A Short Biography of the Foucault Pendulum.

When you walk into the Wiess Energy Hall, the very first thing you see is our Foucault pendulum.

It is a metal ball suspended by a cable that swings back and forth encircled by pegs. Children and adults will run through the rest of the museum, reach the pendulum, and wait with baited breath to watch a peg topple. When one of the pegs finally falls, you can hear a cheer erupt from the area. It is one of the most memorable parts of the museum. As the pendulum swings, it moves clockwise knocking down pegs as the Earth turns. It swings back and forth, back and forth (you are getting sleepy).

 Foucault Pendulum at the Houston Museum of Natural Science

It is interesting to sit around the pendulum and listen to people try to explain it.

Some will talk about how it is a clock.  Others will put the time between pegs being knocked down between 10 minutes and 1 hour.  Our pendulum knocks down a peg on an average of every fifteen minutes. While the pendulum looks like it rotates around the circle, it is the Earth that is rotating and the pendulum that just swings. The pendulum is a visualization of a rotating Earth. To describe it in a different way, T = 24/sin q where T equals the amount of time to make one complete revolution and q is the latitude of the pendulum. At least that’s what Foucault said.

photo credit: monkeymanforever

Leon Foucault was born in Paris (France, not Texas) on September 18, 1819.

As a young boy he did not show an inclination towards science or study.  In fact his teacher considered him lazy because he did not turn in his work. He did, however, enjoy building mechanical devices, such as a small steam engine and a telegraph, and tinkering.  He entered medical school to become a surgeon, but found that he fainted at the sight of blood.  Instead of becoming a blindfolded surgeon, he switched to physics.

At the age of 25, not having learnt anything at school nor from book, enthusiastic about science but not about study, Léon Foucault took on the task of making the work of scientists understandable to the public and of passing judgment on the value to the work of leading men of science – J Bertrand, Éloge historique de Léon Foucault.

Foucault proved his worth in being able to take mathematical proofs and construct a mechanical proof, his pendulum being one of those.

He also constructed a device to prove that light moves slower through water than air. The mathematics describing the proof had been around for over a decade, but Foucault was the first to prove that it worked. His first pendulum on public display opened on February 3, 1851 in the Paris Observatory (again France, not Texas). Instead of knocking down pins as the pendulum moved, the first Foucault pendulum drew in sand.  He also invented the gyroscope, which stays in place as the Erath moves around it. This invention has proved essential for planes, space craft, and even the Hubble Telescope.

photo credit: NASA Goddard Photo and Video

After he came to power, Napoleon III, an amateur scientist, created a job for Foucault at the newly named Imperial Observatory. There, Foucault developed his knife edge test to measure the conic shape of mirrors. This led to a more constant quality of lenses for use in telescopes.  He died on February 11, 1868 from multiple sclerosis.  His legacy lives on today.  He has an asteroid named in his honor. But he is honored around the world by his plethora of pedula that swing to and fro, showing people that the Earth keeps on spinning.

The Celestial Sea

As you look up into a November sky right at nightfall, you may notice fewer bright stars than at other times of year. No, it’s not just the glare from Houston hiding most of the stars from view–there really are fewer bright stars in the November evening sky than in, say, February or August. To understand why, you need to understand the shape of our galaxy itself.

photo credit: visualpanic

Our galaxy, the Milky Way, is a barred spiral galaxy.

Evidence indicates that the Milky Way, like many large galaxies, has a massive black hole at its center. A radio source designated Sagittarius A* could be the black hole itself. (The asterisk is part of the name, which is “Sagittarius-A-star”). Surrounding this black hole is a central bulge where older (and thus redder) stars predominate.  The Bulge of our galaxy is not fully spherical but instead forms a bar a few thousand light years long.  Branching out from this bulge are spiral arms which contain younger (bluer) stars and dust clouds out of which brand new stars form.  Our solar system is about 26,000 light-years from the center to the edge, on the inside edge of the Orion Arm.  The Orion Arm, in turn, is but a spur of the much longer Perseus Arm.  The Milky Way is quite flat–over 100,000 light years wide but only 1,000 light years thick.

The flatness of the galaxy means that most of its stars are near a certain plane in space.  Of course, the galaxy is much thicker than our solar system, so we see our stellar neighbors suurounding us on all sides.  The rest of the galaxy, extending off into the distance, appears to us as a hazy blur in the background, with individual stars (those fairly close to us) in the foreground.  That hazy blur looked like spilled milk to the ancient Greeks, thus the name ‘Milky Way.’  We see more stars near that plane than far from it.

