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15 Jun 2022

Stargazing delight in the city

Did you know only one fifth of the human population enjoys a dark night sky? And more than 20% of the Earth’s landmass at night is afflicted by a dull yellow glow?

But even in the heart of a major urban centre like Sydney, we can still observe the celestial bodies with the help of a simple telescope.

Speaking to a group of stargazers at the Royal Botanic Garden Sydney, astrophysicist Dr Ángel López Sánchez says that it isn’t just astronomers who should worry about light pollution, but anyone who is concerned about human and planetary health.

“It is not just a problem of the poor astronomers who can’t do their astronomy, no no no, it is pollution that we are putting into our environment," he says.

"And if you don’t want to look at it that way, put it in terms of money, and energy, and CO2 emissions that we are releasing into our cities illuminating the night sky. That is a lot of money that everyone is losing because of light pollution.”

We now know that an excess of light can cause stress, insomnia, fatigue, and anxiety in humans, while other animals suffer even more: sea turtles, birds, frogs, bats, spiders, plankton, moths, and fireflies are all left dazed and confused, their ability to navigate, mate, or pollinate impaired by the bright night sky.

Luckily for amateur astronomers, however, even in the heart of a major urban centre like Sydney, we can still observe the celestial bodies with the help of a simple telescope.

At the astronomy nights of The Calyx, members of the Northern Sydney Astronomical Society are there to provide you with their mirrors, lenses and expertise to help you navigate the heavens.

The thing I love about astronomy is that the sky is open to everybody! I can be a professional astronomer using the largest optical telescopes in the world, but I still love to get my telescope and see how things are working with my own eyes and my own camera.

With at least 100 billion stars in the Milky Way to choose from, you’ll be spoilt for choice. In the southern hemisphere, the Crux (Southern Cross) constellation has a number of wonders: if you point your telescope to the brightest point in the cross, called Acrux, you’ll see two suns revolving each other, and if you look nearby the second brightest star in the cross (Mimosa), you’ll see what astronomer John Herschel described as a “superb piece of fancy jewellery” – the Jewel Box, a cluster of around 100 stars of just 14 million years of age.

But Dr López Sánchez says what you see in the telescope (that is, atoms) makes up less than 5% of the mass-energy in the cosmos. The rest, he says, is composed of some kind of matter that neither emits nor absorbs light – or what scientists call “dark” matter. 

According to some estimates, 25% of this mystery substance is dark matter, and 70% is dark energy – “And that is why astronomy is still so exciting!” says López Sánchez, “There is still plenty more to discover. What we know about the universe is that we know almost nothing about the universe! About 95% of the universe, we do not know what it’s made of.”

Astronomy at The Calyx is being held Tuesday 6 September 6.30 - 9.00pm and Wednesday 2 November 7.00 - 9.30pm. Buy your tickets here.

Visit The Calyx

If you're keen to explore this amazing venue by day, why not check out 'Tideline', presented by Cilla Campbell, the Bathurst Street Printmakers and the Creative Outdoor Group.

Tideline is an imaginative exhibition of works on paper in response to the current ‘Inside the Tide’ exhibition in the Calyx. It's on from June 20  to June 26.

This blog was written by Tim Ginty and has been republished with permission.

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