Archive for February, 2012

Is there anybody out there?

Posted: February 26, 2012 by Mr Pimentao in Biology, Space
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Forget about little green men, ET or Alien – they don’t exist. Or at least we don’t have any proof that they do. Despite this, the search for extra terrestrial life is now as lively as ever : from the discoveries of planets orbiting other stars in our galaxy to the SETI (Search for Extra Terrestrial Intelligence) project, scientists are scrambling to find a glimpse of life away from our own home planet.

Exoplanets and the Goldilocks principle

Exoplanets are planets that orbit stars other than the Sun. For decades astronomers had suspected that other stars in our galaxy might have planets orbiting them ( just like the Sun has Mercury , Venus, Earth, and so on… ) Like all the other scientific predictions, you can only confirm it if you have enough evidence to back it up. Guess what – for the last ten years or so, astronomers have found evidence that in fact there are planets orbiting stars in our galaxy.

Planet in transit across the star disc: Picture: ESO/L. Calçada

The problem with seeing planets orbiting stars so far away from us is that the brightness of the star outshines the tiny amount of light reflected by the planet. Only very recently , with developments in image processing software and improvements in CCD technology have scientists been able to detect planets. But this doesn’t even mean that we can actually “see” the planets – we can’t , at least not directly. We must look for clues in how the light from these stars reaches us.

One way of telling if a star has planets orbiting it is called the “Planetary transit” method.   Whenever a planet is placed between us and the star, we can detect a small decrease in the brightness of the star. Imagine a mosquito flying in front of a lamp – whenever it flies between us and the lamp, we can see that the lamp seems to get dimmer because the mosquito blocks a tiny bit of its light.  The same happens with a planet that orbits around a far away star. Every so often the planet blocks some of the star’s light and the star appears to have dimmed by a  little amount. Scientists look out for these tiny changes in the brightness of stars and use their data to compare the size of the planet with the size of the star.

This is all fine, there are more planets in the Universe than those we have learnt about in Miss Gileece’s lesson…. My Very Easy Method Just Speeds Up Naming Planets… But is there life living on them? Do they have BBM?

The answer is….. we can’t tell if there is life on any of the exoplanets that were found, let alone whether or not they have BBM. One thing we know is that life as we know it has first appeared in liquid water –  right here on Earth, millions of years ago. So, we can be certain that planets where liquid water exists are more likely to have life.  The planets that obey this condition must be at the right distance from their star for the temperature to be just right for liquid water to exist. Depending on the kind of star , and on the size and composition of the planet, the temperature is just right for liquid water if the planet orbits the star at a range of distances often called “the Goldilocks region”.

This raises the question: how do we know if these exoplanets have liquid water? And if they do have liquid water does that definitely mean that they have some kind of life?  Life on Earth evolved in water , but there are so many variables to take into account that it is currently impossible to prove that there is indeed other life forms in the Universe.

So, if you were expecting a YES or NO answer to the question you may now be disappointed (or not!). All we can say is that most probably there is life somewhere in the Universe, possibly in a planet orbiting one of the hundreds of million stars in our own galaxy, the Milky Way.

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Happy birthday to you, happy birthday to you, happy birthday dear Charles Darwin, happy birthday to you!

Happy Birthday Darwin!

On this day in 1809 Charles Darwin, arguably one of the most important scientists ever, was born in Shropshire. Charles Darwin is famous for his book On the Origin of the Species where he introduced ideas to explain the origin and diversity of all living species via Natural Selection and Evolution. Darwin was interested in most things, and his work as a geologist and naturalist gave him to opportunity to travel around the world on a 5-year voyage aboard the ship HMS Beagle. Keeping careful notes and making copious observations during the expedition, Darwin saw great biodiversity and it allowed to him to begin considering the origin of this. When he returned to England he began to formulate his idea of Natural Selection.

HMS Beagle

What is Natural Selection?

Darwin had noted that nearly all the species he had encountered were perfectly adapted to a variety of different habitats, diets and lifestyles. His visit to the Galapagos Islands (near Ecuador) had allowed him to study a group of birds (now known as Darwin’s Finches). He was amazed at the variety of different beak shapes and sizes, each adapted to a different way of life.

The Galapagos Islands

How did this happen? Natural selection requires three factors. The first is variation (differences) between individuals. The second is competition between organisms (e.g. not enough food to feed every organism) and finally an environmental change.

