Category Archives: Observatories

A feast to the eyes and to the heart: the VLT as seen by a non astronomer

By Meghie Rodrigues

The first thing you notice when you approach the VLT (Very Large Telescope) is its size. No doubt this is ‘big science’ in all senses: the four main telescopes have mirrors measuring 8.2m in diameter and are housed in structures which are as tall as an eight floor building (25 m high) and as heavy as about a hundred Asian elephants (430 tonnes). It brings to mind that the old saying ‘bigger is better’ makes a lot of sense when it comes to optical astronomy – the bigger the mirrors used, the more light you get and the farther you can look into deep space.

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Two of the four main telescopes at the right and one of the auxiliary telescopes at the left

This is what I saw, along with other Brazilian journalists, in getting to Cerro Paranal, a mountain region located in the Atacama desert in northern Chile. The European Southern Observatory (ESO) runs a variety of telescopes in the region and the VLT is the biggest of them.

We were taken to more than 2,600 meters above the sea level in one of the driest places on Earth (lots of sunscreen, drinking water and winter clothing is highly recommended) where rain just falls for about two months a year and where you can see the clouds below your feet, kept from getting too close by the Andes range. Which is a good thing for observations: the lower the humidity in the atmosphere, the lower distortion you get in images – and the further you go from cities or places with artificial light, the darker and better it is to observe the sky. And yes, from the point of view of a Brazilian, nights are terribly cold at that altitude!

Days at Paranal are as bright as nights are dark, and the view of a rich diamond-studded black cloth extended high above your head during nighttime is a feast to the eyes and to the heart.


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Roof of the main telescope #2 (Kueyen) open to get the instrumentation ready for night observation

Named in Mapuche language – Antu (the Sun), Kueyen (the Moon), Melipal (the Southern Cross) and Yepun (Venus) – the telescopes can be used separately, each as a single instrument, or together, as what scientists call a ‘interferometer’. As such, it allows a closer look into many observation questions, including extra-solar planets – or planets outside our solar system –, the formation of stars and planetary systems as well as the surface of stars.

In talking to astronomers at Cerro Paranal, it wasn’t hard to see that ‘impressive’ applies not only to the size of the main telescopes but also to the science that comes out of them. The first image of an extra-solar planet, 2M1207, was one of them. Also, the oldest star we’ve seen in the universe up to now – which is said to be 13,2 billion years old, almost the age of the Universe itself – was found using the telescopes. Evidence of the accelerated expansion of the Universe also drew from many of the VLT observations.


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Mirror of the Kueyen telescope, 8.2m wide

So many hours of past and present observations are made by astronomers who are specialists in the many instruments VLT has – requested by other scientists from a wide range of fields in observational astrophysics spread all over the world. They give away their evenings and nights in a different kind of ‘star parties’: instead of our romantic idea of an astronomer peeping into a telescope in a cold night, they receive tons of data from different ultra-sensitive cameras installed in the telescopes. Barbara has given us an account of her own observations there some time ago and she gives us a great idea of how it all works. 🙂

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Astronomers in action in the VLT control room at the Interferometer console

It was, in the end, quite interesting to be able to see and think about some of the tendencies and routes ‘big science’ is taking in a world where scientific and political cooperation is key. Massive projects like the Thirty Meter Telescope, the Giant Magellan Telescope and ESO’s European Extremely Large Telescope rely on more than agreements between research institutions and universities – they also go for negotiation between governments and their institutions, taking the conversation to the arena of diplomatic relations. Conversation on this level means more solidity for projects, which is important especially when it involves billions of dollars or euros. After all, you can’t do ‘big science’ alone.