Now this is a cool discovery. Turns out the old idea of making gold from other metals is not as far fetched as you might think! Well, okay, so we can’t really turn metal into gold – but we can make it look like gold! At least, one scientist at the University of Rochester has figured out a way to do just that with lasers.
Dr. Chunlei Guo, professor of optics, published the paper in the journal Applied Physics Letters in January entitled “Colorizing metals with femtosecond laser pulses.” In it, the authors describe their technique of using extremely short laser burst to alter the surface of a metal. These bursts – lasting only quadrillionths of a second - melt and vaporize the atoms on the surface, which subsequently rearrange themselves in nanostructures. These nanostructures include holes, globes and rods. These structures respond to incoming light in new ways from the original atomic structure; their reflection of light is highly dependent on their size and shape. So simply by changing the laser, Dr. Guo can change the resulting nanostructures, and thus change the reflected light to be a different color. This process is different from a coating or a finish, since it actually physically changes the properties of the metal. So it won’t wear away, peel or fade. And it cannot be felt by your finger. The altered structures are simply too small for our nerves to detect, so the metal still feels like normal. As far as we are able to detect, a golden aluminum that results from this method is indistinguishable from real gold.
So far, Dr. Guo has been able to make aluminum, platinum, titanium and silver look like pure gold. For that matter, he’s also made them look black, blue and gray. And he believes he can create any color he wishes, including multi-colored iridescence like the wings of a butterfly. It’s only a matter or trial and error to find the right setting for the lasers and the metal.
So what’s the practical use of this technique? Dr. Guo has suggested uses from the fanciful – etching a family photo on the metal door of a refrigerator – to the practical – producing cars and bicycles of different colors without having to use paint. Or, perhaps, custom-designing jewelry to match the eyes of your beloved? Apparently he’s already been contacted by jewelers about that possibility.
Friday, February 29, 2008
Tuesday, February 26, 2008
The Devil Frog
Fossils are such interesting things. They allow us to see glimpses of a world gone by, of creatures we could have only imagined. Remember the giant sea scorpion? (November 29th, 2007 – “A super sized insect.”) Or perhaps you recall the reptilian mammals of the Permian extinction. (January 4th, 2008 – “The Permian Extinction.”) There have been some really unusual creatures on our planet over the years! Well, scientists are at it again. This is another example of a fossil of something that’s still around today – it just used to be a lot bigger!
Paleontologist David Krause of Stony Brook University in New York and Susan Evans of the University College London have recently announced the discovery of the largest frog to have ever lived. Published just a few weeks ago in the Proceedings of the National Academy of Sciences, it is called Beelzebufo – meaning Devil Frog. This thing was approximately the size of a bowling ball – 16 inches tall and weighing in at 10 pounds. The largest frog currently in existence is the Goliath frog of West Africa, which can reach up to 7 pounds. However, Beelzebufo – which was found in Madagascar - does not seem to be related to African frogs at all. Instead, it is related to a group of big-mouthed horned frogs in South America called ceratophyrines – also known as Pacman frogs for the size of their mouths.
Apparently, ceratophyrines are quite aggressive, especially for frogs. They are ambush predators, and with their large mouths, will try to eat just about anything that walks by. Dr. Krause thinks that the Beelzebufo was probably much the same way. It also sported some heavy armor and teeth, prompting the speculation that this guy could have been strong enough to take down hatchling dinosaurs. This guy was not an aquatic frog hopping among lily pads. He likely lived in a semi-arid environment, and hunted by camouflaging himself and jumping out at his prey.
The fact that the devil frog seems to closely related to frogs in current-day South America has given new life to the long-lived speculation as to where Madagascar actually came from. Traditionally, scientists have believed that Madagascar broke free from Africa approximately 160 million years ago, and then India almost 90 million years ago, to its current isolated position. However, some scientists have recently suggested the presence of a land bridge connecting Madagascar, Antarctica, and South America. This theory is supported by recent discoveries showing close relations between dinosaurs found on Madagascar and South America. While it would be possible for animals to migrate over the ocean, either by swimming or by being carried on some sort of float, Dr. Krause believes it unlikely that the devil frog could have done either. Frogs are not adept at dispersal across marine barriers – they cannot live in saltwater, so would not have survived a swim of that nature. And the distance between South America and Madagascar makes the float idea “sort of impossible to believe,” he says.
While this is definitely in the lead for the largest frog to have ever lived, it is certainly not the largest amphibian ever. For example, the crocodile-like Prionosuchus reached an estimated 30 feet long when it was around during the Permian period. Once again, I am glad I live in an age where the frogs, crocodiles, and bugs are all a much more reasonable size!
