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Podcast TranscriptThe Naked Scientists: Science Radio & Science Podcasts |
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Scientists crack Peanut Allergy Problem
Researchers have successfully treated four individuals with peanut allergies using an approach called oral immuno-therapy.
Writing in the journal Allergy, lead author Dr Andy Clark, who is based at Addenbrooke's Hospital in Cambridge, explains how he and his team recruited four boys aged between nine and thirteen with established allergic reactions to peanuts. Blood tests on the children confirmed the presence of ciculating peanut antibodies, and injecting small amounts of peanut protein into the skin provoked signs of inflammation, proving that the boys were reacting to the nuts.
The children were then given daily doses of peanut flour containg the nut protein to eat every day. The starting doses were very small at just 5mg per day but this was doubled every two weeks until the participants were eating 800mg per day, equivalent to about four peanuts.
After a further six weeks at this top dose the volunteers were then "challenged" with twelve whole peanuts, which they were all able to consume without ill effects. During the study the volunteers were equipped with antihistamines and adrenaline syringes in case of anaphylaxis, but apart from mild reactions the process was well tolerated by the subjects who have now been prescribed a daily peanut ration of five nuts per day to ensure their new-found "tolerance" for the food is maintained.
Both the patients and the researchers are delighted with the results but they do caution that it's a small trial and not something that should be undertaken outside of a properly monitored medical setting.
"Don't try this at home," says Clark.
22nd Feb 2009
Cervical cancer rates higher in poorer areas
Cervical cancer is in the news here in the UK as reality TV star Jade Goody has been diagnosed with the diease. And this week researchers at King's College London have published a paper showing that rates of cervical cancer are higher in poorer areas than in richer ones - results hat have important implications for targeting cancer awareness and screening campaigns.
Led by Dr Laura Currin, the researchers analysed data from over 2,200 women diagnosed with cervical cancer between 2001 and 2005 in London, Kent, Surrey and Sussex. They then looked for any patterns linking the disease to social deprivation, and related factors such as smoking, teen pregnancy and cervical screening.
The team found that the rates of cervical cancer varied dramatically across South-East England, and in some neighbouring areas there was up to a three-fold difference in rates, with much higher rates of cervical cancer in poorer areas.
There's a number of reasons for this. Firstly, smoking is linked to increased risk of cervical cancer, and rates of smoking are higher in poorer areas than richer ones. Also, we know that women in poorer areas are less likely to take up cervical screening, which saves thousands of lives every year in the UK. Last year alone, hundreds of thousands of women across the country failed to take up their invitation for screening.
The key thing about cervical cancer is that it's a highly preventable disease. The national screening programme of smear tests picks up pre-cancerous changes, so women can be treated before the disease has even developed. These new results tell us that healthcare providers and health campaigners need to focus their efforts more firmly on reaching women in poorer areas of the UK, encouraging them to be aware of symptoms such as bleeding between periods, and going for screening when they are invited.
And although Jade's story is a terrible personal tragedy for her and her family - as it is for any family affected by cancer - she has done a lot to raise awareness of cervical cancer among younger women. Cancer Research UK have seen a big jump in the number of people seeking information about cervical cancer symptoms and screening on their CancerHelp UK website and Science Update Blog. Hopefully we'll see a jump in the number of women going for screening, particularly from poorer areas, which could lead to lives saved in the future.
References | |||||
| - L Currin et al (2009) BMC Public Health (in press) | |||||
22nd Feb 2009
New way to battle opioid withdrawl
Scientists have found a drug which is highly effective at combating the symptoms of opioid withdrawal. 
Writing in the Journal of Pharmacogenetics and Genomics, Stanford University researcher Larry Chu and his colleagues made the discovery by studying how 18 different strains of morphine-addicted laboratory mice coped with going cold turkey. When opioid-accustomed mice are given a drug called naloxone, which blocks the effects of opiates, they jump up and down, and strains that show more jumping behaviour seem to be worse withdrawers than animals that jump very little.
To find out why the team compared the DNA sequences of animals that jumped the most with the mouse strains that jumped the least. The team were gratified to find a DNA hotspot in a gene called Htr3a, which is a brain receptor for the transmitter substance and chemical feel-good factor serotonin, also known as 5HT. The strains of animals with the worst withdrawl effects seemed to have a different form of this 5HT3 receptor than the animals with fewer side effects, prompting the team to speculate that 5HT might be linked to at least some of the classical symptoms associated with drug withdrawal.
To find out they gave the mice doses of the drug ondansetron, which blocks 5HT3 receptors and is used to prevent nausea in patients undergoing chemotherapy. Administration of the drug to the withdrawing mice produced a dramatic improvement, and since the drug is already licensed for human use, the team conducted a simple trial on humans volunteers. Similar to the mice, 8 subjects received either ondansetron or a placebo before being treated with morphine and then put into withdrawal using naloxone.
Predictably, those given ondansetron first reported far fewer unpleasant withdrawal effects compared with their placebo-treated counterparts. The researchers are pleased with the result, but caution that the drug isn't a panacea and addiction is a hard nut to crack. At the same time, the findings offer encouragement that other receptor-systems responsible for the effects of physical addiction, which compel addicts to continue using drugs, will be found so that more effective treatments can be developed.
22nd Feb 2009
Fattysaurus rex
We usually think of dinosaurs as huge great beasts, roaring about and generally being terrifying. Now researchers at the University of Manchester have used laser imaging to reveal whether our favourite prehistoric beasts were trim and fit, or big old fattysauruses.
Writing in the journal PLoS One, Karl Bates and his team used laser imaging and 3-D reconstruction techniques to recreate the bodies of five dinosaurs of differing sizes as they might have appeared in real life. They looked at two Tyrannosaurus rexes, an Acrocanthosaurus atokensis, a Strutiomimum sedens and an Edmontosaurus annectens. Their results suggest that the smaller of the two T. rexes could have weighed anywhere between 5.5 and 7 metric tonnes, while the larger one might have weighed in at 8 tonnes.
