Tuesday, March 8, 2011

To Wish Upon a Shooting Star...

First off, apologies for not posting anything for a while. I’d make excuses, something about a PhD, but no-one would listen anyways.

Meteorites, aren’t they cool! I reckon, maybe it’s because I’ve decided to dedicate at least three years of my life to studying the things, but they are cool anyways. So, what are they?

Have you ever stared up at the night sky for a while on a clear night when the moon isn’t out? If you have, then chances are you’ve seen a shooting star, a little flash of light which briefly cuts across your view of the stars. Well, this little flash of light is actually a small piece of rock which is flying into our atmosphere. The Earth collects about 40000 tons of the stuff every year, so every night you should be able to see a couple of meteors if you hang out for an hour or two. Most of the stuff is really small, from about a few thousandths of a millimetre to maybe the size of your fist or a beach ball.
A meteor shower, the Leonids in 2001

The light itself is basically a trace of the rocks journey through our atmosphere. When they come towards Earth, these little rocks are travelling really fast, somewhere in the order of 10 to 70 km per second. By comparison, a bullet from an average gun travels at about 300 to 900 metres a second. Because they are going so quickly, the atmosphere of Earth acts like sandpaper on the rocks, heating them up and stripping material off them. So, the light we see as a shooting star is basically a rock which is getting cooked at a really high temperature.
A meteorite fireball. Pretty, huh? This one could have reached the ground

Most of these rocks don’t make it to Earth; they completely burn up in the atmosphere. Only something which is a bit bigger has a chance of reaching the surface. Things about the size of a small car will often reach the surface as a rock about the size of your fist. But, this is all dependant on when the meteorite falls. Because of the way the Earth is rotating, those meteorites which fall during the evening are travelling at much lower speeds than those which fall in the morning. Some, those which reach the ground with about the size of a truck, can leave a crater. The meteorite which created Meteor Crater in Arizona, some 1200m in diameter, was probably only about 50m in size. By comparison, the asteroid which caused the Chicxulub crater, about 200km across and the event which wiped out the dinosaurs, was probably only about 8km in diameter.
So, what are they?
Meteor Crater in Arizona

Well, basically they are pieces of asteroids or planets which have drifted into an Earth-crossing orbit. Some of them, the chondrites, represent materials which never formed into proper planets. They contain things called chondrules, small bits of molten rock which crystallised under zero-gravity. They also contain free metal, graphite and sometimes diamonds, all of which are incredibly rare in rocks on Earth. These chondrites can tell us about a lot about how planets, moons and asteroids were able to form during the first million years of the solar system. Others, are completely made of iron and nickel metal, and represent the cores of protoplanets which have been completely destroyed.
A chondrule, a melt drop which crystallised under zero-gravity

An iron meteorite, with metal crystals showing. This came from the core of an asteroid!

Perhaps the most interesting of the lot are those ones called the SNC Meteorites. This stands for Shergottite-Nakhlite-Cassignites and these are thought to represent bits of Mars which have been thrown free of the planet careening towards Earth. So, Mars really has attacked Earth, but has only really thrown rocks. But these bits of another planet give us some really interesting insights into what Mars is like. The fact that they are quite a bit like some rocks found on Earth is intriguing for understanding how planets form and evolve. We also have meteorites from the Moon, the aptly names Lunar Meteorites, and since we’ve sent people there, we also have rocks collected on the Moon. These rocks show some key differences to rocks on Earth, but are generally pretty similar to some volcanic rocks.

To get them from their asteroids or planets to Earth, you have to first break off a meteorite. The way to do this is to throw something really big at it and hope some smaller pieces fly off in the right direction. All meteorites are basically the remnants of collisions between asteroids, or between asteroids and planets. This is the only process which can throw rocks into an orbit which will cross the Earth’s, and allow people like me to walk around a desert and find a meteorite to study. They represent one of the most violent processes in the solar system, one which we haven’t seen in action until recently.
A collision between asteroids. This sort of thing makes meteorites.
Image from the Hubble Space Telescope, courtesy NASA

Meteorites are great treasure chests for scientific knowledge. If we can understand how these rocks came into being we will understand how comets, asteroids, moons and planets formed, but in our own solar system, and in others. Today, we know of over 500 planets orbiting other stars, and this number is set to skyrocket due to the Kepler Space Telescope, which in its two years in space has found 15 known planets and over 1200 possible planets. Understanding how these planets may have formed can help us understand the possible potential for life in these systems. We may not be able to go there and sample meteorites from these far off places, but we can get an understanding from back home.
Yes, meteorites can tell us about how this could actually be likely. More on that in the future...