Paleontologist David Krause of Stony Brook University in New York and Susan Evans of the University College London have recently announced the discovery of the largest frog to have ever lived. Published just a few weeks ago in the Proceedings of the National Academy of Sciences, it is called Beelzebufo – meaning Devil Frog. This thing was approximately the size of a bowling ball – 16 inches tall and weighing in at 10 pounds. The largest frog currently in existence is the Goliath frog of West Africa, which can reach up to 7 pounds. However, Beelzebufo – which was found in Madagascar - does not seem to be related to African frogs at all. Instead, it is related to a group of big-mouthed horned frogs in South America called ceratophyrines – also known as Pacman frogs for the size of their mouths.
Apparently, ceratophyrines are quite aggressive, especially for frogs. They are ambush predators, and with their large mouths, will try to eat just about anything that walks by. Dr. Krause thinks that the Beelzebufo was probably much the same way. It also sported some heavy armor and teeth, prompting the speculation that this guy could have been strong enough to take down hatchling dinosaurs. This guy was not an aquatic frog hopping among lily pads. He likely lived in a semi-arid environment, and hunted by camouflaging himself and jumping out at his prey.
The fact that the devil frog seems to closely related to frogs in current-day South America has given new life to the long-lived speculation as to where Madagascar actually came from. Traditionally, scientists have believed that Madagascar broke free from Africa approximately 160 million years ago, and then India almost 90 million years ago, to its current isolated position. However, some scientists have recently suggested the presence of a land bridge connecting Madagascar, Antarctica, and South America. This theory is supported by recent discoveries showing close relations between dinosaurs found on Madagascar and South America. While it would be possible for animals to migrate over the ocean, either by swimming or by being carried on some sort of float, Dr. Krause believes it unlikely that the devil frog could have done either. Frogs are not adept at dispersal across marine barriers – they cannot live in saltwater, so would not have survived a swim of that nature. And the distance between South America and Madagascar makes the float idea “sort of impossible to believe,” he says.
While this is definitely in the lead for the largest frog to have ever lived, it is certainly not the largest amphibian ever. For example, the crocodile-like Prionosuchus reached an estimated 30 feet long when it was around during the Permian period. Once again, I am glad I live in an age where the frogs, crocodiles, and bugs are all a much more reasonable size!
Friday, February 22, 2008
I wonder if they were snoring?
I came across a funny – and intriguing – article in the journal Nature yesterday - “Sperm whales found fast asleep at sea.” A team of researchers off the coast of Chile was studying calls and behaviors in sperm whales when they came across an unusual sight. A pod of whales was hanging completely motionless at the surface of the water. Their noses were poking out, but the rest of their bodies were hanging vertically. And they were completely unresponsive. From all indications, they were fully asleep. They didn’t stay that way for very long – only 10 to 15 minutes. But it was enough to make Dr. Luke Rendell and his colleagues believe that they had actually observed the first example of a whale in full sleep mode.
Scientists have previously believed that whales, like dolphins and other air-breathing ocean mammals, only slept with half of their brains at a time. This would leave the other half awake to carry out essential functions like breathing and watching for predators. (You can refresh your memory on this in my entry entitled “Zzzz…” from September 20, 2007.) However, using remote monitors, scientists had also observed that sperm whales tend to spend approximately 7% of their time drifting inactive in shallow water. Before now, no one knew what they were doing. Now scientists think they do – the whales were grabbing power naps.
No one knows whether this is the only sleep that the sperm whales engage in. They may be capable of sleeping both in this full mode as well as in the half-sleep mode previously know about. Their circumstances would dictate whether they would be able to engage in full sleep or half sleep. However, it is also possible that this is the only kind of sleep a sperm whale needs. If that were the case, then that would make the sperm whale one of the least sleep-dependent mammals known.
The current record-holder on that, by the way, is the giraffe. Giraffes only sleep about half an hour a day, which is usually broken up into about six 5-minute naps. Wow! That makes me tired just thinking about it.
You can see the video of the sleeping whales at:
http://blogs.discovery.com/news_animal/2008/01/view-harrowing.html
Scientists have previously believed that whales, like dolphins and other air-breathing ocean mammals, only slept with half of their brains at a time. This would leave the other half awake to carry out essential functions like breathing and watching for predators. (You can refresh your memory on this in my entry entitled “Zzzz…” from September 20, 2007.) However, using remote monitors, scientists had also observed that sperm whales tend to spend approximately 7% of their time drifting inactive in shallow water. Before now, no one knew what they were doing. Now scientists think they do – the whales were grabbing power naps.
No one knows whether this is the only sleep that the sperm whales engage in. They may be capable of sleeping both in this full mode as well as in the half-sleep mode previously know about. Their circumstances would dictate whether they would be able to engage in full sleep or half sleep. However, it is also possible that this is the only kind of sleep a sperm whale needs. If that were the case, then that would make the sperm whale one of the least sleep-dependent mammals known.