They also think that Acrocanthosaurus atokensis, a big predator similar to T. Rex weighed around 6 tonnes, but the ostrich-like Strutiomimum was probably a weeny 04-0.6 tonnes, while Edmontosaurus weighed in at just under a tonne.
To get their reconstructions, the researchers used a laser scanning technique called LIDAR to image each dinosaur's skeleton. They then used and computer modelling methods that can create a high-resolution 3-dimensional computer image of the skeleton, which they can use to investigate the potential mass of the living dinosaur, its internal organs, and its movements.
After making these reconstructions, the team then tweaked the sizes of the body parts and organs to find the maximum and minimum masses that the animals might have been. Although we’ll never be able to know exactly how fat or thin they were, this analysis tells us the range of possible body masses that are physically possible.
And because of the lack of cakes and telly in prehistoric times, the researchers think that the dinos probably come in at the lower end of heir predicted weight ranges, as there’s no biological need for them to be fatties, as this would slow them down, making them less effective predators, or easy prey.
To demonstrate the accuracy of their models, the researchers applied their techniques to a modern-day ostrich skeleton, and found that their predicted mass measured up pretty well against the living bird.
The next steps – literally – for the researchers will be to use their models to make predictions about how the dinosaurs walked and ran, which will tell us more about their lives and evolution.
References | |||||
| - K Bates et al (2009) PLOS One 4(2): e4532. | |||||
22nd Feb 2009
Meningitis in Disguise
Professor Susan Lea, Oxford UniversityChris - Professor Susan Lea has a paper in the journal Nature this week, explaining how the bacteria do this and manage to hide themselves. Susan, how do they disguise themselves?
Susan - Hi, Chris. Well the work came to us in a problem that was brought by Chris Tang at Imperial College. He’d been working with meningitis for many years, looking at the bacteria and trying to understand them in more detail, trying to generate therapeutics. They’d noticed a couple of years ago that the bacteria somehow managed to mark themselves as human cells by coating themselves in a protein that circulates in our own blood, called factor H. This protein is a very important part of how we regulate our own immune response in that we’ve got one arm of our immune system that essentially seeks to destroy anything it comes into contact with in the blood. To protect our cells we develop a series of sugars on our cells that then bind a protein called factor H which turns off this part of the immune system.
Chris - How do the Neisseria meningitidis bacteria exploit that?
Susan - Neisseria can’t make the same sugars that we make. They don’t have the machinery to make those sorts of chemicals. Instead the Neisseria has chosen a different route and manufactures another protein. Instead it uses this protein to essentially seek out and bind the factor H to coat the bacterium in factor H: the way our own cells have done but by using a very different chemistry underlying the reaction.
Chris - Your work has been to discover the structure of that protein to work out how the bacteria grab this protective, this disguise factor H from the blood and then decorate themselves with it?
Susan - Absolutely. We’ve worked with Chris to generate the structure of the actual complex between the proteins of the bacteria and the proteins from our cells. In doing this it allows us to see how the bacteria uses the chemistry of proteins to mimic the chemistry of sugars that we have on our cells. The interactions are actually very similar. Some years ago we looked at the structure of sugars binding factor H. We found the structure of this protein binding factor H mimics the same sorts of interactions that you use in protein-based chemistry rather than sugar-based chemistry.
Chris - And how, now that you’ve got that structure, will this help us to get a vaccine? We’ve had a vaccine for the A strain of meningitis for a long time and that’s helped in places like Africa. We’ve had the vaccine for strain C which has made a dramatic difference for young people, especially people going to university. B has always been the big problem. 90% of meningitis cases in Britain are down to group B. How is this going to help us get a vaccine against this now?
Susan - Essentially the protein we’ve done the structure of is actually one of the components of the vaccines by both Novartis and Wyeth that are currently in phase through clinical trials are looking quite promising. We think, from looking at our structure, we predict that by altering a very small part of the protein we can make a protein that will no longer bind with factor H and we suspect that this will make a much better vaccine. It won’t have a large part of its surface covered up my factor H. When you immunise somebody with the current versions of the vaccine trials that are going on – in fact much of the bacterial protein will be hidden from the immune system because it will be bound to factor H. You therefore won’t get as good an immune response against it as you might otherwise get. We’ve made versions of this protein which are more than 98% - 99% identical to the natural form but they no longer can bind factor H. We think that these will be much better candidates for targets in the vaccine.
February 2009
Seeing further - DIY telescope
Dave builds a makeshift telescope from a pair of magnifying glasses - but be careful not to get dizzy - the image it produces is upside down!
What you need
| A magnifying glass |
| A handlens or another magnifying glass with a much higher magnification. |
What to Do
Hold the handlens close to your eye, and then hold the magnifying glass in front of it.
Slowly move the magnifying glass away from your face until you see an in focus image.
What may Happen
You should find that the pair of lenses produce a magnified but upside down image.
What is going on?
If you hold a piece of paper behind a magnifying glass, then the magnifying glass will focus the light from the scene into an image on the paper. This is called a camera obscura and is the basis of how your eyes and all cameras work. ( Find out more )
If you used greaseproof paper as the screen you could use another high magnification magnifying glass to magnify the image on the paper you would see an inverted magnified image of the scene.
In fact the light leaves the piece of paper in exactly the same way as it leaves the focus when you remove the paper, so it works even better if you take the paper away, and you have a telescope.
This is a Keplarian telescope, and is probably the most simple type of telescope to build, but there are a huge variety of other types with various advantages and disadvantages.
We spoke to Dr Carolin Crawford, from Cambridge University, about how this telescope compares to historical, and modern telescopes. You can listen to, or read her response here.
Written by Dave Ansell
MRI Scanning the Stars
Professor Alyssa Goodman, Harvard-Smithsonian Center for AstrophysicsChris - That’s exactly what Professor Alyssa Goodman from Harvard University is doing. She’s taking some of the systems that have been geared up to do better body scans with MRI and applying them to images of the night sky to enhance those pictures and she’s with us now. Hello Alyssa. Thank you for joining us. Tell us a bit more about this work.
