This is a sketch from the British comedy show "That Mitchell and Webb Look." Yay for British humor :-)
Saturday, July 31, 2010
Sandy Solutions
Apparently it is a wonderful day for astronomical news. Who knew? I'm one of those people who loves to read about astronomy (particularly planetary science) but never actually goes outside and looks up. Anyway, this next story I found in a couple of places and thought it was pretty interesting.
Way back in 1655 Christian Huygens discovered the moon Titan orbiting around Saturn. In fact, it is Saturn's largest moon and for a long time it was thought to be the largest moon in the solar system. After all, it is bigger than the planet Mercury. Alas, it was then realized we had based that judgement by measuring from the center to the edge of the atmosphere instead of from the center to the surface. But a big ole thick atmosphere on a moon is pretty neat all in itself. The moon runs about -180 degrees Celsius (-290 degrees Fahrenheit), cold enough for liquid methane to rain down and collect into lakes, rivers, and seas. Other parts of the surface, particularly the equatorial regions, are covered in giant sand dunes. These dunes are approximately 1 km (~0.5mi) wide, tens to hundreds of kilometers long, more than 100 m (300ft) high, and composed of organic hydrocarbons.
So lets take a look at a particular paradox that exhists on Titan. What we know about the rotation of planetary atmospheres plus data from the Huygens probe (which landed on Titan's surface) tells us that surface winds should go east to west. Then the Cassini spacecraft sent images of Titan's equatorial dunes which suggested that the winds were moving west to east. A new paper in Aeolian Research, and a related paper in Science, attempt to explain this phenomenon.
These papers propose that there are seasonal changes on Titan that reverse the wind patterns for a short period. The equinoxes appear to be particuarly important. Now it is easy to start thinking of other planets like you think of your own, but Saturn is a large planet to orbit around and it is very far away from the sun. One year on Titan is about 29 Earth years, and during that time the moon will have two equinoxes. These are times when the heat from the sun creates atmospheric upwellings, causing the winds to reverse and accelerate (kinda like monsoons on Earth). Short gusts of west-to-east winds occurring intermittently over two years are so strong that they transport the dunes' sand more effectively than the normal east-to-west winds, causing these reverse striations in the dunes.
Take a look through the articles:
Tokano, Tetsuya. (2010) Relevance of fast westerlies at equinox for the eastward elongation of Titan's dunes. Aeolian Research: In press. (DOI: 10.1016/j.aeolia.2010.04.003)
Lorenz, Ralph D. (2010) Winds of Change on Titan. Science: 329(5991), 519 - 520. (DOI: 10.1126/science.1192840)
and...
http://www.sciencedaily.com/releases/2010/07/100729205552.htm
(image credit: NASA/JPL)
So lets take a look at a particular paradox that exhists on Titan. What we know about the rotation of planetary atmospheres plus data from the Huygens probe (which landed on Titan's surface) tells us that surface winds should go east to west. Then the Cassini spacecraft sent images of Titan's equatorial dunes which suggested that the winds were moving west to east. A new paper in Aeolian Research, and a related paper in Science, attempt to explain this phenomenon.
These papers propose that there are seasonal changes on Titan that reverse the wind patterns for a short period. The equinoxes appear to be particuarly important. Now it is easy to start thinking of other planets like you think of your own, but Saturn is a large planet to orbit around and it is very far away from the sun. One year on Titan is about 29 Earth years, and during that time the moon will have two equinoxes. These are times when the heat from the sun creates atmospheric upwellings, causing the winds to reverse and accelerate (kinda like monsoons on Earth). Short gusts of west-to-east winds occurring intermittently over two years are so strong that they transport the dunes' sand more effectively than the normal east-to-west winds, causing these reverse striations in the dunes.