The current record-holder on that, by the way, is the giraffe. Giraffes only sleep about half an hour a day, which is usually broken up into about six 5-minute naps. Wow! That makes me tired just thinking about it.
You can see the video of the sleeping whales at:
http://blogs.discovery.com/news_animal/2008/01/view-harrowing.html
Wednesday, February 20, 2008
A shark and a discovery
I recently learned something new about a shark - the hammerhead shark, to be specific. Now, I’m not the world’s biggest shark fan. I appreciate how they are incredibly adept hunters, how they are perfectly adapted for their environments, and how they are in essential part of the balance of the earth’s oceans. But there is something a little creepy about them – their big bulging eyes, their row after row of jagged teeth, and the way they can be whipped up into a feeding frenzy with the right conditions. But of all the sharks that I know of, one of my hands-down favorites is the hammerhead. Quite frankly, I think hammerhead sharks are some of the coolest looking sharks around!
There are 9 different kinds of hammerhead sharks currently known – scalloped, great, smooth, whitefin, scalloped bonnethead, squarehead, scoophead, shovelhead and smalleye. The great hammerhead is the biggest, capable of reaching up to 20 feet long. Most of them are much smaller than this giant, though, around 10 to 11 feet long. By far their most noticeable characteristic is their heads – they all have a wide, flat head that extends out past their body to look somewhat like a flattened hammer.
Their eyes and nostrils are at the tips of the extensions, allowing them to thoroughly scan the oceans for food. The different kinds of hammerheads vary in several ways, including size, distribution, and the shape of their hammers. The scalloped hammerhead has a wavy edge along the front of its head, while the smooth hammerhead has – you guessed it – a smooth edge. The great hammerhead is the largest, but has only 2 distinct bumps along the edge of its hammer. The bonnethead shark is relatively small, around 3 feet long, with a very smooth and rounded head. The smalleye hammerhead is very poorly understood. It has very small eyes relative to other hammerheads, hence the name. However, it also goes by the name golden hammerhead, because it is a really unusual golden color.
Whatever their differences, though, hammerheads all have one thing in common – their big, flat heads. It's very strange, don’t you think? What possible advantage could having a ridiculous looking head afford the shark? Well, actually, there are several advantages to it. One advantage is that it allows a very large area for the sensory organs that help it detect its prey. Called ampullae of Lorenzini, these are electrolocation sensory pores that help detect the electromagnetic fields put out by living organisms that the shark might eat. Popular prey for the hammerhead includes fish, crustaceans, and stingrays (apparently a favorite of the great hammerhead). Not only does the increased surface area for their electrolocation sensory pores help them hunt better, their nasal passages are much larger, too, giving them better smelling ability. So I already knew that. But here’s what I recently learned that I think is really neat. The hammerhead also helps the shark maneuver. The wide, flat surface of the head allows them to turn very tightly without losing stability. In addition, the head provides the shark with a lot of lift as it swims, much as a wing provides lift for a plane.
So, a wide head gives better hunting and better swimming. All in all, I'd say that's pretty smart.
Now, this may not be the most groundbreaking discovery ever – that the hammers of hammerhead sharks help them swim more efficiently. But I think there is a very important principle at work in my discovery that there was more to the hammerhead that I had previously known. There are so many things in the world that I think I know the answer to. But when I dig a little deeper, I find that there is always something new that I can learn. And that is the greatest thing about science!
The hammerhead shark picture was taken from:
http://www.sharkdiving.us/images/hammerhead/01.jpg
There are 9 different kinds of hammerhead sharks currently known – scalloped, great, smooth, whitefin, scalloped bonnethead, squarehead, scoophead, shovelhead and smalleye. The great hammerhead is the biggest, capable of reaching up to 20 feet long. Most of them are much smaller than this giant, though, around 10 to 11 feet long. By far their most noticeable characteristic is their heads – they all have a wide, flat head that extends out past their body to look somewhat like a flattened hammer.