Alyssa - We have a challenge in astronomy that more and more often we’re able to get a third dimension of data: something like distance, not always exactly distance. Instead of seeing just a flat sky we can see thing where we know what distance. We can see in my work, for instance, gas clouds that are busy forming new stars. We like to see what they look like the way that we could go around 3D clouds in the sky. Of course you can’t do that in astronomy. We need a way of putting the images back together into something that looks more like a 3D picture that turns out that the computer software to do that we need is similar to the software that they use in medical imaging.
Chris - Why is it such a problem, compiling images into three-dimensions like that?
Alyssa - It turns out it’s less of a problem in other fields and in astronomy people are just not used to having that kind of information. They were starting to try to build their own software and then we realised that a lot of other people have faced this ad done a good job of, for example, making animated movies. You may know that Pixar and companies like that have some of the most powerful computers around. It turns out that 3D animations, moving 3D pictures is rather computationally intensive to do high resolution. People in other fields, as I mentioned before – notably medical imaging and in film, movies and Hollywood – had figured that out quite well. We’re trying to borrow on what they already learned.
Chris - When you start doing this do your images literally come alive? Can you see things that, can you identify details that have previously been overlooked?
Alyssa - One of the things that we’re interested in, in my own work which has to do with star formation, is what the impact of jets of material and expanding shells from stars have on the clouds that the stars are forming in. Imagine terrestrial clouds and you set off a bomb in it and you want to see if the expansion wave, some kind of sphere expanding from that bomb looks like. You’d really love to be able to see a 3D image of that. When stars set off either supernova explosions of just powerful winds from stars the same kind of thing happens to these clouds that they’re in. It’s very important for us to understand what that looks like. In a lot off cases it’s difficult to see that happening. It’s important to view what happens to these clouds over millions of years as they evolve. This software has let us, among other things, see the outflows and shells that come from these stars in a 3D way that the human brain understands which was very hard to see when looking at just slices of the images before.
Chris - Can researchers begin to speculate that, in fact, our own solar system (in other words, the sun and our clutch of planets) actually get buffeted into existence by a big star nearby that was doing something similar to what you’re describing? It was putting a jet of material out which pushed a cloud of gas to make it fall into itself, which then formed us?
Alyssa - Absolutely. There’s a theory called triggered star formations and the idea is there are these gas clouds out there which are marginally what’s called self-gravitating. They’re sort of held together by their own gravity but not quite. They might blow apart, they might collapse but if you come by and push them a little bit – sort of trigger – then they’re more likely to collapse quickly and make something like our solar system. One way to do that is having a big blast wave either from one of these outflows or some sort of shell, possibly a supernova come by.
Chris - What are you looking at, at the moment? What’s the prime focus of study?
Alyssa - Right now we have something we’ve been doing over the past five or six years called the COMPLETE Survey of Star-Forming Regions. That’s a long, funny acronym you can look up online. What it does is it looks at some of the nearby star-forming regions using every technique we can use from the ground. Optical wavelength and radio wavelength. Radio is where we can make these three dimensional images. With the Spitzer Space telescope, which is the infrared part of the Hubble telescope, has also looked at these same regions. They’re essentially targeted regions where we essentially want to understand the whole process of star formation. What we’ve been able to do with this 3D imaging project that we call astronomical medicine is to be able to give people 3D views of what these very large regions of space look like, to be able to put back together in our minds a picture of what’s going on. From that picture we make hypotheses. Recently our work is about the details of the role of self gravity, how likely little bits of this gas are to collapse over time on themselves and to understand whether our theories are right. The best way to do that is to see a picture of what they mean. We’ve been able to convince people that we think we’re on the right track.
Chris - And you have some spectacular pictures on your own website. If anyone listening on the radio wants to check it out, where’s the web address so they can take a look at those pictures?
Alyssa - The best way to do it is to just type my name: Alyssa Goodman in Google and I think it’s the first link that comes up.
Alyssa's website can be found here, and there are some fantastic pictures, movies, virtual reality objects and even a 3d pdf available on the Harvard IIC Websites.
February 2009
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How long does it take for heat to reach us from the sun?How long does it take for heat to reach us from the sun? It’s about 8 minutes, the distance between the sun and the Earth because light travels at about 1 billion km/h and the sun is about 150 million km away from the Earth. Phil Kenyan |
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Chris - The answer is that heat arrives in the form of light because it’s in the form of infra-red radiation, largely, that’s reaching us from the sun. It’s reaching us in the form of radiation so that too takes 8 minutes to get here. |
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February 2009 |
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Phil Kenyon asked the Naked Scientists:
Hi Chris,
I enjoy your section in the Redi Direko show on Cape Talk and wondered if you could discuss the following?
I was thinking about what would happen if the sun suddenly 'went-out'!
Would we have 8.5 minutes of sunlight and 14 years of heat?
299792 km/s - Speed of light
152000000 km to sun
507.02 seconds for sunlight to arrive
8.45 minutes for sunlight to arrive
0.34 km/s speed of sound
447058824 seconds for sound to arrive
Therefore 14 years for sound to arrive
Speed of sound = speed of heat
Therefore it takes 14 years for heat to arrive?
Regards,
Phil Kenyon
(Somerset West)
What do you think?
- Phil Kenyon - 12th Jan 09
Why? - Chemistry4me - 12th Jan 09
Sound doesn't travel through a vacuum so 'heat' wouldn't get to us that way. The 'heat' transfer you refer to is what can happen in gases liquids and solids - molecules vibrating and bumping into each other. The speed of sound in the medium affects the speed of heat conduction but: The heat which arrives from the Sun is in the form of Infra red radiation (another wavelentgth of electomagnetic wave). (Same speed as light). - lyner - 12th Jan 09
As the sun flickers out there will be no more photons coming our way. When those photons stop our 'light' goes out. That will create a rapid cooling. The only heat will be from our Earth's core. That will not be enough to warm the surface and the air. All the water falls out from the atmosphere. And I suppose the air will break down into a supercooled gas? very few organisms will survive this. Perhaps inside the earth? How fast Earth will cool depends on how much warmth it has before. And how fast that heat will dissipate. I would guess the planet would be dead in a couple of days. As for heat in air? You lost me there. - yor_on - 12th Jan 09
Sorry for being nitpicking, heat is in the form of all the electromagnetic radiation.