So, now when you see a bright streak of light cross the sky on a clear night, you’ll know that might just have been a piece of another planet.

Friday, January 28, 2011

Are you sure that’s what you’re taking?

This post is going to play with your conceptions of what you’re given. I shall have a look at the great medical phenomenon called the Placebo Effect and how it can make people think that ridiculous “treatments” can work, so let’s get started.

Placebos basically trick your body into fixing itself without giving it any medication. I’ve personally had these work for me, I was given a hay fever pill which looked like an antihistamine. It worked fine until I found out that it was actually a homeopathic remedy, and it promptly stopped working. This affect is so powerful that drug companies tend to have to control for these effects when they test new drugs. Often, placebos will only be effective for mild conditions, such as hay fever, nausea and for headaches, but it can be effective for much harsher conditions.

So, how can your mind fix your body without taking any medication?

Well, the placebo effect and its evil twin, the nocebo effect, rely on a patient’s expectations for how a treatment will affect them. If a patient is expecting a treatment to make them better, then the placebo effect can cause that improvement, but it can also work the other way. If you take a pill for, say, a headache, it is better if it is a big red capsule rather than a blue chewable pill. Likewise, you’ll get a better placebo effect in patients if you give them a needle, or some sham surgery. It’s strange, but the more invasive a treatment is, the more likely you are to get better from what the treatment is treating. Also, the amount of consultation and follow up a patient has can affect their improvement as well.

So, what’s going on? To be short, we don’t really know. There isn’t anything mystical or anything, but when a person expects to get a drug which will help with pain relief, say, they will produce more natural endorphins which will help with the pain. There is something going on in the brain to tell the hormone glands to produce these things. But, there are also several different placebo effects affecting different parts of the immune system. This is basically due to the vast difference in the molecules which are produced by the body.

Ok, so we know a little about what the placebo effect is, how can it affect proper medical treatments?

Well, drug companies have to factor this into their studies to show their drugs are actually effective. This effect is well recognised in the medical literature, so there is plenty of information about how it might affect certain conditions. What isn’t so well controlled is a fair bit of alternative medicine.

One classic mistaken “treatment” is homeopathy. Homeopathy operates under the premise that what causes you symptoms will cure them too. So, if you’re suffering from anaphylactic shock from eating peanuts, you better eat more peanuts! But the crazy doesn’t stop there, they also reckon that if you dilute something, it becomes… stronger! That’s right, if there is less of the thing that’s supposed to make you better in the thing your taking, it will be better at making you better. Duh!

This becomes fairly stupid when you see how dilute some of these treatments are. So, the average concentration of homeopathic treatments is about 30C, or there is one part of the ingredient in 100 x 100 repeated 30 times, so REALLY dilute. The problem with this is they put a drop on a little pill for you to take. That little drop won’t have ANY of the crushed up peanut in it, so at least it won’t make your anaphylactic shock any worse. But, really, wouldn’t there have to be something in the water to actually get you better? You’d think so, huh?

These pills rely on the placebo effect to work. Also, homeopaths tend to be really good at consultation, and generally have really good people skills, so this amplifies the placebo effect. They also don’t test their products to the same levels which drug companies and independent trials go to. They tend to rely on what people say about feeling better or the like, and tend not to rely on independent measures of improvement.

It also gets really bad. Some homeopaths are touting things like cures for cancer and homeopathic vaccines. Now, if you’re taking a little pill that might stop your head hurting, that’s fine, but when you start telling people you can treat serious medical conditions which could kill people if not treated properly, then you’re being dangerously dishonest. I really wish these people had to test their products for their claims, but for some reason we think there is a benefit in these non-medicine medical treatments. Really, there is just medicine and not medicine. Those things which are proved to work are called medicine, whilst those which aren’t proved to work are not called medicine. If we then test something which is not medicine and find out it has an effect, guess what… it becomes medicine! This is the problem with a lot of alternative “medicine”, especially because people take what the homeopaths, naturopaths, chiropractors and other quacks say, and it can be dangerous.

Anyways, here’s a little movie about homeopathy which explains it well: http://www.youtube.com/watch?v=BWE1tH93G9U All Hail the Great Randi!

To recap: Medicine – good, Placebo effect – interesting, Homeopathy – really bad, Questions – great!

PS. sorry for no pictures this week, but you know what pills look like.