Their eyes and nostrils are at the tips of the extensions, allowing them to thoroughly scan the oceans for food. The different kinds of hammerheads vary in several ways, including size, distribution, and the shape of their hammers. The scalloped hammerhead has a wavy edge along the front of its head, while the smooth hammerhead has – you guessed it – a smooth edge. The great hammerhead is the largest, but has only 2 distinct bumps along the edge of its hammer. The bonnethead shark is relatively small, around 3 feet long, with a very smooth and rounded head. The smalleye hammerhead is very poorly understood. It has very small eyes relative to other hammerheads, hence the name. However, it also goes by the name golden hammerhead, because it is a really unusual golden color.Whatever their differences, though, hammerheads all have one thing in common – their big, flat heads. It's very strange, don’t you think? What possible advantage could having a ridiculous looking head afford the shark? Well, actually, there are several advantages to it. One advantage is that it allows a very large area for the sensory organs that help it detect its prey. Called ampullae of Lorenzini, these are electrolocation sensory pores that help detect the electromagnetic fields put out by living organisms that the shark might eat. Popular prey for the hammerhead includes fish, crustaceans, and stingrays (apparently a favorite of the great hammerhead). Not only does the increased surface area for their electrolocation sensory pores help them hunt better, their nasal passages are much larger, too, giving them better smelling ability. So I already knew that. But here’s what I recently learned that I think is really neat. The hammerhead also helps the shark maneuver. The wide, flat surface of the head allows them to turn very tightly without losing stability. In addition, the head provides the shark with a lot of lift as it swims, much as a wing provides lift for a plane.
So, a wide head gives better hunting and better swimming. All in all, I'd say that's pretty smart.
Now, this may not be the most groundbreaking discovery ever – that the hammers of hammerhead sharks help them swim more efficiently. But I think there is a very important principle at work in my discovery that there was more to the hammerhead that I had previously known. There are so many things in the world that I think I know the answer to. But when I dig a little deeper, I find that there is always something new that I can learn. And that is the greatest thing about science!
The hammerhead shark picture was taken from:
http://www.sharkdiving.us/images/hammerhead/01.jpg
Friday, February 15, 2008
Go dog, go!
I’ll freely admit – I love pets. I’ve written about our cats before several times, and though we don’t have a dog right now, we’d love to get one in the future. In fact, one of my and my husband’s favorite activities every February is to follow the goings-on at the Westminster Kennel Club dog show. For those of you who don’t know, the Westminster Kennel Club dog show is the second longest continuously held sporting event in America (just one year behind the Kentucky derby). It is organized by the Westminster Kennel Club, America’s oldest organization dedicated to the sport of purebred dogs. Every February, dogs from over 150 breeds from around the world descend on New York to compete against each other, trying to be the dog that best matches the ideal standards of their particular breed. And we love to learn about all the different breeds of dogs! From giant St. Bernards to tiny Chihuahuas, from skinny Whippets to stocky English Bulldogs, from active Border Collies to pampered Pomeranians, domesticated dogs are a highly variable group, coming in all shapes, sizes, colors, features and temperments. In fact, domesticated dogs are the most highly variable mammal on the planet!
The domesticated dog, also known as Canis lupus familiaris, is a domesticated subspecies of the wolf. According the DNA evidence, the wolves that gave way to modern domesticated dogs began diverging from other wolves over 100,000 years ago; these wolves gave way to dogs some time later. (The exact time is disputed, and ranges anywhere from 15,000 to 100,000 years ago). Over time, dogs have diverged from each other in appearance because humans have selectively bred them to enhance for the traits they want. Let me give you a few examples of features that you might think are totally useless, but are actually integral to the dog’s purpose:
Corgis have extremely short legs relative to their body size. These dogs are particularly well-designed for herding cattle. Their short legs mean that when the cows kick, the dogs don’t get hit – they duck right under.
Daschunds also have short legs, but unlike corgis, their bodies are small and wiry. This is so they can crawl into dens and hunt out badgers, foxes and rabbits. This goes hand in hand with their tenacious and persistent (aka prone to barking) personalities.
Bloodhounds are extremely wrinkly dogs. Their faces seem to have about twice as much skin as they actually need! The reason for this is simple – the extra folds help funnel scents in from the air to the nasal passages of the hound. This allows them to be among the most sensitive scent hounds around – under optimal conditions, they can smell as few as 1 or 2 human skin cells.
Chesapeake Bay Retrievers are uniquely adapted to a watery life. Their coats are in 2
layers – a harsh outer coat and a dense woolly undercoat, both of which are oily and water-repellant. In addition, their hindquarters are especially strong and their back toes webbed, to allow for better paddling ability. All of this is very useful to the Chesapeake Bay Retriever, who was bred to retrieve fallen ducks from the frigid waters around the Chesapeake Bay when their masters were hunting. These dogs have been known to retrieve up to 200 ducks a day for their owners!
Bull
mastiffs are big, broad, stocky dogs. They have barrel-like chests and very thick skulls. This makes them well-suited for their original purpose – finding and immobilizing poachers by knocking them over and pinning them to the ground.