- lightarrow - 12th Jan 09
Feel free to pick all you like, my friend. I was being deliberately sloppy in an attempt to seem more approachable. I shall avoid it in future. :-) But I could nitpick back and say that em radiation is not heat (i.e. internal energy) at all but electric and magnetic energy (or even the dreaded photons). Heat is a term which is used very sloppily. - lyner - 12th Jan 09
Hmmm...yes, but, wouldn't you define heat as those energy exchanged between two bodies by virtue of a temperature difference of them? Just thinking.
- lightarrow - 12th Jan 09
How about this definition of what would happen to our Earth if it cooled down by an absence of Sun :) "The atmosphere on earth is about 10 km thick. Ten kilometer is how far atoms at room temperature can move against the gravitational force. If the temperature of the air were ten times smaller (which is about 30 K or -240 degrees Celsius), the atmosphere would be only 1 km thick. At 30 microkelvin, the atmosphere would shrink to a mere millimeter, and at 30 nanokelvin, the height of the atmosphere would be 1 micrometer, hundred times less than the thickness of the human hair. (Of course, air is not an ideal gas and would have liquified by then). " "Freshly liquefied air consists of 78.1% nitrogen, 21.0% oxygen, 0.9% argon, and very small amounts of rare gases and hydrogen in solution. Its boiling point is approximately −195°C. Because of fractional evaporation, its oxygen concentration and its boiling point increase with time. ..As the temperature of liquid air rises, the nitrogen evaporates first at −195.8°C, the argon next at −185.7°C, and the oxygen last at −183°C." Seems chilly. the solarsystem seems to have a temperature around 40-50 K (-233 - -223 C.) But I still don't know how long time it would take? Black body radiation? - yor_on - 13th Jan 09
you suck my coch or die
See the whole discussion | Make a comment- mudder fukker - 22nd Feb 10
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Celebrating the International Year of Astronomy
Steve Owens, Professor Lord Martin Rees, Dr Darren Baskill.Meera - This week, I’m at the Royal Observatory in Greenwich for the UK launch for the International year of Astronomy. There’s loads going on here tonight, including telescope viewings, models of early telescopes and planetarium shows. Amid all these events I’ve tracked down Steve Owens who’s the UK coordinator for the International Year of Astronomy. Steve, what are your aims for celebrating astronomy this year?
Steve - We’re looking to use the International Year of Astronomy as an opportunity to inspire people, to make them enthusiastic and astronomy, to find out things they haven’t found out before, to go outside at night and look up at the sky. That will hopefully have the effect of increasing the number of scientists we have in the UK and help the UK develop its science.
Meera - To get people excited about astronomy this year what have you got planned?
Steve - We’ve got things happening around the country. The best place to find out what’s happening in your area is our website: www.astronomy2009.co.uk. We have 2000 events already on our calendar and we’re getting hundreds more in every week. Local astronomy societies are planning events. University Astronomy departments are running open days, people who own observatories are opening them to the public. We have online activities, for example, we have a cosmic diary where astronomers are blogging their lives and activities. There are literally thousands of activities happening.
Meera - Are there particularly big or main events that are happening at key moments during they year?
Steve - We’re focussing a lot of our activities on what we’re calling spring moon watch and autumn moon watch. If you like, they’re the National Astronomy Weeks for this year. They’re running from the 28th March to the 5th April and the 24th October to 1st November. Those are opportunities to get everyone in the country out looking at the sky. There are other big dates, big anniversaries: for example, Thomas Harriet, who was the British Galileo – he beat Galileo to it in 1609 on July 26th. He observed the moon through a telescope for the first time. No one had ever done it before. Galileo did it a few months later but Galileo was a good self-publicist. He told people about it and became famous. Thomas Harriet didn’t tell anybody and therefore is not consequently very famous. We are celebrating his life and his achievements in the very place he observed, exactly 400 years to the day after he made his observation.
Meera - I’m now here with the Astronomer Royal and President of the Royal Society, Professor Lord Martin Rees. In the 400 years since Galileo made his observations, what do you think the main discoveries in the field of astronomy have been?
Martin - Galileo was the first person to use an instrument to enhance what you could see which the unaided eye. Astronomy has always been at the forefront of technology, ever since that time. Here at the Royal Observatory precision instruments were made to determine longitude and measure time. Now, of course our knowledge of the universe is enhanced by very sensitive ways of detecting wave light and enhanced telescopes on the ground and in space. It’s always been technology that’s driven science and, of course, the science feeds back into astronomy. Through those developments we have come to realise the scale of the universe and the very wide range of objects in it: galaxies, stars and planets.
Meera - What would you say the main questions that remain unanswered today are?
Martin - Well we’re still just beginning. I would say that we would like to understand how our universe evolved from simple beginnings about 14 billion years ago into the complex hotchpotch we see around us of galaxies, stars, atoms and, on at least one planet, a complex biosphere where we’ve evolved. Another thing we’d like to do is to understand the planets around other stars which have been discovered just in the last ten years. I think in the coming decades we will realise that each star we see in the sky is the centre of a retinue of planets which are just as interesting as the planets we’re used to in our solar system. We may know whether there’s life on some of them.
Meera - What area of astronomy are you particularly focussing on at the moment?
Martin - Well I’m interested in understand how the first stars and galaxies formed and how long after the Big Bang that happened. I’m also interested in rather more speculative questions about how big the universe is. That might sound a strange question but the part of the universe we see with our telescopes, which extends about 10 billion light years away may be just a tiny fragment of physical reality. We’d like to know how much more there is beyond what we can directly observe.
Meera - As I mentioned, there’s a whole host of activities going on tonight, one of which is a planetarium show, showing people what to look out for in the night sky this year. I’m now in the planetarium with Darren Baskill, one of the astronomers here at the Royal Observatory. Darren, what are the things people should be looking out for this year in the night sky?