Saturday, January 15, 2011

Monsters Part 4: Big Bugs

For our final foray into the world of prehistoric monsters, we will go back to a time of forests and fires and have a look at four beasties. If you don’t like bugs, I suggest you skip this post.

Around 360-300 million years ago the world was a different place entirely. A lot of the planet’s surface was covered in dense forest and the geologic period is named after the large amount of coal present in the rock of this age. The atmosphere was also considerably different. Whilst we have an atmosphere which is about 20% oxygen, this time’s atmosphere was 35% oxygen. This had a specific effect on some of the creatures which live during this time.

One of the limits on the size of bugs in our time is the way they breathe. They have these tiny little organs, called spiracles and tracheoles, which allow oxygen to diffuse into their body, and the ability for the oxygen to diffuse limits the size of the bug. One way to make oxygen diffuse better is to increase the concentration of oxygen in the atmosphere. So, with oxygen contents which are about 175% those of today, you can get some seriously large insects and arachnids.

The first beast we’ll have a look at is possibly the least dangerous. Arthropheura was a 2.6m long relative of the centipedes and millipedes. It has the title of the largest known and invertebrate to have walked the land. These things lived in North America and Scotland and it is not quite known what they ate. One theory gives them powerful jaws and the possibility of being carnivores, whilst another theory suggests that they were herbivores. I prefer to think of them as herbivores, because a 2.6m long millipede which can outrun me and eat me is just scary. They could move quickly, likely by elongating their body, and could dodge obstacles easily. If it was chasing you, getting across a river wouldn’t help, because it was probably able to travel under water. Scary, huh?
Now, this would be scary to find at the bottom of the garden

I bet you’ve seen some pretty big dragonflies on a hot, humid day. Well, they have nothing on this next beast. Meganeura was a dragonfly with a wingspan on 75cm, and was the largest known flying insect in the fossil record. These things would have definitely make a decent noise as they flew around, so at least you would get a bit of warning before they came at you. They were probably carnivorous, so they would have tried to eat you. They had really strong wings, and probably fed on both insects and amphibians. Here’s what they looked like.
Not your average dragonfly

Next in our journey of monstrous bugs is the Pulmonoscorpius. These were really big, metre long scorpions. They would have been daytime hunters, as they had large compound eyes. They also had really large stingers with big venom glands, which they would have used to subdue their prey. They had comparatively small pincers, but their venom would have probably begun the digestion process, much like spider venom. It probably hunted and ate tetrapods, amphibians and reptiles which would have live around this time.
Metre long scorpions are not everyones cup of tea

Lastly, we will encounter the largest arthropod known to have existed. With an average size of 2.5m, the Jaekelopterus was a true under water monster. Part of the Eurypterids, these beasts are known to have had claws which were up to 50cm in length. These things were pretty much the kingpins of predators in the Carboniferous lakes, rivers and coastal environments. Whilst most were less than 20cm in length, the big beasts had large, powerful claws and tails with spikes which may have injected venom. Some were amphibious, having walking legs along with paddles, and two pairs of eyes, one pair being compound. They likely hunted fish and the like, but are also likely to have hunted amphibious tetrapods and other shelled creatures which lived at least partially in the water. So, they were mean, and sort of like the crocodiles of the Carboniferous.
A collection of sea scorpions
Hard shells are good for fossilisation

Luckily, due to the drop in oxygen levels in our atmosphere, we don't need to worry about these things coming back. They simply couldn't breath in out atmosphere. The largest arthropods we can expect to see are like the Goliath Bird-Eating Spider of South America, or the Giant Huntsman of Laos, with a leg span on a measly 30cm.

Just as a final point, if you didn't think the Carboniferous period was dangerous enough with all the big bugs, there was also a much higher frequency of forest fires. These were basically due to the amount of oxygen in the air. One of the things wood needs to burn is oxygen, and having more of it around makes things burn easier. So, if you didn’t get eaten, it’s likely you would have been cooked. On the plus side, at least your dinner would be cooked too.

Question comments or ideas? Please tell me!

Sunday, January 9, 2011

Monsters Part 3: Cretaceous Seas

Plesiosaurs were marine reptiles from which lived from around 220 million years ago, until about 65 million year ago. If you think of the normal depictions of the Loch Ness Monster, then you know what a classic plesiosaur looks like. They were large predators which live primarily on fish in the oceans whilst dinosaurs roamed the land and growing feathers. They ranged from having really long necks and small heads, to pretty much the opposite, small necks and big heads. They got about by having four rather large flippers, and essentially looked like a snake skeleton put inside a turtle shell, although they didn’t have a shell. They include things from the early 3m long beasties to possibly the largest predator to have existed, the aptly names “Predator X” (cue dramatic music).