But here’s something interesting - despite the many unusual traits that these and all dogs have, dogs are not particularly genetically diverse. They retain the same basic characteristics of their ancestors – sharp teeth, strong jaws, powerful muscles, fused wristbones, and a cardiovascular system that supports both sprinting and endurance running. There are a few genetic distinctions that we know about among dogs breeds. For example, scientists have discovered that large dogs and small dogs have differences in a gene called insulin growth factor 1 (IGF-1). The IGF-1 gene of small dogs (like Chihuahuas and Pomeranians) tends to be of one variety, which is different from the IGF-1 gene of large dogs (like St. Bernards and Irish Wolfhounds). And while there are other genetic differences known to exist between breeds, scientists do not really know how those differences correlate with the different appearances of the dogs. So most of the differences may be primarily superficial – skin-deep, as opposed to DNA-deep.
And on a final note, this year’s Westminster Kennel Club dog show was particularly enjoyable. The winner of best in show was a 15-inch beagle named Uno. The beagle just happens to be one of my favorite breeds of all time, so I was really happy. How could you not love a face like this?
The following images were used in this entry:
Pembroke Welsh Corgi: http://www.dogbreedinfo.com/images10/PembrokeLucy2.jpg
Daschund: http://www.justusdogs.com.au/images/daschund.jpg
Bloodhound: http://www.greatdogsite.com/admin/uploaded_files/thumbnails/
bloodhound333x_1190777749500.jpg
Chesapeake Bay Retriever: http://www.dkimages.com/discover/previews/793/
75023959.JPG
Bullmastiff: http://www.dogbreedinfo.com/images16/BullmastiffShirley1
halfStand.JPG
Beagle: http://blog.mlive.com/kzgazette/2008/02/large_Uno.jpg
The domesticated dog, also known as Canis lupus familiaris, is a domesticated subspecies of the wolf. According the DNA evidence, the wolves that gave way to modern domesticated dogs began diverging from other wolves over 100,000 years ago; these wolves gave way to dogs some time later. (The exact time is disputed, and ranges anywhere from 15,000 to 100,000 years ago). Over time, dogs have diverged from each other in appearance because humans have selectively bred them to enhance for the traits they want. Let me give you a few examples of features that you might think are totally useless, but are actually integral to the dog’s purpose:
Corgis have extremely short legs relative to their body size. These dogs are particularly well-designed for herding cattle. Their short legs mean that when the cows kick, the dogs don’t get hit – they duck right under.
Daschunds also have short legs, but unlike corgis, their bodies are small and wiry. This is so they can crawl into dens and hunt out badgers, foxes and rabbits. This goes hand in hand with their tenacious and persistent (aka prone to barking) personalities.
Bloodhounds are extremely wrinkly dogs. Their faces seem to have about twice as much skin as they actually need! The reason for this is simple – the extra folds help funnel scents in from the air to the nasal passages of the hound. This allows them to be among the most sensitive scent hounds around – under optimal conditions, they can smell as few as 1 or 2 human skin cells.Chesapeake Bay Retrievers are uniquely adapted to a watery life. Their coats are in 2
layers – a harsh outer coat and a dense woolly undercoat, both of which are oily and water-repellant. In addition, their hindquarters are especially strong and their back toes webbed, to allow for better paddling ability. All of this is very useful to the Chesapeake Bay Retriever, who was bred to retrieve fallen ducks from the frigid waters around the Chesapeake Bay when their masters were hunting. These dogs have been known to retrieve up to 200 ducks a day for their owners!Bull
mastiffs are big, broad, stocky dogs. They have barrel-like chests and very thick skulls. This makes them well-suited for their original purpose – finding and immobilizing poachers by knocking them over and pinning them to the ground.But here’s something interesting - despite the many unusual traits that these and all dogs have, dogs are not particularly genetically diverse. They retain the same basic characteristics of their ancestors – sharp teeth, strong jaws, powerful muscles, fused wristbones, and a cardiovascular system that supports both sprinting and endurance running. There are a few genetic distinctions that we know about among dogs breeds. For example, scientists have discovered that large dogs and small dogs have differences in a gene called insulin growth factor 1 (IGF-1). The IGF-1 gene of small dogs (like Chihuahuas and Pomeranians) tends to be of one variety, which is different from the IGF-1 gene of large dogs (like St. Bernards and Irish Wolfhounds). And while there are other genetic differences known to exist between breeds, scientists do not really know how those differences correlate with the different appearances of the dogs. So most of the differences may be primarily superficial – skin-deep, as opposed to DNA-deep.
And on a final note, this year’s Westminster Kennel Club dog show was particularly enjoyable. The winner of best in show was a 15-inch beagle named Uno. The beagle just happens to be one of my favorite breeds of all time, so I was really happy. How could you not love a face like this?