Darren - The moon is always a beautiful sight and it’s a wonderful object to look at through, even binoculars. Then there’s the planets Jupiter and Saturn. They will both be visible throughout the year. The rings of Saturn you can see through even a small telescope and if you’ve got really good eyesight you can see the rings of Saturn through binoculars. Jupiter also has over 60 moons but four of those moons are so big and so bright we can easily see those moons in binoculars.
Meera - The sky’s a pretty big thing so which direction should people be looking in to see these planets?
Darren - The planets are very bright in the night sky. In the summer if you look towards the south, at about 9/10 o’clock in the evening Jupiter will be the brightest object in that direction.
Meera - Are there any other highlight as well as planets that people can look out for this year?
Darren - Yes well early-on at the beginning of the International Year of Astronomy in the winter months will be dominated by the constellation of Orion. Look south in the evening sky throughout the winter. There’s a bright red star called Betelgeuse and there’s a bluer star called Rigel at the bottom of Orion. If you look for two stars, quite close to each other, but separated by a hand span at arm’s length – one bright red star and a bright blue star – you’ve probably found the constellation of Orion.
February 2009
Dwarf Galaxies from Primordial Clouds
Dr David Thilker, The Johns Hopkins UniversityChris - Scientists have discovered a new type of Galaxy. They’ve been using a NASA space telescope called GALEX – the galaxy evolution explorer which can see ultraviolet light. A team of US scientists have been studying a patch of the sky called the Leo ring. This is thought to be a leftover remnant from the Big Bang. It’s basically a huge cloud of hydrogen and helium. What scientists saw in there were signs of newborn stars in little galaxy sized clumps inside that ring. To tell us why that’s important and why they didn’t see any dark matter to go with it here’s David Thilker.
David - What we’ve done is discovered a new, unexpected type of galaxy, a dwarf galaxy forming in the local universe. These galaxies are odd because they have apparently condensed from pristine gas without the help of dark matter anyway.
Chris - Can you just explain that a little bit? When you say this is made from pristine gas, what do you mean by that?
David - In the universe today there are very few remnants of the material from which all other galaxies formed. The best known candidate for one of these pristine primordial clouds is the Leo ring. It’s a structure 600,000 light years wide, consisting only of hydrogen and helium in a nearby galaxy group about 30,000 light years from us. Evidence is that this object has been around from the time that galaxy group formed and has been doing nothing ever since.
Chris - How have you tried to understand or to explore this distant mass of gas? What do you think it’s been doing?
David - The GALEX satellite that I’ve been using, the Galaxy Evolution Explorer is a telescope in Earth orbit launched by NASA and the UK in 2003. We’ve been surveying the entire sky in ultraviolet wavelengths that are sensitive to the process of star formation. What happened was I was looking at a galaxy that was nearby this Leo ring. I knew this primordial cloud was in the field of view of this other galaxy. I thought, why not go ahead and see if we see any evidence for star formation. At that point it was possible to detect something.
Chris - Why do you need UV in order to do that? Why can’t you just use normal light telescopes?
David - The UV is best for detecting star formation because the most massive stars are several times more massive than the sun, emit most of their light in the blue part of the spectrum. They stand out like a light post to the ultraviolet telescopes. Those stars are the most massive ones and live a very short lifetime. If you see them you know they’ve essentially just formed. It’s a combination of the colour and the lifetime of the star that allows us to see star formation with the ultraviolet.
Chris - When you use the UV cameras like this to look at this distant entity what do you see and what is that telling you?
David - When you look at the Leo ring in the UV wavelengths we have detected ultraviolet emission coming from clumps within the gaseous ring. Those clumps are much smaller than the size of the Milky Way galaxy, for instance. They qualify as dwarf galaxies. The interesting thing about this detection is that these radio observations, the same ones we used to discover the gas of the Leo ring, also indicated there was no dark matter within those clumps of the ring. You have this combination of ongoing star formation and no dark matter within a cloud of pristine gas. It’s really something quite unique that hasn’t been seen before.
Chris - Why do you think it’s not there and yet, if you look at all the other galaxies that we have around us, such as our own, you do see lots of dark matter in the centre? Why is this different?
David - It’s just that the process of structure formation in the universe, essentially the dark matter acts as a seed. You have this process of gas collapsing onto dark matter. This happens to be one filament that doesn’t appear to have completed that process. It’s still floating away in this galaxy group but it hasn’t actually accreted or fallen on to the more massive galaxies in the centre. It’s somewhat of an oddball in the fact that it still exists at this point.
Chris - What is this telling us about the universe from which we all sprang? Our galaxy and the others that we know are out there? What insights does this give to the early phases of the universe?
David - I think it tells us that the universe can still surprise us first of all and second of all that there may be more ways to form galaxies than we had previously recognised. In particular, the process of dark matter had dominated the galaxy formation, it may not be the only one.
February 2009
Science of Stargazing & Telescope Technology
Carolin Crawford, Cambridge UniversityWe invited Carolin Crawford to see what she thought of the telescope Dave built for this week's Kitchen Science, then asked her how it compares to a real telescope...
Ben - Carolin, Dave has a very simple telescope but is this really what the first telescopes were like?
Carolin - It’s actually a very good example of what the first telescopes were like and it’s got the principle components you need. The first magnifying glass that Dave’s got is the larger one. That’s the one that collects all the light from things that are very faint. It makes them brighter. The second magnifying glass is what you need just to make that image bigger. It’s supposed to be the principle component of any telescope we still use today.
Ben - Does that include this enormous thing behind us? I’m assuming it is much more powerful?
Carolin - It is. The one we’ve got behind us is still quite old. It dates from 1838 but it’s the same principle as Dave is demonstrating with his telescope. Instead of being a handheld magnifying lens it’s actually one which is 12” in diameter. You can imagine that can collect an awful lot of photons from a distant source. The catch is to collect that and bring it down to a focus you need a tube that’s just short of 20ft long. At the other end we have what we call the eyepiece. Really, that’s just a glorified magnifier like Dave’s second magnifying glass. We can change that around and get different magnifying strengths depending on whether we’re looking for something that’s small and star-like or large and fuzzy. You want different magnifications for different objects but the basic principle is very much the same.
Ben - How have telescopes moved on since these basic principles?