What does this have to do with the dimness of a late November sky at dusk?

Imagine observing our flat galaxy from our vantage point on Earth. When we face into the galactic plane, we see more bright stars, because there are more stars in that direction.  When we face above or below that plane, we see fewer bright stars.

Face west at dusk in late November and early December, and you’ll notice an enormous triangle of three bright stars, all bright enough to appear even in skies lit by Houston.  These stars from the Summer Triangle, so called because it is up all night long from June through mid-August.  This Triangle is also directly in the plane of the Milky Way.  The constellation Sagittarius, which marks the center of the Galaxy, sets just after the Sun this time of year.  Therefore, if you trace a path approximately from the  point of sunset through the Summer Triangle, over to five stars in an ‘m’ shape in the North (that would be Cassiopeia, the Queen), and then over to the northeastern horizon.  This is the plane of the Milky Way across late autumn skies at dusk .

Turn to the south, and you face below the galactic plane (as we’ve arbitrarily defined ‘above’ and ‘below’).  Here is a vast region of sky almost void of bright stars.  One exception is Fomalhaut, low in the southeast at dusk tonight.  Also, Houstonians with a very clear southern horizon can see Achernar very, very low in the south on December evenings.  But that’s about it.  There are many fewer bright stars in this direction than towards the Summer Triangle.  By the way, the brilliant object in the east at dusk tonight, and high in the southeast as dusk in December, is Jupiter. It doesn’t count as a bright star for this sector of the sky.

The Celestial Sea

When ancient Mesopotamians looked up into the dim skies you see at dusk tonight, they imagined the Persian Gulf south of them extended up into the sky, forming a ‘Celestial Sea’.  They therefore placed many water-themed constellations in this part of the sky.  Zodiacal constellations here include Pisces, the Fish, and Aquarius, the Water-Carrier.  Even Capricornus, the Goat, has the tail of a fish because he originally represented Ea, the ancient Babylonian god of the waters.  Under Pisces is the sea monster Cetus, while Piscis Austrinus, the Southern Fish, drinks the water that Aquarius pours.  Eridanus, the River, rises in the southeast, flowing from Orion’s foot into this vast ‘sea.’

photo credit: paul (dex)

Contrast this vast, dim region with the much brighter swath of stars that rises in the east later this evening (9-10 pm in late November, earlier in December).  This region of sky includes the brilliant pattern Orion, the Hunter, as well as Sirius, the brightest star we ever see at night.    When these stars rise, we are beginning to face back into the plane of our galaxy, this time looking into our own arm of galaxy at the stars right ‘behind’ the Sun.  (This is why our arm of the Milky Way is called the Orion Arm.)  Winter evening skies are much brighter than those of late autumn.

Black Hills Institute

Today’s post is by Sami Mesarwi, a member of the Museum’s marketing staff who recently traveled to South Dakota to visit the Black Hills Institute.

If the company you work for had to send you on a business trip anywhere you wanted to go, where would it be?  Paris?  London?  Shanghai?  How about Hill City, South Dakota?  Probably wouldn’t be a first choice for too many out there… And while I would have said the same before my trip to the Black Hills Institute of Geologic Research (and I probably still wouldn’t be able to pass on Paris), this paleontological-Mecca should definitely be in the running for you dino-die-hards out there.

 The Black Hills Institute of Geological Research

I’ve always loved dinosaurs.

In fact, Michael Crichton’s Jurassic Park is still one of my all-time favorite books (I may have grown up thinking that Crichton’s logic used in the novel to try and resurrect dinosaurs using the DNA found in preserved mosquitoes, as well as amphibians to fill in the holes, was flawless, but I’ve come a long way since then).  So, going on this trip seemed like it was going to be quite enjoyable from the start.  Our mission was simple enough: to go up and get some photos of the fossils that will eventually be on display in the museum’s upcoming new paleontology hall, opening summer 2012.

A coworker and I took the trip up to South Dakota in April, a time when Houston weather had consistently already warmed up to 90+ degrees outside.  However, surprising to all of us on the trip, we were greeted by snow in South Dakota!  Even though it was April, it was a Winter Wonderland—the color of the snow that covered the ground literally blended in with the sky’s horizon. Needless to say, it was pretty cold.  But I was able to get some pretty nice still shots out of it.