The following images were used in this entry:
Pembroke Welsh Corgi: http://www.dogbreedinfo.com/images10/PembrokeLucy2.jpg
Daschund: http://www.justusdogs.com.au/images/daschund.jpg
Bloodhound: http://www.greatdogsite.com/admin/uploaded_files/thumbnails/
bloodhound333x_1190777749500.jpg
Chesapeake Bay Retriever: http://www.dkimages.com/discover/previews/793/
75023959.JPG
Bullmastiff: http://www.dogbreedinfo.com/images16/BullmastiffShirley1
halfStand.JPG
Beagle: http://blog.mlive.com/kzgazette/2008/02/large_Uno.jpg
Thursday, February 7, 2008
More cool images from outer space
I recently wrote about how 2 of Saturn’s lesser-known moons were recently shown to look astonishingly like flying saucers. (“Saturn’s flying saucers” from January 11, 2008.) Well, it looks like NASA is at it again. They’ve just released pictures of the planet Mercury, showing scientists a side of the planet never before seen by human eye.
Mercury is the smallest planet in our solar system (now that Pluto is no longer considered a planet, of course). It’s about one-third the size of Earth, with a diameter of around 3000 miles. (That’s roughly the distance from Los Angeles to Maine.) Being closest to the sun, Mercury has a very rapid orbit – it circles the sun once every 88 earth days. It doesn’t have a normal orbit, though, it has an elliptical one. The distance from the sun to the surface of Mercury varies from 28 million to 43 million miles. While there was much speculation some years ago as to why Mercury has such an eccentric orbit (including the theory that there was another planet even closer to the sun that was tugging on it), it now appears that this elliptical orbit is explained in Einstein’s General Theory of Relativity. Despite the fact that it orbits the sun very rapidly, it rotates on its axis relatively slowly. Mercury only rotates 3 times for every 2 orbits that it makes. (This would make for some very odd sunrises and sunsets on the surface!)
A lot of interesting comparisons can be made between Mercury and Earth. Both planets have similar densities. Also, both planets have similar cores made of iron. However, Mercury’s iron core is much larger than ours - it seems to make up around 42% of the volume of the planet, and is at least partly liquid. Like Earth, the core of Mercury is surrounded by a rocky mantle and crust; however, Mercury’s mantle and crust is much smaller than our own, coming in at approximately 370 miles thick. This crust is highly cratered, and actually looks a lot like the surface of our moon. Both Mercury and Earth also have magnetic fields (of the 4 rocky planets, they are the only 2 to have one.) Mercury might have even had an atmosphere, except for the fact that it is so close to the sun - its atmosphere is constantly getting blasted away by solar wind. Being so close to the sun has other consequences, too. Temperatures at the equator have an 1100 degree Fahrenheit difference between day and night – and despite the possibility of extreme heat, there is evidence of the existence of ice at the poles.
Mercury is visible from the surface of Earth, but just barely. It’s hard to see because it stays so close to the sun; this makes it hard to see except at twilight and dawn. In fact, about the only information we had until this year about the surface of Mercury came from NASA’s Mariner 10 spacecraft, which mapped about 40% of the planet’s surface in 3 fly-bys in the 1970s. But here’s the odd thing about the Mariner 10 mission. The combination of Mercury’s elliptical orbit and its slow rotation means that the same side of Mercury is always illuminated by sunlight when it is closest to the sun. So that’s the only side that the Mariner 10 was able to see in its pictures! That means that there was an entire half of the planet we’d never seen.
So, on August 3, 2004, NASA launched the MESSENGER spacecraft to do a detailed mapping of Mercury’s surface. (MESSENGER stands for Mercury Surface, Space Environment, Geochemistry and Ranging.) MESSENGER will make 3 flybys of the planet over the next 3 years before it settles in to a stable orbit around it. During those passes, the spacecraft will pass within 124 miles of the surface, allowing for some highly detailed images. And the first set of pictures, released in January, did not disappoint.
I think my favorite image is the giant spider crater. It’s a massive crater with faint lines
radiating out from the center of it, kind of like a squished spider. Scientists think that this may be the remnants of a volcano. There are also other neat images, though. For example, there is one taken near Mercury’s terminator – the line between the side of the planet lit by sunlight and the side in darkness. This image shows a vast plain of craters, which are enhanced because of the long shadows that exist at the terminator. And another shows a double ringed crater – it actually looks kind of like a doughnut on the surface. Scientists hope that these images will allow them to better understand the physical properties of Mercury, as well as its geological history. (For example, whether there has been volcanic activity on the planet.)
