The accidental scientist

    Discovered in 1862, 109P/Swift-Tuttle is a big comet with a 26 km diameter, a period of 133 years, last seen around 1992. When a comet gets reasonably close the the Sun (like within Mars or the Earth orbit), the solar wind rips out of it all sorts of debris, mainly ice crystals and dust. This is what the comet’s tail, aka its coma, is made of. If and when the Earth gets close to where the comet’s tail has been, some of these bits and pieces get into the upper atmosphere at high speed, get vaporised and voilà, you get a meteor shower. There is one going on right now, courtesy of Swift-Tuttle. If you are a reasonably motivated early bird, you can have a look at it. It is called the Perseids meteor shower. In theory it peaks between August 9 and 13 but in my humble opinion it will be pretty low on the horizon by then. So you may as well have a go, say, from Saturday 31 and the following few days, between 4 and 5:30 am. Pick a spot away from city lights and with a good

      Last week I had a conversation with Mike about the magnetic poles. I explained to him that the poles tend to go walkabout. The North magnetic pole moves from North Canada towards Siberia at about 55 – 60 kilometres per year. Then Mike asked: is there a link between the North and South magnetic poles positions? No but yes. On the “no” side it can be said that over a period of time one pole can be relatively quiet while the other one runs. On the “yes” side the poles are a manifestation of the Earth Magnetic Field, so the cause of their existence and movements is the same. Many years ago scientists – including Einstein – thought that the totality of the Earth formed a permanent magnet. But since then it was observed that the Earth magnetic field force varied and that its polarity has changed many times in the distant path. A permanent magnet can lose strength over time, but it can’t change polarity. You need something like an electromagnet. And sure enough the Earth o

   In 2000 I spent a year on Macquarie Island doing science stuff. One of the projects we ran was the collection of plastic bits on Sandell Bay, a 2km beach located on the Island West coast. This was done every month. Not really to clean the beach, but to analyse the stuff, figure out where it came from and get a better understanding of the Southern Ocean sea currents. Anyway, collecting about 3 full garbage bags of plastic bits every month on such a remote location is a bit scary, isn’t it? Scary but not so surprising considering that nowadays at least 8 million tons of the stuff end up in the oceans every year. That’s about a garbage truck per minute. A good proportion of this is wrapping sheets. I mean the stuff around hay bales, for example, and just about anything produced by humans. Food wrap is part of that. It is very bad for sea creatures and for us as well: two major reports last year linked 175 compounds to health problems connected to cancers, fertility and fetal developm

  Today, let’s calculate the surface temperature of a star. Physicists like to use the Kelvin temperature because it is convenient. Just imagine a black rock in the middle of nowhere in the universe. It’s very cold because nothing warms it up. So we say it’s at 0 degrees Kelvin. 0°K! In the more familiar Celsius scale, it would be -273°C. That black rock at 0°K does not emit any radiation. But if we warm it up, it will start to emit some weak infrared light. If we heat it hard, it will glow red, then yellow, then white… Now let’s look at the light. It is an electromagnetic wave, and its wavelength defines its colour. The wavelength is expressed in nanometers. FYI 1 nm is 1/1000th of a micron. Visible light ranges from 400nm (deep red) to 700nm (violet). Physicists found out that the light spectrum emitted by a black body has always the same shape. As the black body gets hotter, the peak of the spectrum curve shifts towards the short wavelengths. At 4,000°K, it loo