Satellites have a huge variety of uses, from communications and navigation, to weather and other scientific purposes. We have even put quite a few telescopes up in space.
You may be wondering why on Earth we'd go to all the effort of putting telescopes in space when we have perfectly useful telescopes on the ground. Well, it all has to do with the type of science you want to do.
As interesting as the weather is, it can create some issues when you try to observe things in the sky.
This could be cloud blocking the night sky, or brilliant sunshine hiding your stars during the day.
Depending on the kind of light you want to look at, it might be blocked by the atmosphere, which happens for ultraviolet or some parts of the infrared. This is why telescopes like Hubble are in space.
The stunning pictures you often see from Hubble are possible because it is in space. It can see more types of light than we can from the ground and doesn't have to compete with any impact that the atmosphere might have.
These space telescopes are crucial for broadening our understanding of what is out there, and allow us to do things that aren't possible from the ground.
However, we can also look the other way and look back at the Earth. This is called Earth observation.
You might have heard of the Pale Blue Dot image, taken when Voyager looked back at Earth as it was moving through the outer Solar System in 1990.
Luckily, Earth observation has changed a bit since then.
Places like Geoscience Australia use observations from American and European satellites, going back over 30 years, to monitor changes to the landscape. These satellites make various passes over Earth and record data all over the world. Using the images from these satellites and the years of data we have, we can see changes like floods, changing coastlines, droughts and the health of vegetation - all from space! You can even try this out for yourself using the government-run website NationalMap, where you can see changes over time in your area of interest.
But how can you see a satellite? The good news is you can see them with the naked eye. They are slower than meteors (shooting stars) and usually move at a constant speed across the sky. They look like a star moving slowly, and don't flash like a plane. Usually within three or so hours after sunset is a good time to have a look, since they reflect sunlight. You might also need a dark sky, so it might be something to have a look at when you are away from street lights.
As part of National Science Week, one of the activities organised for the ACT is to have a satellite selfie taken using satellites from the company Maxar.
There will be three passes of the Maxar satellites over the ACT over the course of the week, so get yourself outside to wave hello! Details at: inspiringtheact.org.au/satellite-selfie.
- Eloise Birchall is a PhD student at the Research School of Astronomy and Astrophysics at the Australian National University and an Earth observation data scientist at Geoscience Australia.