Outer Space. It encompasses distances we can barely fathom, temperature ranges we can hardly comprehend, and shines in wavelengths which we can never see.

Take our Sun, for example, a fairly small star at a mere 1,392,000 km in diameter. Most of us can’t hold that number in our heads – it’s too far outside anything we’ve experienced. We can try to visualise it by comparison to distances that we know – say, the distance between New York and London. That’s 5,500 km, which means it would be around 252 trans-Atlantic flights. Assuming each flight is 7.5 hours then you’ll be spending 78 days in an aeroplane. 78 days’ worth of aeroplane food – now that is a number we can get our heads around.

But it gets even more difficult when we start looking at larger objects. Alpha Centauri, our nearest neighbouring star, is 4.3 lightyears away – converted to kilometres we get 41 followed by twelve zeroes. Twelve! You and your aeroplane food would be dust long before you even came close to your goal, and this is before we start trying to wrap our heads around deeper space objects like supernova remnant Cassiopeia A, a mere 10,000 light years away.

So how do we bring these distances and these objects down to our mortal world of commuter jets and slow-moving traffic? This is where the work of scientific communicators and researchers such as Kimberly Arcand of NASA’s Chandra X-ray Observatory comes in. Her job involves taking arcane data and scientific information and finding the best way to make them understandable for all walks of life.

254 Shades of Grey

When we look out our windows at the world passing by, we see reds, blues, greens, all the colours of the rainbow. But the rainbow we see is a tiny, tiny part of the rainbow we could be seeing, if only we had the ability. Infrared cameras, radar, X-ray telescopes: all of these rely on being able to ‘see’ wavelengths which are invisible to our naked eyes. But once detected, how do we visualise this information? What colour is that radar image or ultraviolet source?

One traditional approach used by scientists has been to ignore the problem entirely, plotting all information on a scale from black (no signal) to white (100% signal) and then dividing everything else into various shades of grey. This is unambiguous, you can easily see how different parts of the image relate to others by examining how bright they are. But it becomes difficult when different images are merged – is this bit of grey part of the first image or the second? It also misses the chance to include important information. We see in colour and are thus skilled at interpreting and understanding multicoloured images (unless levels of colour blindness come into play).

But translating the invisible world into glorious colour brings its own challenges. As Kim comments: ‘There are human biases that are introduced in that translation process. There are many choices that must be made along the pipeline, from cleaning the data and removing artefacts to more aesthetic issues such as mapping colour.’ The way we respond to colour affects our interpretation of the imagery.

Take recent work by her group, in which they surveyed a number people regarding their perceptions of various astronomical images. The information was drawn from data outside the visible spectrum and thus was represented using ‘false-colour’ imagery, in which the colour in the pictures isn’t the same as we would see looking through a pair of binoculars (because of course, we couldn’t see it at all). High-energy regions were marked in blue, low energy in red. This makes perfect sense to an astronomer, because high-energy objects are hotter, and hotter objects are blue. However most of us think of red as being the colour of heat, despite this not being the case. Want to check this? If you were to stick your hand in a candle flame, the blue part of the flame is far hotter than the red… but kids, don’t try this at home!

This mismatch in beliefs means that effectively showing scientific data to nonexpert audiences requires scientists to reflect on some of their standard approaches. What is important is in getting the information across to the audience, not slavishly holding to a single manner of representing it. But most importantly, we also need to explain why these colours were chosen and what they represent.

The vast majority of questions which came up during the survey asked about the colours of the astronomical objects – do they really look like that? Are those colours real? In a world of easy photoshopping and Instagram filters we tend to distrust the images we see, and thus scientists need to be transparent about what they are actually presenting to the world.

Science for Everyone