Carolin - Well, the kind of telescope we’re demonstrating here is just one kind of telescope called a refractor. Most of the large telescopes today are reflecting telescopes. This idea was brought about by our own Isaac Newton, here in Cambridge. The idea here is that curved mirrors can have a lot of the same properties as curved lenses in the way that they will bend and bring light to a focus. The advantage of using mirrors is first, of all, the light gets folded up and gets bounced around between mirrors in the telescope. The telescope itself is a lot less cumbersome and a lot easier to move around. It doesn’t have to be so long as a refracting telescope. There’s a problem with these telescopes that use lenses in that you can only make the lens so big before it starts to sag in the middle. If you think of it you’re holding it in place around the edges. If you get something that’s appreciably more than 40” across the centre begins to deform under gravity and that distorts the images. If you want to go bigger you’re really looking at using mirrors. They’re much more reliable and they’re much easier to make and transport. The very largest telescopes we use today all use mirrors. Those mirrors are all of the order of 8 – 10.5m across.
Ben - That sounds enormous. How do you make sure a mirror that size is exactly the right shape? I’d have thought it was so easy to go wrong and then ruin your entire telescope.
Carolin - The prime example of that is the Hubble telescope where they did get the curvature of the mirror wrong and there was a very big problem when it was first launched into space because all the images were out of focus. Usually we do test this quite thoroughly. There are also new and exciting experimental innovations which involve making mirrors out of segmented mirrors to mock up an even larger surface. There are many advances in how you use mirrors in a reflecting surface. It doesn’t just have to be one solid mirror.
Ben - A lot of what is going on in space science now is not looking at visible light. Mirrors, lenses are very good at collecting visible light. How do we look at the things that we otherwise can’t see? X-rays and microwave radiation?
Carolin - We’re only talking about the visible side of astronomy and astronomy stretches right from gamma rays, x-rays, ultraviolet down to radio and infrared. Radio signals are collected on massive parabolic dishes. People may have
seen that in terms of Jodrell bank and here in Cambridge, the radio dishes just outside of Cambridge on Barton Rd. There are special challenges when you want to take pictures in the UV because atmosphere blocks out the light. That has to be done from orbit. You get some really exciting challenges from x-ray astronomy because x-ray photons have so much energy in them they would just slam into the surface of a conventional optical mirror. You can only bring them into focus if you put the mirror edge-on to the x-ray photons. It sort of ricochets off the mirrors and is brought into focus that way. If you looked at an x-ray telescope it would look nothing like the one Dave’s got here. It would be a set of nested cylinders collecting photons and bringing them to a focus at the end of the cylinder. There’s a huge variety of ways that astronomers use telescopes to do their astronomy.
February 2009
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Why do leaf shapes vary so much?If you look at trees, often closely-related trees, growing in exactly the same ground in exactly the same climate they have different-shaped leaves. Why? People will say, “it’s the airflow over it in different particular circumstances or the way that the water drips off it,” that’s the reason. But the trees are growing in exactly the same places alongside one-another. Why do they have different-shaped leaves? Sir David Attenborough |
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We put this to Ed Tanner, Senior Lecturer in Plant Sciences at Cambridge University I think the answer to the question about why closely related trees growing in exactly the same ground and the same climate have different-shaped leaves is actually that they don’t. |
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February 2009 |
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I would guess this could be the result of a combination of different trees requirements and the insect and other animal residents and visitors to which each tree plays host. A tree requiring a great deal of water and/or water borne nutrients would require a bigger and broader leaf than one which has less such requirements. For example a fruit bearing tree might need more nutrients than a non-fruit bearing tree. Larger and broader leaves would allow a greater rate of evaporation, thus drawing more water and nutrients from the ground. The larger leaf area would also mean a greater rate of photosynthesis. A tree may also benefit from the creatures it plays host to. Supplying the right size and/or nutritional value leaf could be the price the tree pays in return for the protection of the insects which live in it's canopy, or the animals which will spread it's seeds when the time comes. - Don_1 - 18th Feb 09
The climate would be the same for neighbouring trees, but not constant over the lifetime of a tree. Over the lifetime of a tree (decades) climate (e.g. rainfall) would not be constant. During this lifecycle the changing conditions would sometimes favour one type of tree, sometimes the other. So different tree types existing side-by-side is a bit like nocturnal and diurnal animals existing in the same territory, only the cyclic period for the trees is decades long, not daily. http://www.math.utah.edu/~adler/oldcourses/math5110/reprints/armstrong.pdf - RD - 18th Feb 09
You will also find that much of this is down to genetic variability. The internal coding of a particular species that would be inherited by its offspring (its genotype) holds all the instructions for the next generation. During the interpretation of this information various anomalies may occur and provide the variability that drives the evolution of the species. This is the phenotype, or the actual physical manifestation of the genotype. There does not actually need to be any environmental input to drive these "within group/species" differences in leaf shape and size at all - it can all be explained by this genotype ==> phenotype process.
- dentstudent - 18th Feb 09
If a genetic variant was better adapted than its predecessor and environmental conditions were constant, then the superior variant would outcompete and eventually eliminate its predecessor. There have to be cyclic conditions for coexistence. http://www.biology.duke.edu/wilson/research/papers/papers/2005WA.pdf - RD - 18th Feb 09
RD - My point is only that this interpretation of genotype into phenotype can also explain a degree of variability within a species. Even if there was only one individual say, that produced many offspring (as is the case in many pioneer species of tree, for example birch), then there would be variation within that group due to phenotype, and hence also a degree of within population leaf size variability, for example. The environmental changes do not alter the phenotype interpretation, only (as you say) those individuals who may benefit because they are better adapted because of their phenotype.
See the whole discussion | Make a comment- dentstudent - 19th Feb 09
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Because they’re closely related they are very similar. For example, all oaks have broadly similar-shaped leaves because they share most of their genetic information. Perhaps a more interesting question is why distantly related trees growing in the same ground and in the same climate have different shaped leaves. The answer is it doesn’t matter very much. As long as leaves are reasonably good at doing their job, which is fixing carbon dioxide in the atmosphere it doesn’t matter whether they are wavy at the edges or not wavy at the edges. They have to absorb the light and once they’ve absorbed the light they would fix CO2. As long as they put their competitors in the shade any reasonably functioning leaf will do the job. It matters where your leaves are in relation to other trees. If you’re an ash tree you’ve got to be above an ash tree or if you’re a beech tree you’ve got to be above an ash tree. It doesn’t much matter what your leaves are like.
