In the traditions of the Wardaman people of northern Australia, the twinkling of the sky represents stars "talking to each other". Torres Strait Islanders use the stars twinkling to predict weather and seasonal changes. This stellar "conversation" is deeply incorporated into the Indigenous knowledge system when it comes to fishing, planting, harvesting and hunting.
This science used for generations by Aboriginal and Torres Strait Islander people is replicated in Western sciences. Today, adaptive optics systems use lasers to create fake, or "guide", stars to measure the atmosphere and correct for its effects.
The Earth's atmosphere affects the light travelling through it. Our telescopes on the ground look at the universe through the atmosphere, and the turbulence in the atmosphere causes our images we see of space to change.
In the era of building giant telescopes to study the furthest and faintest objects in outer space, the atmosphere plays the showstopper role. The bigger the telescope, the bigger the limitation the atmospheric turbulence will pose. This ultimately means a loss of information and sensitivity, and therefore fewer groundbreaking scientific discoveries.
By using "guide" light sources such as natural stars or the aforementioned guide stars (made by firing lasers into the sky) we can fix this.
There are two ways we can do this. We can fire a laser and it will bounce off dust particles in the atmosphere, or we can use a special yellow sodium laser, which will bounce off a layer of sodium in the atmosphere at 90 kilometres, and then back to the ground.
On the telescopes we use, there is a special device called a wavefront sensor. This device measures the changes in the sky nearby the star, galaxy, or other object being observed. The atmospheric turbulence is not perfectly even across the sky, and changes depending on where in the sky the telescope is looking.
Once the turbulence is measured, the wavefront sensor sends the atmosphere information to a control computer, which commands a deformable mirror. The deformable mirror will correct for the atmospheric turbulence and correct the image to what the object actually looks like, leading to better, clearer images.
At the Advanced Instrumentation and Technology Centre at the ANU's Mount Stromlo Observatory, these systems are being built to enable pioneering astronomy using some of the biggest "eyes" in the universe. These creations include the Ground Layer Adaptive Optics system for the Subaru 8.3-metre telescope at Mauna Kea Observatory in Hawaii, a new one for the instrument MAVIS for the VLT 8.2-metre telescope in Chile, and systems for the new 25-metre Giant Magellan Telescope being built in Chile.
Aboriginal and Torres Straight Islander people and adaptive optics happen to listen to the same "star conversation". Let the stars talk, they have a lot to tell, and we have a lot to learn.
- Noelia Martinez is a researcher at the Australian National University's Mt Stromlo Observatory.