Take a look through the articles:
Tokano, Tetsuya. (2010) Relevance of fast westerlies at equinox for the eastward elongation of Titan's dunes. Aeolian Research: In press. (DOI: 10.1016/j.aeolia.2010.04.003)
Lorenz, Ralph D. (2010) Winds of Change on Titan. Science: 329(5991), 519 - 520. (DOI: 10.1126/science.1192840)
and...
http://www.sciencedaily.com/releases/2010/07/100729205552.htm
(image credit: NASA/JPL)
The Sky is Falling
Are you ready for the Perseid meteor shower? This year's shower occurs on August 11-14, and apparently it is supposed to be one of the best in recent years. Check out MeteorWatch and their Twitter feed for a countdown and more info.
Friday, July 30, 2010
Ants on High
You're a scientist, and you're thiiiis big. Right, ok, nevermind. How do you design an experiment to see how ants measure distance?
I'll give you a second to think on it...
You're gonna love this one. So, it is known that ants use the sun kinda like a compass so they know which direction they are going, and they have a component in their brains which acts as a body clock so they know how long they've been gone. Well, this paper published in the Journal of Experimental Biology shows how ants count their steps in order to judge distance.
In the study, researchers used Desert ants (Cataglyphis fortis) from a field site near Maharès, Tunisia. First, they trained the ants (Fun Job #1: Training ants) to walk a distance of 10 m in a linear alloy channel from their nest entrance to a feeder due south and back again. All the ants got marked with a color (Fun Job #2: Painting ants) and their leg lengths were manipulated to test their ant-odometers. And here's where we get creative. The researchers wanted to both shorten, lengthen, and keep the same various ants' legs, altering their stride length. To shorten, tarsal segments were removed or the legs were severed mid-tibia (snip, snip). To lengthen the legs, hairs from a pig were individually Superglued onto the end of each leg, extending it by about 2-3 mm (Fun Job #3: Supergluing itty-bitty hairs to itty-bitty ant legs). Oh yeah, ants on stilts!! They allowed the ants to go from their nest to the feeder, there they altered their leg length, allowed them to pick up some food, and then let them try to find their way home. Using a high-speed camera, the ants were filmed as they walked down the channel (Fun Job #4: Going through high speed video frame by frame counting ant steps). The results showed that ants that had their legs lengthened overshot their nests, and ants that had their legs shortened didn't walk far enough. If the ants-on-stilts or ants-with-stumps went to the feeder from the nest and then back again they judged the distance correctly, showing that they have the ability to quickly adjust to their new leggy situation. The paper itself goes over supporting/rejecting various hypotheses as to why, but as I'm just focusing on the fact that they put ants on stilts I'll leave the discussion section of the paper for you to read.
Here's your reference:
Wittlinger, Matthias, Rüdiger Wehner and Harald Wolf (2007) The desert ant odometer: a stride integrator that accounts for stride length and walking speed. Journal of Experimental Biology: 210, 198-207. (DOI: 10.1242/jeb.02657) (or this Link)
(image credit to the Max Planck Institute for Chemical Ecologists, Markus Knader)
Saturday, July 24, 2010
Friday, July 16, 2010
On the Rails
High speed trains. You ask me, I say they are a wonderful idea as long as someone is willing to pony up the money to build the infrastructure. That money thing seems to be the problem in the U.S. at least (how many light rail laws have passed with no actual trains being built?). Anyway, take a look at this proposed train in Britain.
The Mercury Train is a design of Paul Priestman and Priestmangoode, the designer of Britain's widely used Virgin Pendolino train cars. Priestman is determined to convince Britain that a high-speed, high-tech train such as this is the key to achieving sustainable, low-carbon transportation which will invigorate the economy.
The train is a 400 meter long double-decker that travels at 225 mph. Such speed is thanks in part to the extended nose of the train.It houses commuter seats outfitted with entertainment systems, private compartments, a play area for kids, and a bar and lounge.
The Mercury Train is a design of Paul Priestman and Priestmangoode, the designer of Britain's widely used Virgin Pendolino train cars. Priestman is determined to convince Britain that a high-speed, high-tech train such as this is the key to achieving sustainable, low-carbon transportation which will invigorate the economy.The train is a 400 meter long double-decker that travels at 225 mph. Such speed is thanks in part to the extended nose of the train.It houses commuter seats outfitted with entertainment systems, private compartments, a play area for kids, and a bar and lounge.Here are some links:
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