Astronomy in the desert!

While in the Atacama Desert we had two awesome experiences where we got our first taste of astronomy.

We took part in a star gazing tour where we did celestial observation. Most of the Tours around San Pedro de Atacama are run by hobbyist astronomers. On our tour we went to the guide’s backyard where he kept his really big personally owned telescopes. An interesting thing about Astronomy tour is that it was done in almost complete darkness.

I have never seen the stars like I saw that night. There were so many stars, and they were so beautiful. We got to see star constellations like the scorpion, belt of Orion and the southern cross (yes I know these can be seen in Australia, but this was a unique opportunity in a low-light environment).

Let me explain how you can tell how old a star is, and why they are different colours.

There are a lot of ways to determine how old a star is. One of the ways is to see what colour it is. New stars are hotter and have a blue appearance whereas older stars that are cooler and that are coming up on the end of their live appear red.

But we got to see stars that I had never seen before. There is this cool star that looks like just one star to the naked eye, but then when you look through a telescope it, hundreds of thousands of stars together – these are called Star Clusters. Our guide said it was like a neighbourhood where all the stars live together. We got to observe a Star Cluster called Jewel Box because there where old and new stars living together. With red, yellow and blue stars all at different life stages.

The Astronomy tour in San Pedro de Atacama had night photos as part of their tour. So that was exciting. View the photos below.

Two days later, we visited the European Southern Observatory (ESO). This was nothing like the tour we did in San Pedro the Atacama. This was a multimillion-dollar facility with massive optical telescopes (VLT – Very Large Telescope) built on top a mountain called Cerro Paranal at 2600 metres. They have four-unit telescopes named Antu (Sun), Kueyen (Moon), Melipal (Southern Cross), and Yepun (Venus, as the Evening Star). The names are all come from Mapudungun, the language of the Mapuche people, an Indigenous group from southern Chile and Argentina

We got to walk around in one of the telescopes and got to learn a little about how they work. They are building an even bigger telescope on a nearby mountain (Cerro Armazones), imaginatively called the Extremely Large Telescope (ELT). This is still under construction. When it is complete, it will be the world's largest optical and near-infrared telescope with a 32 metre mirror, making it larger than all other professional optical telescopes in world combined. Its first observations with scientific instruments are expected to be delivered in December 2030. But the ELT is set to make its first test observations in early 2029.

Now I am going to try and explain the difference in size between the telescope in the Guy’s backyard in San Pedro; the VLT telescopes at Cerro Paranal; and the ELT they are currently building at Cerro Armazones. The curved mirrors in telescopes are used to collect and focus light on to a focal point in a basic telescope where the eye piece is. The larger the mirror is, the more light it collects.

The backyard telescopes in San Pedro had mirrors with a diameter of about 30 cm, roughly the size of a dinner plate. The four VLTs at Cerro Paranal each have 8 metre diameter mirrors, about the size of a large household living room, and is approximately 700 times larger than the dinner plate. When finished, the ELT will have a mirror diameter of approximately 39 metres, roughly the size of two basketball courts, and is 20 times larger than each of the VLTs (and is about 14,000 times larger than the backyard dinner plate). Just imagine the size of the machinery that will pivot this telescope!

[Now those of you who know me well, will be well aware that I am very dyslexic. I want you to glance back at the previous paragraph, and note my correct spelling of ‘metre’ with an ‘re’, and ‘diameter’ with an ‘er’. Just imagine how hard my dyslexic brain must have to work to get that right – just about as impressive as the ELT machinery I think! 😉]  

Next blog will be about me doing some amateur Astrophotography. I can’t wait!!