This is Predator X, possibly 15m long, eating another plesiosaur

Plesiosaurs seem to have been coastal dwellers, as most fossils have been found in coastal and estuarine environments. They mainly fed on ammonites, hard-shelled molluscs similar in body-shape to the modern Nautilus, and Belemnites, creatures which were similar to squids. Larger varieties probably fed on smaller plesiosaurs, and some had teeth for crushing bony plates, like those on the armoured fish or turtles.

A classic image of a long-necked plesiosaur or elasmosaur

Possibly the most interesting thing about these creatures is not how they lived or anything about them at all. Some people want to think that plesiosaurs have lived on past their extinction in the K-T extinction, when the dinosaurs died. The strange thing is they have picked a hell of a spot to live. For some reason, these “modern plesiosaurs” have chosen a rather difficult environment to live in. You might think that living in salt water and fresh water are pretty much the same, but they aren’t. In salt water, you have the problem on keeping your water in and the salt out. This is basically because salt likes to disperse itself equally in a liquid. In Freshwater, you have the opposite problem, keeping your salt in and the water out. This might not be as much of a problem for large, skinned animals as it is for jellyfish (there aren’t many freshwater jellies), but it still does pose a big problem. Also, the majority of these lakes, like the quintessential Loch Ness, are in cold environments. Reptiles, especially marine reptiles, do not fare well in cold environments. Have a think of where the crocodiles live. They are pretty much an analogue of plesiosaurs, and they don’t live outside the tropics. This is basically because they don’t produce much heat in their bodies, and large bodies require lots of heat, so living in a lake that has an average temperature of 5.5°C! That and the fact that Loch Ness has only been there for about 12,000 years points to these cryptozoologists, as they are called, being wrong. These stories exist throughout the world, and they are all pretty much wrong. My favourite is the New Zealand lake monster in Lake Coleridge on the South Island. It’s called Lakey. Damn, New Zealand, that’s clever.

The most famous photo of the Loch Ness Monster, the Surgeon's Photo
 was probably an elephant.

Next is the terrifying Mosasaur.

Big, mean lizard-shark!

If you think back to Part 1 of this Monsters series, we met the Megalania. Well, good old mosasaur is pretty much a cross between that beast and a shark! They had mouths filled with long, pointy teeth, and had strong flippers and a powerful tail. They are relatives of snakes, which may surprise you, but they had very similar jaws, which allowed them to swallow their food whole. They hunted early birds, fish and sharks as well as eating smaller mosasaurs.

These things did get pretty big. Sure, the smallest were only about 3-3.5m long, but the biggest, one Tylosaurus, got to about 17.5m. They also seemed to have two sets of fangs, all the better to grab you with. These puppies lived pretty much worldwide, and seemed to prefer shallower waters. Generally, Mosasaurs were pretty successful as predators, as they seem to have had greater numbers than other predators in the sea. They outnumbered plesiosaurs and crocodiles, and seem to have filled the niche left over by the ichthyosaurs when they went extinct during the Cretaceous period. But, even being such great predators didn’t save these guys from the asteroid which did in the dinosaurs.

Mean, but at least they're all dead.

Give me something you're interested in to write about and email me or leave a comment.

Sunday, January 2, 2011

Monsters Part 2: Giant Eagles and Mega Sharks

After our look at my favourite Australian monsters, I thought I’d have a look at my two favourite monsters from the time after the dinosaurs dies. These are namely the megalodon, a huge sharked that roamed the oceans, and the Haast’s Eagle, a massive predatory bird from New Zealand.


Firstly, let’s stay dry and have a look at this massive eagle. Haast’s Eagle would have been a truly terrifying sight to behold, especially since it only went extinct around 600 years ago. In fact, the Māori have a legend about this fearsome bird, known to them as the Pouakai, a bird-monster who ate humans. And, when you find out how big this thing was, and what it ate, it’s not hard to believe in that little myth.


Haast's Eagle about to catch dinner

This flying monster stood about 90cm tall and weighed between 9 and 15kg. Now, that may not sound like much, but this thing would fly at 80km/h! Anything travelling at those speeds demands respect. Also, they hunted moa, New Zealand’s version of the emu or ostrich. The only thing is moas were much larger than their Australian or African equivalents, reaching some 230kg themselves, some 15 times the weight of the Haast’s Eagle. The fact that this predator would take something like that down is really cool.