I highly encourage everyone to check out the website of the MESSENGER mission. You can see all of the images I’ve described (this is where I got the spider crater picture), as well as others that will be released as the spacecraft does more flybys. (The next one is scheduled for October of this year.)
http://messenger.jhuapl.edu/index.php
Mercury is the smallest planet in our solar system (now that Pluto is no longer considered a planet, of course). It’s about one-third the size of Earth, with a diameter of around 3000 miles. (That’s roughly the distance from Los Angeles to Maine.) Being closest to the sun, Mercury has a very rapid orbit – it circles the sun once every 88 earth days. It doesn’t have a normal orbit, though, it has an elliptical one. The distance from the sun to the surface of Mercury varies from 28 million to 43 million miles. While there was much speculation some years ago as to why Mercury has such an eccentric orbit (including the theory that there was another planet even closer to the sun that was tugging on it), it now appears that this elliptical orbit is explained in Einstein’s General Theory of Relativity. Despite the fact that it orbits the sun very rapidly, it rotates on its axis relatively slowly. Mercury only rotates 3 times for every 2 orbits that it makes. (This would make for some very odd sunrises and sunsets on the surface!)
A lot of interesting comparisons can be made between Mercury and Earth. Both planets have similar densities. Also, both planets have similar cores made of iron. However, Mercury’s iron core is much larger than ours - it seems to make up around 42% of the volume of the planet, and is at least partly liquid. Like Earth, the core of Mercury is surrounded by a rocky mantle and crust; however, Mercury’s mantle and crust is much smaller than our own, coming in at approximately 370 miles thick. This crust is highly cratered, and actually looks a lot like the surface of our moon. Both Mercury and Earth also have magnetic fields (of the 4 rocky planets, they are the only 2 to have one.) Mercury might have even had an atmosphere, except for the fact that it is so close to the sun - its atmosphere is constantly getting blasted away by solar wind. Being so close to the sun has other consequences, too. Temperatures at the equator have an 1100 degree Fahrenheit difference between day and night – and despite the possibility of extreme heat, there is evidence of the existence of ice at the poles.
Mercury is visible from the surface of Earth, but just barely. It’s hard to see because it stays so close to the sun; this makes it hard to see except at twilight and dawn. In fact, about the only information we had until this year about the surface of Mercury came from NASA’s Mariner 10 spacecraft, which mapped about 40% of the planet’s surface in 3 fly-bys in the 1970s. But here’s the odd thing about the Mariner 10 mission. The combination of Mercury’s elliptical orbit and its slow rotation means that the same side of Mercury is always illuminated by sunlight when it is closest to the sun. So that’s the only side that the Mariner 10 was able to see in its pictures! That means that there was an entire half of the planet we’d never seen.
So, on August 3, 2004, NASA launched the MESSENGER spacecraft to do a detailed mapping of Mercury’s surface. (MESSENGER stands for Mercury Surface, Space Environment, Geochemistry and Ranging.) MESSENGER will make 3 flybys of the planet over the next 3 years before it settles in to a stable orbit around it. During those passes, the spacecraft will pass within 124 miles of the surface, allowing for some highly detailed images. And the first set of pictures, released in January, did not disappoint.
I think my favorite image is the giant spider crater. It’s a massive crater with faint lines
radiating out from the center of it, kind of like a squished spider. Scientists think that this may be the remnants of a volcano. There are also other neat images, though. For example, there is one taken near Mercury’s terminator – the line between the side of the planet lit by sunlight and the side in darkness. This image shows a vast plain of craters, which are enhanced because of the long shadows that exist at the terminator. And another shows a double ringed crater – it actually looks kind of like a doughnut on the surface. Scientists hope that these images will allow them to better understand the physical properties of Mercury, as well as its geological history. (For example, whether there has been volcanic activity on the planet.)I highly encourage everyone to check out the website of the MESSENGER mission. You can see all of the images I’ve described (this is where I got the spider crater picture), as well as others that will be released as the spacecraft does more flybys. (The next one is scheduled for October of this year.)
http://messenger.jhuapl.edu/index.php
Tuesday, February 5, 2008
Mmmm…. Tastes good!
When you put something in your mouth tonight for dinner, a complex array of flavors may await you. You might not like all of the flavors, of course! But you can taste them, nonetheless. Have you ever wondered how?
Taste is a chemical sense. In that regard, it is similar to the sense of smell. Both taste and smell give us information about the chemical nature of our surroundings – taste giving us information about the chemical nature of what we’re about to eat, and smell giving us information about the chemical composition of the air we’re breathing. The senses of taste and smell are, in fact, closely related. Actually, the concept of flavor is really a combination of the taste, smell and texture of a substance. You’ve probably experienced how food tastes much more bland when you have a cold and can’t smell it. That’s because half of your ability to sense the flavor is lost when your nose is stuffy.
You might know that we have long believed to have only 4 basic taste sensations in our mouths -bitter, sweet, salty and sour. However, recent evidence seems to indicate that there may be 1 more thing we can taste – it’s called umami, or savoriness. Umami is the taste of non-salty flavorings like MSG. The combination of all 5 taste sensations provides the taste of any given substance. And these taste sensations are controlled by your tongue.
