This year marks a monumental shift in human history when more than half the people on Earth are expected to be living in cities. Because of the ambient light of urban landscapes, many city dwellers have never seen a sky full of stars.

Over the past two weeks, my students have been involved with an international effort to map light pollution. The GLOBE at Night Campaign ran this year from 25 February - 8 March. Last year over 8,491 observations were reported, My students contributing about 25 to the database.

This is a picture we took and image processed with GIMP to enhance the image, identify the red skyline and ugly light pollution from the city of Melbourne, 30 km away. We used Google Earth to determine our Lat Long and geotag the images.

Our school is also getting behind Earth Hour. As a colleague has suggested, perhaps the students could compare the stars seen during Earth Hour 2008 (8pm March 29th) and then compare them 24 hours later? We are trying to figure out how to turn down some of the waste lighting from our school during 29 March and convincing some nearby factories to do the same. Two of my students even found a school security light that had rotated on its axis and was pointing upwards. Tricky as it is in the middle of our first term break. At least the NSW government is providing some incentive Earth Hour funding.

This picture is my first attempt at using the foreground selection tool that comes with Gimp version 2.4

This old orange carrot was just sitting on a school desk that you can see in a previous blog entry and the image was isolated from the background using this tool.

Very cool and crunchy too. :-)

Here is a screenshot of the graphics software Gimp version 2.4 This is a powerful software package with many cool features including new icon theme, scalable brushes, revised selection tools, new color menu, full-screen editing, new crop tool, improved printing, red eye removal, perspective clone and lens distortion tools.

Not only are there flavours of Gimp that run on just about any computer operating system, because the software is FLOSS it can be freely downloaded and used by my  students and colleagues. There is even a  variant called GIMP Portable that can run on a USB drive or another called Gimpshop that changes the interface to something resembling Adobe Photoshop,

Gimp has attracted some criticism (perhaps unfairly) because of its user interface. As Donna once pointed out to me, the right mouse button is your friend in the default Gimp interface and will bring up many of the functions needed.

Once users get become familiar with the interface of one software package they are often reluctant to adapt or master the interface of another. When the general concepts of layers, filters and functions are so similar, it is sad to see them stuck on this learning curve. None of the major graphics software packages really work 'out of the box' without some external help with lessons or tutorials. In the context of a secondary school, arguments about 'industrial software standards' are phony and undignified. It all comes down to your personal taste, needs, funding and experience.

As a lite user, it does exactly what I need from a software graphics package with the basic functions just a click away. Money saved is money in my pocket.