This is what the night sky looks like without light pollution

Winter is the best if coldest time to look up and see the awesomeness of the Southern sky. because as we look up we are looking straight into the centre of the Milky Way.

And this Sunday night is the longest night of the year in the Southern Hemisphere coinciding with the New Moon making it perfect for counting the stars in the Southern Cross.

And if you will do so you can contribute to a world record attempt to map light pollution across Australia.

Whether or not you get to see full beauty of the Milky Way — or even the Southern Cross — depends upon where you live unfortunately. Light pollution can make it difficult to see the stars at night let alone the Milky Way or even the 5 main stars of the Cross that we see on our flag.

The points of light in this image captured over a series of nine days include light from cities and towns, mining sites, fishing boats and gas flares as well as natural sources of light such as bushfires.(Supplied: NASA Earth Observatory/NOAA NGDC)

Light pollution is caused by three different factors.

Firstly, light shining upward can bounce off clouds and molecules in the atmosphere. This is where light is shining upward which happens in about 30% of urban lighting.

Secondly you have glare which is where a bright light is directly in your field of vision, your iris closes down to protect your eye, so again, you can’t see the stars.

And finally, you have reflection which occurs proportion not from just directly the lights themselves, but the reflection of whatever it is the light is trying to illuminate. So reflection of concrete or light coloured surfaces.

The amount of light pollution you experience can vary from night to night — it will be greater if there is cloud in the sky — from suburb to suburb, even within your backyard.

Counting stars in the Southern Cross for this weekend’s world record attempt is much easier.

At this time of year the Southern Cross lies directly above your head between 7 and 8pm (or slightly closer to the horizon if you are in the Top End) with the longest line of the cross pointing directly south.

All you need to do is count how many stars you can see using just your eyes and compare to the images on the website.

You can also note cloud conditions and nearby light sources and don’t let any cloud cover — even rain — put you off as your observations are still important.

The lesson is designed to take 30 minutes and you are encouraged not to rush as, if you’re not engaged for 30 minutes, it won’t count towards the world record. So join me for an online talk and discussion as we work together to be a part of the solution and a part of a World Record Attempt.

The GUINNESS WORLD RECORDS attempt starts from 1pm AEST on Sunday 21 June 2020 and follows night fall around the world. All the submissions will be added to the international database of Globe at Night and participants from across the planet are welcome to take part.

Then after 8pm we will go outside and compare our view of the Southern Cross with the maps on the website and enter our data and hopefully set the World Record but more importantly help build a baseline on light pollution in Australia.

You do need to register on the website: World Record Light

The Australasian Dark Sky Alliance is asking people to join them this Sunday on Australia’s longest night to help researchers create a map of Australia’s darkest skies, and learn about light pollution and its effect on people, animals, and astronomy.

“Together, our observations will map how light pollution varies across Australia’s cities and regions, and make a GUINNESS WORLD RECORDS™ attempt for ‘Most users to take an online environmental sustainability lesson in 24 hours’,” says Marnie Ogg, ADSA’s CEO and founder.

Rain, hail or clear skies, we need everyone to log on and be a part of the online lesson.