and the Emmys stage, Tasmanian stand up comic Hannah Gadsby has forged an unlikely path. Following on from the massive success of her shows Nanette and Douglas, Hannah brings her new show Body of Work to Hobart this month.
PODCAST: Incat founder Robert Clifford on why electric boats are the future
Robert Clifford is the founder of Incat, a Hobart company building fast ferries for the world. Always looking to future opportunities, he has identified where Hobart sits in the next wave of transportation. For more of this interview listen to The Hobart Magazine podcast.
Is Tourism Ready For More Forestry Wars?
Tasmanian forests are special. They’re home to centuries-old trees, including the tallest flowering trees on the planet, and support unique native species. Yet not everyone agrees on how these forests should be managed.
Hobart Chefs: When The Obsession Becomes Real
Tasmania’s brand as a foodie haven is cemented. But within the local hospitality industry there are those who love to use local produce...and those who are next-level obsessed with it. We spoke to a bunch of Hobart chefs who are top of the game when it comes to fostering relationships with local farmers and growers.
Did You Know Australia’s First Female Doctor Was Hobartian?
Tasmania, despite its small size and population in comparison to the mainland, has produced more than its proportionally predicted percentage of significant figures and heroes of Australian history. 
Return Travellers Adding Pressure to Hobart Housing
For all of us 2020 was a year like no other, punctuated by rapid change and plenty of new challenges. For vulnerable people in Tasmania, including people facing homelessness, those on low incomes and those facing increasingly higher rents, it was very challenging. We are seeing a growing demand for homes in Tassie from international travellers returning home, people moving for work and others seeking the lifestyle that our Apple Isle has to offer.
Magazine
AboutContributeAdvertiseNewsletter Sign UpContact
November 2021

Stay up to date with everything happening at the Hobart Magazine.

Thank you to Luke Brokensha for mobilising his friends and local residents recently to host two rubbish clean ups along the Hobart Rivulet after heavy rains.
The warm weather returns...hello summer.
Need a laugh? Check out @theinspiredunemployed feed on Instagram.
Moto Vecchia Cafe in Bellerive and Czegs Cafe in Richmond have joined the Clarence City Council dementia program, creating dementia-friendly spaces for all patrons.
It’s hard to believe it’s not standard practice to have a working phone in every aged care room - shared phones make private conversations impossible and increase the risk of spreading COVID-19.
Tacks on the tracks. Mountain bikers beware of tacks being left on certain tracks on the mountain.
Just when you think your cousins are alright. NZ Opposition Leader Judith Collins took aim at Tassie during her recent (unsuccessful) campaign, calling us Australia’s “poor cousin.” She also seems worried about us nabbing tech businesses, “It’s a lovely part of the world but do you necessarily want to go there with your high- tech business? Possibly not,” she said. We beg to differ!