Access Science: Get involved in a study of light and air pollution

Ireland has some of the least polluted skies in Europe, and not just in terms of air pollution: we also have relatively clean skies when it comes to light pollution – that is, the impact of surface lighting, which spoils our view of the night skies.

We will soon be able to compare our light and air pollution against other countries in a major study prompted by the International Year of Light.

This citizen science initiative involves using your iPhone as a light meter, via an app that can measure the impact of surface lighting, says Prof Martin Leahy, Ireland’s national co-ordinator for the Year of Light.

In a second study, 25,000 participants will be encouraged to use an app that allows iPhones to measure atmospheric pollution levels.

NUI Galway is playing an important role in this European initiative, says Leahy. "We are taking measurements in Ireland near Mace Head to provide baseline data for air and light pollution."

Mace Head has been a centre for atmospheric research for decades, given it can provide measurements of some of the least polluted air anywhere in the EU. It is also an area with low light pollution levels, which can be compared with data being retrieved by citizen scientists across the EU.

The app that will allow measurements of ambient light conditions will be ready soon. People can get in touch with Prof Leahy or the Year of Light website to discover how to participate. The app that will be used to measure air pollution equips smartphones with a spectrometer; the plan is to make 25,000 of these available across the EU.

People will take readings and then email their results back to a centre in the Netherlands. This data will then be compared against readings from Mace Head.

The spectrometer app costs about €30, while the light pollution app will be available at no or very low cost, but the apps will be available on the iOS platform only.

Those interested in participating in these two studies can get in touch with Prof Leahy by emailing info@light2015.ie or martin.leahy@nuigalway.ie

A LEVEL PLAYING FIELD: WHAT DOES THAT EVEN MEAN?

• Question: Considering we live on a sphere, how can we define anything as being level? Level to what? Where do we get our calibration to define level?
• Answer: When we think of something, such as a table, being "level", we might think that if someone leaves a ball on it, then the ball shouldn't roll off. So, when do balls not roll off tables? If the surface of the table is exactly perpendicular to the direction of gravity, then the gravity will pull the ball straight down into the table. However, the ball cannot respond to this pull of gravity by moving down, and so will just stay there. On the other hand, if the surface of the table is not quite perpendicular to gravity, then one end of it will be slightly lower than the other. Gravity will still pull the ball straight down, but now the ball can move a little downwards by moving along the surface of the table towards the lower end. So a surface is level if it is perpendicular to the direction of gravity. The direction of gravity varies; it generally pulls pretty much directly towards the centre of the Earth, so if you were to construct a very large, level surface on the Earth, it would be curved, just like the surface of the Earth itself. Prof Turlough Downes, DCU (in conversation with Claire O'Connell)