The tongue is a very rough, ridged surface, containing ridges and valleys called papillae. There are 4 types of papillae, 3 of which contain taste buds. Taste buds are onion-shaped groupings of 50 to 100 taste cells that protrude up into the surface of the papillae. When food is dissolved by the saliva in your mouth, it breaks up into different chemicals, which interact with different proteins on the surface of the taste cells. These proteins are called taste receptors.
The bitter taste receptors are a family of 30 or so related proteins called T2Rs (identified in 2000). Sweet taste receptors are combinations of T1R2 and T1R3 proteins, while umami is tasted by combinations of T1R1 and T1R3 proteins (all found in 2003). All of these proteins function in a similar manner. When triggered by their chemical, they change other proteins inside the cell, ultimately resulting in the transmission of a message of bitterness, sweetness or savoriness to the brain. Nothing passes in or out of the taste cells with these taste proteins.
There is currently only 1 candidate sour receptor protein, called PKD2L1 (discovered in 2006). This protein acts in a different way. Sour tastes are usually acidic, thus they contain hydrogen ions. These hydrogen ions block the channels for other ions (such as potassium). As a result, the ion concentrations in the taste cells change, which results in a sour signal being sent to the brain. While the salty receptor protein is currently unknown, it is believed that it probably allows sodium ions into the cell. This increase in sodium ions would result in the transmission of a salty signal to the brain. For all of these taste receptors, their underlying mechanism is the same – changing ion concentrations results in different taste signals being sent from the taste cells to the brain.
So now that these signals have been sent to the brain, the next challenge is for the brain to decode them. And here’s where we get to the real mystery of it. We don’t really understand how our brain interprets the signals that we get from our taste buds. In fact, the sensations of taste and smell are both really poorly understood at the levels of our brain. So unfortunately, I can’t tell you how that part works. Maybe someday we’ll have a better understanding of it!
Until then, all I can do is wish that you get to taste something you really enjoy today. (For me, that would definitely be chocolate…)
Taste is a chemical sense. In that regard, it is similar to the sense of smell. Both taste and smell give us information about the chemical nature of our surroundings – taste giving us information about the chemical nature of what we’re about to eat, and smell giving us information about the chemical composition of the air we’re breathing. The senses of taste and smell are, in fact, closely related. Actually, the concept of flavor is really a combination of the taste, smell and texture of a substance. You’ve probably experienced how food tastes much more bland when you have a cold and can’t smell it. That’s because half of your ability to sense the flavor is lost when your nose is stuffy.
You might know that we have long believed to have only 4 basic taste sensations in our mouths -bitter, sweet, salty and sour. However, recent evidence seems to indicate that there may be 1 more thing we can taste – it’s called umami, or savoriness. Umami is the taste of non-salty flavorings like MSG. The combination of all 5 taste sensations provides the taste of any given substance. And these taste sensations are controlled by your tongue.
The tongue is a very rough, ridged surface, containing ridges and valleys called papillae. There are 4 types of papillae, 3 of which contain taste buds. Taste buds are onion-shaped groupings of 50 to 100 taste cells that protrude up into the surface of the papillae. When food is dissolved by the saliva in your mouth, it breaks up into different chemicals, which interact with different proteins on the surface of the taste cells. These proteins are called taste receptors.
The bitter taste receptors are a family of 30 or so related proteins called T2Rs (identified in 2000). Sweet taste receptors are combinations of T1R2 and T1R3 proteins, while umami is tasted by combinations of T1R1 and T1R3 proteins (all found in 2003). All of these proteins function in a similar manner. When triggered by their chemical, they change other proteins inside the cell, ultimately resulting in the transmission of a message of bitterness, sweetness or savoriness to the brain. Nothing passes in or out of the taste cells with these taste proteins.
There is currently only 1 candidate sour receptor protein, called PKD2L1 (discovered in 2006). This protein acts in a different way. Sour tastes are usually acidic, thus they contain hydrogen ions. These hydrogen ions block the channels for other ions (such as potassium). As a result, the ion concentrations in the taste cells change, which results in a sour signal being sent to the brain. While the salty receptor protein is currently unknown, it is believed that it probably allows sodium ions into the cell. This increase in sodium ions would result in the transmission of a salty signal to the brain. For all of these taste receptors, their underlying mechanism is the same – changing ion concentrations results in different taste signals being sent from the taste cells to the brain.
So now that these signals have been sent to the brain, the next challenge is for the brain to decode them. And here’s where we get to the real mystery of it. We don’t really understand how our brain interprets the signals that we get from our taste buds. In fact, the sensations of taste and smell are both really poorly understood at the levels of our brain. So unfortunately, I can’t tell you how that part works. Maybe someday we’ll have a better understanding of it!
Until then, all I can do is wish that you get to taste something you really enjoy today. (For me, that would definitely be chocolate…)
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