Haast’s Eagle had a wingspan of about 3m, on par with the largest of the Golden Eagles or Stellar’s Sea Eagles, but even the biggest of these don’t get much more than half the weight of the Haast’s Eagle. It also had rather powerful legs, able to get into flight from a single jump, quite a feat for such a large bird (think of how a pelican gets into flight, and they max out at bout 13kg). The Haast’s short, strong wings were probably a benefit when hunting through the dense scrub and woodland of New Zealand. So, not only was its size amazing, but it probably was also a very agile bird. Running into a forest wouldn’t save you from this giant.


When hunting moa, the eagle would sit on a perch and stay motionless for a while until a suitable moa came along. It would then rapidly soar down and grip the moa near the pelvis with one taloned foot, whilst the other would kill the animal with a swift strike to the head or neck. This strike would have been equivalent to that from a brick which has fallen some 8 stories, quite a punch. Obviously, this 15kg bird can’t eat a whole 230kg moa in a single sitting, so it would use the same carcass for several days, and stay nearby.


Haast's Eagle and two Moa

One of the most amazing things about this bird is how recently it went extinct. The Māori didn’t reach New Zealand until about 700 years ago, and they rapidly wiped out the moa, the Haast’s main food source. It is completely likely that the Haast’s did kill and eat people, especially since we are a lot smaller than the big moas, so the legend of the Pouakai would suggest that the Māori did have contact with this eagle. But, if humans didn’t get to New Zealand until recently, it is more than likely that we would still be able to see this great, majestic beast in all its glory. Because the Māori hunted the Moa into extinction, the Haast’s Eagle could not find food, so went extinct itself.


If you’re scared of sharks, you might want to skip this bit, or you might be kept up at night.


Put your hand up if you’ve seen Megashark vs. Giant Octopus. I can’t see your hands... probably because I’m not exactly looking at you, but hey. If you haven’t, I suggest you get a couple of like minded friends, a bottle of your chosen beverage (mine’s wine) and watch the pants off this movie. It has the absolutely most terrible depiction of my next monster, megalodon.


So, you think Great Whites can get pretty big, huh? 6m is a rather large fish, hey? Well, between 25 and 1.5 million years ago there was a shark which made the Great White look like the fish you catch off the pier. Megalodon (Greek for big tooth) topped the scales at about 105 tons and a length in excess of 20m. This fish could literally swallow you in a single gulp.


Megalodon tends to make you feel small and insignificant

This fish, like many sharks, had 5 rows of teeth, but these teeth were over 18cm long. They are shaped much like great white teeth, but are more robust. This, coupled with the great size of the shark, allowed it to bite down with a maximum force of over 18 tons! That’s like having a rather large truck drive into you, and all focused along those teeth. It probably wouldn’t hurt; there wouldn’t be time for that.


So, we have a really big shark, so what would it eat? Well, whales are pretty big, aren’t they, so it could have eaten them. And true to form, there have been many different whale fossils found with tooth marks which match those of megalodon. There have also been several teeth found near fossils, so that adds to the idea that this giant shark ate whales. But, it didn’t stop there. It was probably a pretty opportunistic hunter, taking what it came across, such as seals, dugongs and manatees and even large sea turtles. It would also have eaten other fish, and possibly ate other megalodons. They could swim at high speeds, so chasing prey wasn’t a problem, and they are thought to have been rather smart predators too.


From evidence of whale fossils, megalodon probably tried to immobilise its prey by biting its fins and tail, or crushing its vital organs. It could also have acted similar to great whites when hunting seals, and attacked by ramming smaller prey from below at great speed. It kind of adds something to those images of great whites flinging seals into the air. Imagine an airborne whale!


I love it when these guys play with their food

Try this on for size. Megalodon could inhabit pretty much any marine environment. It’s thought that they had their nurseries in shallow coastal waters, and moved out into more open water as adults. Whilst it probably wouldn’t have gone up to the Polar Regions, it would have inhabited most temperate and tropical oceans, much like the great white today. This is possibly one reason it began to go extinct. As the globe cooled over the last few million years, water temperature dropped too, forcing megalodon to more equatorial latitudes. A cooling globe would also reduce the available nurseries for this beast, limiting its ability to repopulate. It also could have lost out like the Haast’s Eagle and lost its food supply, or may have been out competed by the emerging Orca. Anyways, I’m kind of glad it’s extinct, it was a true monster.


A truly terrifying beast

Next week, I’ll take a look at Nessie’s cousins and a similar predator from the time of the dinosaurs. As always, if you have comments questions or suggestions, please email me!