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How do we know that another planet collided with the Earth?How do we know that another planet collided with the Earth? I saw a TV programme that said during the Earth’s evolution another planet called Thea smashed into it. How do we know this when it doesn’t exist anymore? Peter Robinson |
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Chris - Well, we have to go by what the models are telling us and what samples we’ve got. We’ve got a very large moon around the earth. In fact, it’s unfeasibly large for a planet of our size. Why have we got such a big moon where it is? What the prediction is, and based on what we know about the composition of the moon from samples that the Apollo astronauts have brought back is that the moon is made of exactly the same stuff, give or take, as the surface of the Earth – the Earth’s crust. The big question is how did something made pretty much of the same material as the Earth end up orbiting the Earth unless something bashed it an put it up there? The best suggestion that scientists can come up with, based on all the evidence we have, is that during the early phases of the formation of the solar system (something like 4.5 billion years ago) there were two planets. One a future Earth, one another planet which they’ve notionally called Thea. These were very similar in terms of their orbital pattern. One ran into another – it was like cosmic billiards that went on. As a consequence of their massive great collision the cores of both planets effectively fused. In the course of this collision a lot of the surface material from the Earth got ejected into space and it formed a sort of shroud around the Earth which slowly coalesced in the same way that rings around Saturn have coalesced to what would have originally been an envelope. They then coalesced and aggregated to form the moon. It’s on the basis of there’s no other better explanation than that one to explain why we have this phenomenon of this big moon and what the moon’s made of. |
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February 2009 |
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peter Robinson asked the Naked Scientists:
A TV programme stated that during Earth's evolution another planet, Theia?, smashed into it. How do they know this, how do they know when and how do you name a (now) non-existent thing?
What do you think?
- Pe-Pe - 19th Dec 08
We don't know it because there was no one there to witness and record it. However, the consequences of it are apparent today and these form a record of evidence for which the planetoid collision scenario is by far the best fit solution.
- LeeE - 19th Dec 08
LeeE: Is correct;too see this evidence you simply have to look up.The answer to this question;began with another question.Where did the moon come from? Not only do we have our own moon but we only see one side of it the reason for this is in its early stages of formation the moon was molten like lava in fact it was lava. The liquid moon began to cool at the same time as it orbited our planet the gravitational pull of the moon on the earth so close to our planet in its original orbit slowed the rotation of the earth. The way this works is through the tidal forces that still pull at the earth today;Kind of slowing the planet like dragging A boat paddle throw the water to slow A canoe. At the same time the earth is doing the same thing to the moon;as the moon cooled it became more solid and eventually locked its rotation to its orbit around our planet. Soil samples from the moon have been studied and are known to be made up of mostly the same material as found on our planet.So Either some thing come along and sliced A moon size chunk off A much bigger earth;(man that's A big knife!)or A smaller earth collided with A smaller planet that was moving in just the right trajectory to hit the planet not dead on;that would have resulted in A situation where the material would have globbed together into A single planet;but at an angle that could leave enough molten material in orbit after gravity and friction had it out;too form our moon... Hope this helps TECHFACTOR:OUT
- TECHFACTOR - 19th Dec 08
You can find all the evidence of Thea in a book called; the cataclysmic impact/planet earth's most violent intersect. It clearly provides an abundance of evidence, concentrating on Earth's biggest and most profound impact crater.
Vredefort, Barringer, and Chicxulub craters combined, would not equal a quarter of this impact's enormity.
- DR - 23rd Dec 09
OK, seems logical- but then where did the rest of Thea go to??
- Wells - 12th Jan 10
The Earth is believed to have absorbed the other planet which had been in the same orbit as Earth. It slowly caught up to the Earth. It was a Mars sized planet. They collided at small angle instead of a direct collision. This allowed the Earth to absorb the other planet. Most of it is believed to have gone into the core of the Earth making it just right for us today. The entire planet was molten for quite awhile. The collision is also believed to have blew off excess water into space so we ended up with the perfect amount for us today. The collision also threw out a lot of rocky type debris which eventually setteled into the large moon we now have that is so essential to keep Earth on a perfect axis as well as regulate tides and other things. Personally, I give The Creator credit for such a fine tuning event that made it possible for us to have intelligent life on Earth today. There is an abundance of other fine tuning facts that make the chances of this all accidentally happening numerically so small that it equals zero.
- Carl - 20th Jan 10
We do not know... The idea that the Moon was made by a glancing strike on this planet makes no sense. The reason Moon Rocks are like Earth rocks is because they are Earth Rocks. Man has not set foot on the moon. Probes, Yes.. Buzz and the boys did not pick up rocks and bring them back to Earth.
Remember back in the 90's when they claimed the found a Mars rock on Earth? Well would it not be more likely be a Rock from Theia? or Thea... the "Mars size" planet that struck this world? Nope.. they said that rock came all they way from Mars... Such Junk Science.
Our Moon is more likely to be a planet that was formed between Earth and Mars and drifted toward the bigger planet and had its orbit around the orrery captured the bigger Earth...
Any theory that requires you to believe man walked on the moon 11 times is junk.
- Bones - 25th May 10
Bones, you're an imbecile!
