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Identification

2 Posts tagged with the angela_marmont_centre tag
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In the last few days you may have been lucky enough to see a shooting star as one of the year's biggest meteor showers was displayed in the skies over Britain. But does a meteor ever become a meteorite? And how do you know if you have found one? Well in this blog I will tell you a little more about meteors and meteorites,  what to do if you think you have found one, and how to find out more at Meteorites Day 2012, a special event at the Museum on 2 September.

 

Over the weekend from the 11 to 15 August the UK was treated to the height of a meteor shower recognised as one of the best and most reliable meteor showers in the northern hemisphere. The Perseid meteor shower happens every year between late July and mid August and at its peak can produce tens of meteors an hour.

 

Originating from the debris stream left by the comet Swift-Tuttle as it orbits the sun, the Perseids are so called because they often appear to come from the constellation Perseus - but as the number of meteors increases they can be seen all across the night sky.

 

You may think that this event would lead to an increase in meteorite discoveries that are reported to the Identification Service here at the Museum, but meteors are formed from very small particles of matter ejected from the comet, that burn up completely in the atmosphere. This means that if you see a meteor you are unlikely to find a resultant meteorite.

 

2012-0402 Iron Meteorite Tanzania (UNK)1.jpgA meteorite discovery from Tanzania

 

But what if you do think you have found a meteorite - what can you do about it? Well before you jump to conclusions there are a few simple tests you can do on your possible meteorite.

 

STEP ONE: Test to see if your discovery is magnetic

 

All meteorites have some degree of magnetism; even the stony meteorites have flecks of iron and nickel mixture throughout the rock that distinguishes them from terrestrial rocks. You should be able to detect the magnetism with an ordinary fridge magnet, so if your object is not magnetic at all - then it is most likely not a meteorite.

 

P1070568.JPGTest your object with a fridge magnet

 

STEP TWO: Check the density of your discovery

 

Meteorites, especially iron meteorites, tend to be far more dense than some of the more commonly mistaken terrestrial rocks, so if your specimen is light in your hand when you pick it up, then again it is unlikely to be a meteorite.

 

P1070574.JPGYour object should be heavy for it's size

 

STEP THREE: Look at the surface of your discovery

 

Meteorites are characterised by something called a fusion crust - when the meteorite comes through the atmosphere the intense heat of entry causes the surface of the meteorite to melt. So if you can see cracks and bubbles or even other bits of rock or mineral stuck to the outside of your discovery, then once again, it is unlikely to be a meteorite.

 

P1070575.JPGThe surface of your object should be smooth with no bubbles (right)

 

So what do you do if you have done these three tests and all three suggest that you have found a meteorite? Then bring it in to the Museum! On Sunday the 2nd of September the Museum are holding a 'Meteorites Amnesty' with members of our Earth Sciences department on hand and some genuine meteorites you can touch and compare against your own discoveries.

 

There will also be talks and activities throughout the day all about meteorites. However, if you miss this event, don't worry. Just send us a photo at the Identification Service email (ias2@nhm.ac.uk) or bring your specimen in on another day and we will let you know if you have a meteorite or a meteor-wrong!

 

Find out more about the Meteorites Day special event at the Museum

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Over the last week we've all enjoyed having Nicholas and Olivia with us on work experience in the Angela Marmont Centre, and as one result of their work I've now got loads of great specimen photographs for future blogs, so watch this space! If you fancy doing work experience or maybe volunteeing at the museum, you can find out all about it on our website: http://www.nhm.ac.uk/about-us/jobs-volunteering-internships/index.html So thank you to Olivia and Nicholas for your work and now it's over to you:

 

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We have been lucky enough to work behind the scenes in the Angela Marmont Centre with the UK Biodiversity Team as part of our work experience. Working in the centre has been wonderful for both of us, not only in the fascinating people that we have met but also in the wide range of activities and tasks we have been able to participate in.

 

On arrival we were shown round the collections and were astonished by the sheer volume of specimens in the archives. We were also thrown into several meetings which were lucky to be able to attend and learnt a lot about how the museum functions, along with scientists time keeping abilities… they tend to get caught up in intellectual discussions.

 

Throughout the rest of the week we had many other opportunities to get involved. In the laboratories we extracted plant DNA and analysed along with a tour of the lab, only witnessing a fraction of their hugely impressive facilities and machines. We undertook several outdoor activities including surveys in the wildlife garden for the OPAL Project and enjoyed being a part of the Nature Live show.

 

We were given a hard task of pinning insects and bugs. The specimens were quite old and brittle so our attempts seemed futile as bits of leg and antenna flew across the room. The reason for attempting this was so that the insects looked more alive when it came to setting them in resin for demonstration purposes.

 

Throughout our week numerous artefacts and creepy crawlies were sent or brought in for identification. We were able to witness and taken part, from beginning to end on the process. For us the most interesting was a fossil brought in by a small boy. To the untrained eye it looked remarkably like stacked starfish, however within seconds the expert Luanne identified it as a stem of a sea lily which lived around 200 million years ago in the Jurassic period.

 

Perhaps how we spent most of our time was taking photographs of some of the bug and fossil specimens brought in and making sure they had a number for the ease of the system here in the AMC. Of course whilst doing this we saw and photographed some amazing things. There were fascinating and beautiful fossils and minerals, among which was a mammoth tooth trawled in by a fisherman in the North Sea, a necklace made of teeth and tusks and some stone tools found in the Niger.

 

This is part of the intriguing reply to the person who brought in the stone tools below;

Photos for sorting - Olivia and Nicholas 242.jpg

I’ve had a look at the stone tools that you left in the museum. They are all ground and polished stone axeheads apart from one which is roughly fractured stone [...] I believe that ground stone tools first became important in the Neolithic period, which began around 12 000 years ago. [...] However, this does not mean that these specimens are prehistoric in age at all, as ground stone tools are still quite commonly made around the world, both as tourist objects and as working tools for some groups.’

 

Finally on our last day, in our final hours, we were privileged enough to be shown some of the amazing historical collection, dating as far back as the sixteen hundreds. Sloane was amongst them and we were able to witness his great plant collections, which contain drawings and the first specimens brought back from Jamaica, China and, at the time many other remote unexplored countries of the world. It was very unique experienced and we feel privileged to be among the few who have gained an insight into the histories of natural science and art.

 

Overall it has been a marvellous week filled with variety and no hour was the same, we only wish it was possible to stay longer.