People across the country are being enlisted to look at specific constellations, to understand and map the levels of light pollution in cities and regions.

"The activity determines what layer of light pollution people are looking through to see the Southern Cross, and that gives us an on-the-ground map of what's happening with light pollution," Australasian Dark Sky Alliance CEO Marnie Ogg told AAP.

Observers will record their findings in an international online database.

Data about light pollution in the southern hemisphere is currently dwarfed by the amount of data collected in the northern hemisphere

"Up until April, we virtually had no real sources of scientific data in the southern hemisphere for light pollution," Ms Ogg said.

Scientists hope the activity will lift the lid on the effects of light pollution in Australia and inform people about the disruption it causes to humans and animals.

"Nocturnal animals are suffering because they never really get the darkness they need. Insects and spiders are completely changing their patterns and even perfunctory systems such as pollination are being dramatically changed," Ms Ogg said.

Research suggests artificial lights have negative health effects on humans, causing sleep disruption and an increased risk of developing certain diseases and cancers.

"Melatonin cycles are being disrupted and our bodies become unaware if it's day time or night time."

"This is something that you can make a difference with immediately. Light pollution can actually be solved immediately by turning off your lights, and those changes can be global," Ms Ogg said.

The study will also look at the effects of COVID-19 lockdowns on heavily light-polluted places like big capital cities with lots of housing developments.

"With less activity happening around the COVID-19 lockdowns and quarantine, I've certainly noticed that the stars seem to be a bit clearer," UNSW Astrophysicist Kirsten Banks told AAP.

"Wherever you are, you'll be able to see at least a few hundred stars. Even in Sydney and Melbourne, you can still see some of the brightest stars in the night sky," she said.

Organisers says the winter solstice event will also be an attempt to break the world record for 'Most users to take an online environmental sustainability lesson in 24 hours' on the night.

Australian Associated Press