Darwin postulated that originally a group of finches arrived at the Galapagos islands from mainland Ecuador. There was variation of beak size within this group of finches. Because there were different food sources on the island (seeds, fruit, insects etc) different beak sizes were more suitable for different diets. For example, large beaks would be able to break open seeds that smaller beaks wouldn’t. If there were plentiful seeds, the larger beaked birds would find more food, have more offspring and therefore pass on the genes for the larger beak. This would continue as long as larger beaks gave a survival advantage. Eventually, with successive generations and continued ‘selection’ for a certain feature, the original population of birds diversified into many different species.

Darwin's Finches

Darwin realised that this same process, occuring over millions of years, could explain the diversity of all living (and extinct) species.

The Theory of Evolution has shaped our understanding of diversity, formation of new species and our position in the Tree of Life. So, thanks Darwin, and Happy Birthday!

The Tree of Life

 

On 7th February 48 students from Year 11, (accompanied by Mr Bilton, Miss Vine, Mr Pimentao and Miss Gilleece) travelled to Essex to visit the npower-operated Tilbury Power Station. The students study the generation of electricity as part of their course, so this was an excellent opportunity to see where it all happens. The Tilbury site was originally a coal-fired power station, but this year it switched to using biomass as the fuel source, as part of a programme to be ‘greener’ and depend on renewable sources.

Tilbury Power Station

The biomass used at Tilbury is wood pellets, produced from the sawdust and waste of the Canadian lumber industry, so it’s a good use of a material that would otherwise just be wasted. It also has less impact in terms of CO2 production than coal, because it’s not burning carbon that’s been locked away for millions of years.

Properly kitted out in hard-hats, ear defenders and high-visibility jackets the students were taken on a tour of the power station, at one point standing inside a 65m furnace which reaches temperatures of 1500ºC (luckily for the students it wasn’t on at the time…). The scale of the facility is hard to imagine, but it gives you an appreciation of engineering behind the process.

Safety first - hard-hats and ear defenders!

The process of electrical generation is actually remarkable simple. When the biomass arrives it is crushed and then blasted into the furnace where it burns. The furnace is lined with pipes that contain ultra-pure water. As this water heats up it turns to steam. This high-pressure steam is used to turn turbines (converting heat energy into kinetic energy), and the turbines rotate an electro-magnet within a coil of wire. The movement of a magnet within a coil of wire creates the electrical current (thanks Faraday!) and that’s all there is to it.

Generating electricity - what's happening inside?

The students were also able to study some of the chemistry and biology surrounding the issue of power generation. Using conductivity meters the students recorded how many dissolved ions and minerals were in drinking and filtered water. They then compared it to water that had been through an ion-exchamge resin and were surprised to see that there were no ions left at all. This super-pure water (which actually tasted a little bland) has to be used in the power station to prevent damage to the pipes (picture the inside of your kettle..). The students then had a look at the local water quality by pond-dipping and looking for indicator species; species that tell you how clean the water is by their presence or absence. Having found a variety of insects including Common Backswimmers, Damselfy nymphs and Diving Beetles (and even some fish) everyone was surprised to conclude the water so near a power station was actually good quality and supported a diverse community.

Damselfly nymph - this larval form indicates good water quality

Common Backswimmer - this insect swims upside down

The students had a really good time and certainly learned lots about where their electricity comes from and how best to manage our energy resources so that we can live in a sustainable and ecologically-sensitive way. Many thanks too to the staff at the power station for giving us such an enjoyable day!

Big Schools Birdwatch 2012

Posted: February 1, 2012 by Mr Bilton in Animals, Biology, Field Work
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Last week every member of Year 7 and 8 took part in the RSPB’s ‘Big Schools Bird Watch’ event. Having placed hand-made bird feeders around the school the previous week, students spent a lesson outside, armed only with a pair of binoculars, a pencil and an ID guide, trying to spot some of the common (and more elusive) birds in the school grounds.

Birdwatch 2012 - The school ground support a large variety of different bird species.

It was certainly an eye opener, and the graph shows the variety of different species seen. The students were recording the maximum number of any given type seen at the same name. As you can see, we’re very lucky to have such biodiversity in the school grounds and we’re looking forward to comparing our results when we participate in the event again, next year.

If you’re interested in finding out about birds, have a look at the RSPB site http://www.rspb.org.uk/.