- CB - 14th Feb 11
Bones, what an idiot! Does he live in a cave? Muppet
See the whole discussion | Make a comment- lol - 22nd Oct 11
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How do we measure distances across the universe? |
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Chris - This is a very difficult question o answer, or at least it was. The problem is that if you’re looking at stars in the night sky; if a star is at a certain distance from you its brightness can’t really be used as a measure of how far away it is because a bigger star will be brighter and because light gets dimmer the farther it is from you a big star can be a lot farther away than a small star and yet they’ll both appear exactly the same brightness. How do you solve that one? This kept astronomers guessing for a very long time until about the turn of last century. A woman in contact with Hubble, after whom the Hubble Space Telescope is named, solved the problem. Her name was Henrietta Levitt and she was looking at star charts. She noticed that some star appeared to get bigger and brighter and then dimmer and weaker. They did it with a regular period. These have now become known as the stellar yardsticks. They’re called Cepheid variables. They’re stars that swell up and shrink down. Because the period at which they do that varies with the size of the star you therefore know, if you look at how often a star like that is blinking on and off, you know how big it is. Therefore you know how bright it is. Because light follows an inverse square law you can work backwards to work out how bright that star must be and therefore how far away it is. Scientists now use these Cepheid variables when they look at a distant star structure they can use the period of any Cepheid variables that are there to work out how far away those particular entities are. That’s a stellar yardstick and it was solved by a lady at Harvard a hundred years ago. |
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February 2009 |
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- Richard Nirui - 27th Jul 08
- lyner - 28th Jul 08
- graham.d - 28th Jul 08
- lyner - 28th Jul 08
- Hei-Tai - 25th Feb 09
- lyner - 25th Feb 09
- Bored chemist - 25th Feb 09
- Hei-Tai - 26th Feb 09
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How fast would a bullet need to leave a gun in order to get into space? |
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Chris - The forum has come to our rescue to answer this one: www.thenakedscientists.com/forum. There’s a terrific answer. RD points out that anything leaving the Earth into space needs to be travelling at escape velocity. That means 11.2km/s. To put that into perspective even a high-powered assault rifle probably fires things at 1km/s. It’s running significantly too slow in order to achieve escape velocity. It also doesn’t take into account air resistance. There’s a very good answer from BoredChemist. One thing to consider here is what about if we just build a powerful rocket and fire something from Earth? He says there’s a limit to how far you can get something to go and how fast you can get it to go using a gun. The projectile is driven by hot gases producing the explosion but the gas is made of molecules and they have a range of velocities. The hotter the gas, the higher the average velocity. To a fair approximation, the average speed of the molecules is the speed of sound in that gas. A projectile is moving faster than that the gas molecules will get left behind so they can no longer push on the projectile to make it go faster. By fudging the issue and using hot light gases like helium you could make it go a bit faster. There’s no way that’s you’ll get to escape velocity. Sorry about that! |
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February 2009 |
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David Compton asked the Naked Scientists:
In an earlier Podcast Dr. Dave mentioned that 11.2 kilometres / second was the value of escape velocity.
I was wondering how that applies in the real world? The discussion was about firing a bullet into space. If the speed of the bullet was 11.2 kilometres / second when it left the barrel of the gun, would that be fast enough to reach space?
That bullet will immediately begin to slow down due to air resistance and gravity. Would that 11.2 kilometres / second have to be increased to account for these forces?
I figure that a small .50 calibre bullet weighs 647gr (41.9g), which typically has a velocity of 928 meters/second. So my question is this: How fast would a 41.9g projectile have to going when it leaves the barrel to make it into space?
Thanks!
What do you think?
- David Compton - 25th Oct 08
Escape velocities do not take air resistance into account. Escape velocities are independent of mass: any object, whether a bullet or a bus, would have to be travelling at 11.2Km/s in space (outside Earth's atmosphere) to escape Earth's gravitational field. The speed a bullet leaves a gun (muzzle velocity) is no where near Earth's escape velocity... http://en.wikipedia.org/wiki/Muzzle_velocity - RD - 25th Oct 08
Take a look here http://en.wikipedia.org/wiki/Project_HARP - syhprum - 25th Oct 08
This was the big gun thing that some people though Saddam Hussein was trying to build at one time. The problems are enormous. The muzzle velocity has to be very high indeed and the payload has to withstand both the huge acceleration in the barrel (even though this has to be made very long to minimise this) and the huge rise in temperature due to air friction. In the reverse situation when space craft return from orbit the thermal problems, even in the thin upper atmosphere, are extreme. I suspect this would be an impossibly difficult problem at ground level, although it may be possible to get some sort of object (maybe ceramic) that could withstand the heat and acceleration. The question would be "why?". - graham.d - 26th Oct 08
There's a limit to how fast you can get soemthing using a gun. The projectile is driven by the hot gasses produced by the explosion but the gas is made of molecules and they have a range of velocities. The hotter the gas the higher the average velocity. To a fair aproximation the average speed of the molecules is the speed of sound in the gas. Once the projectile is moving faster than that, the gas molecules get left behind they can no longer push on the projectile and make it go faster. By fudging the issue and using hot light gases you can get a bit faster but there's no way you will get to escape velocity this way. - Bored chemist - 26th Oct 08
I think you can get to about 3x the velocity of sound, BC, but not much more with conventional explosive type propulsion. There is no such limit with the "rail gun" electromagnetic propulsion though. It is not exactly a "muzzle" you would have then, but I guess the idea is the same in that all the propelling force equipment stays on the ground.
- graham.d - 26th Oct 08
Ummm there's a big difference between 'reaching space' and escape velocity. For a spacecraft to reach space (the Von Karman line at 100km) needs a delta-v of about 3km/s, including air drag. Bullets are draggier though and will need somewhat more delta-v than that (depending on their length, longer is better). 11.2 km/s (PLUS air drag) is needed to escape entirely from the Earth, but that's much too fast; you don't need to go that fast to just to reach space. And the idea that a bullet can't go faster than the molecular motion (speed of sound in the gas to be precise) isn't quite right either- Project Harp involved injecting the gas in sideways with an angled boat tail on the projectile. This squeezes the bullet like squeezing a pip between your fingers and it can go significantly faster than the molecular motion/speed of sound. Note that Project Harp actually fired at 3.6km/s (about Mach 10) and actually reached space (180km in this case). There's also something called a 'multistage light gas gun'. Basically this is a way to make gas go at supersonic speeds, and this supersonic gas can be used to push on a projectile. They've achieved over 7km/s (about Mach 25). - wolfekeeper - 25th Feb 09
Very interesting wolfekeeper.
See the whole discussion | Make a comment- yor_on - 28th Feb 09
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