The Copernican

Your chance to be an astronomer

The universe is an immensely vast space. The observable universe, which consists of all the things that can be observed from Earth in the present day, alone is about 93 billion light years, i.e. 0.8 trillion trillion km, across. Looking into this distance requires very powerful telescopes, some of which have to be launched into orbit to eliminate interference by our atmosphere.

These telescopes collect the light coming in different directions, and let us see what exists so far away and how.

Sometimes, the incoming light is so weak that the telescope’s lenses and sensors have to be made very strong and sensitive, by using better electronics and ultra-cold temperatures to prevent thermal disturbances. Thus, the farther we want to see into the universe, the more we must spend.

Not always, however, because nature has a solution in the form of gravitational lenses. These are very heavy objects in the universe – such as black holes or giant galaxies – whose gravitational pull is strong enough to bend light around them. While many such lenses have been spotted, research has shown that the human brain is better equipped than programmed computers to look for these objects. So, enter Space Warps.

Space Warps

The >Space Warps project, led by multiple universities around the world, to let anyone with access to a browser and an internet connection participate in the hunt for gravitational lenses. It was launched on May 8, 2013, and is aimed at astronomy enthusiasts who “can partake in the discovery of these magnificent lenses,” as the American Astronomical Society said in a statement.

The first sets of images open to scanning by users are from the Canada-France-Hawaii Telescope (CFHT) >Legacy Survey. “Even if individual visitors spend a few minutes glancing over 40 or so images each, that’s really helpful to our research – we only need a handful of people to spot something in an image for us to say that it’s worth investigating,” said Dr. Aprajita Verma, co-leader of the project from the University of Oxford.

First-timers on the site are shown examples of what gravitational lenses would look like. Guided by features from these images, Space Warps then displays photographs from the CFHT survey that could contain a lens. To further minimise mistakes, examples of false positives are also given.

Why you should look for a gravitational lens

Imagine a tennis ball: light that passes around the ball will do in straight lines because the ball’s pull is negligibly weak. But if the ball were a black hole, the light rays’ paths will bend around the black hole’s surface (as long as they’re at a sufficient distance to prevent being sucked in).

When light bends around such an object, the observer – the human eye or a telescope lens – will see an apparent image of the light’s source. For instance, if a telescope, a black hole, and a star are in a straight line and in that order, then light from the star will bend around the black before reaching us, throwing up a mirage of the star around the black hole.

If the star were, say, 13 billion light years away from us, its light would have weakened considerably before reaching us. However, the black hole in between would have assisted in creating an apparently closer image of the star, i.e. the mirage, letting us study it without having to boost up our telescopes.

These objects, the gravitational lenses, are nature’s telescopes. They’re very rare, too, and of particular importance to us if they lie in the line of sight of another distant object we want to study. Incidentally, based on how much the lenses bend light, astronomers can also calculate how strong their gravitational pulls are and, therefore, how much they weigh.

There are many telescopes in the world looking just for these lenses. One of them is the CFHT, which has been snapping images of the sky that are stored and processed by computers built to look for lenses. Overall, the Space Warps project is a fantastic learning experience: it teaches you how the universe works and how astronomers gather information and produce discoveries, and places you – a Citizen Scientist – on the verge of important ones of your own.

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Printable version | Oct 26, 2021 5:01:17 PM |

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