When science fiction becomes reality

01 February 2018 - 06:00 By Tanya Farber
ExTrA telescopes, situated in Chile, will be used to search for and study Earth-sized planets orbiting red dwarf stars.
ExTrA telescopes, situated in Chile, will be used to search for and study Earth-sized planets orbiting red dwarf stars.
Image: ESO/Petr Horálek

The science behind it may seem simple: if a small insect crosses in front of a light bulb‚ it will obscure some of the light from the bulb and‚ for a brief moment‚ the light will become dimmer and we will be able to spot the insect.

Except in this case‚ we're talking about astronomical events so far away they're in another solar system‚ and it has taken up until now for us to have the technology and right methodology to detect the obscuring of the light with great precision.

To stick with the metaphor: the "light bulbs" are actually what are known as red dwarf stars and the little insects flying across their discs of light are in fact planets.

Now‚ thanks to a novel approach at the European Southern Observatory's (ESO) facility in the north of Chile — called La Silla observatory — a set of three telescopes and other supporting technology will search for Earth-sized planets and then study them more closely‚ eventually bringing us closer to knowing if they might support life.

The new set of telescopes‚ named ExTra‚ are sensitive enough to search for potentially habitable worlds by constantly searching for a dip in brightness from the red dwarf stars. Lead researcher Xavier Bonfils explained why the remote area in Chile was the best suited for this breakthrough research.

“La Silla was selected as the home of the telescopes because of the site’s excellent atmospheric conditions. The kind of light we are observing — near-infrared — is very easily absorbed by Earth’s atmosphere‚ so we required the driest and darkest conditions possible. La Silla is a perfect match to our specifications‚” he said.

So how does it work? The three ExTra telescopes "collect light from the target star and four comparison stars" and that light is then fed through optical fibres into a multi-object spectrograph (an instrument that separates light into a frequency spectrum).

Earth's atmosphere usually disrupts how our eyes see the brightness of distant bodies‚ but the use of the spectrograph increases the precision.

Red dwarf stars can host many Earth-sized planets‚ "making them prime targets for astronomers looking to discover and study distant worlds that could be amenable to life"‚ the ESO said in a statement.

Bonfils is excited for the future: “The study of exoplanets [planets outside our solar system] is bringing what was once science fiction into the world of science fact.”

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