 Winter Wonderland!

Day one of our trip to South Dakota was a whirlwind of sights and sounds from within the Black Hills Institute.

Everyone met up inside the Institute with the famed Peter Larson, the Yoda (though not quite as old) of casting fossils and of T. rex.  He gave us a brief history of his background and of the Institute while in the main lobby area, a who’s who of dinosaurs from several different eras.  In addition to the infamous SUE the T. rex, there were examples of Triceratops, Struthiomimus, Acrocanthosaurus, what seemed like an infinite amount of ammonites, and so much more, all filling an area about the size of an average backyard in the suburbs.  It was amazing—I’ve never seen so many dinosaurs in a compact area before.

 Pete Larson in the zone.
 The Black Hills Institute Showroom

Onwards we continued to the prepping areas (a separate building from the museum itself), showcasing a few dinosaurs in the development and mounting stages. Pete told us about several of the specimens we’d be getting here at HMNS, before all of the paleontologists on hand broke into a discussion about the immaculate condition some of the fossils were in (I can’t give away too much about what in particular we’re getting—you’ll just have to wait and see!).  Before this trip, I thought I could hold my ground pretty decently well in matters of dino-speak.  But boy was I wrong.  Being surrounded by so many accomplished and literally world-renowned paleontologists (including Pete Larson, Dr. Robert Bakker, and so many others) was really very exciting.  But also quite humbling.

Pete then took us to the casting/molding area, where several Black Hills employees were diligently working to create some very impressive casts of fossils that they had.  They poured the liquid silicone rubber into the two mold halves, and, with some of the smaller ones, fastened them together with—interestingly enough—Legos! Turns out those colorful, little building blocks aren’t just fun to play with, but are also way more practical than you would think…

 Pete Larson and Dr. Bob Bakker examining a recent find.

Our second (and final) day of the trip allowed for us to talk up close with Pete himself.

Pete told us all about the Black Hills Institute itself and how it came to be—in 1974, as an earth science supply house, providing teaching specimens for colleges and universities, before branching out into doing museum exhibits.  In fact, as Pete points out, the products coming out of the Black Hills Institute can be found on every continent in the world (though he was mindful to exclude Antarctica from the list—hardly as impressive now, if you ask me).  After he answered our countless questions, Pete allowed for us to roam around the Black Hills Institute at our leisure, getting some shots of whatever it is that we wanted.  We took still shots of some of the specimens that will be making an appearance in the new paleontology hall, as well as some of the stars of the show.

After that, we grabbed a quick lunch at the corner bistro before heading back home to Houston.  Though we did make a quick stop on the way back… As we were only about 15 miles away from Mount Rushmore, we went ahead and visited the famed monument on our way to the airport. Quite breathtaking, I must say!  To me, the tranquility of the park where the monument is located, coupled with the remarkable stature of the presidents whose faces are forever immortalized in the mountain’s façade, were equally as impressive to me as the mountain goat we saw.

 Mount Rushmore.

All in all, the trip to Hill City, South Dakota was so much cooler (both, literally and figuratively) than I originally anticipated.  While the city itself isn’t exactly the largest out there (population: 948), or the most exotic of your travel destinations, it should absolutely be a front-runner for all of you dino-enthusiasts out there.

Watching the River Flow

Water is important.

That’s a pretty self explanatory statement.  Not only do we need water (at least 8 cups a day), but we are mostly water (60% of us anyway).  It’s one of the indictors we look for in new planets to see if we can use it as future real estate. It’s cornucopia of resources can provide almost everything people need to survive. Animals and plants that grow and live in water can provide food and clothing.  Caves hollowed out by water can provide shelter. The prehistoric oceans provide an area to lay the foundation of hydrocarbons. Water can be drunk to satiate thirst.  The movement of water can power the machines of mankind.

 photo credit: kevin dooley

Man has always known he needs water. Water has always been present whether it comes freely from the skies or washes down in all its fury in a flood.  Agriculture brought about man’s first attempt to channel what water he had.  The landscape was literally remade to get the water to move where it was needed.  Deserts have been made to flower and flowering areas have been made into deserts.  As time went by, we were able to make the movement of water do more for us.  First it was used to help run simple machines, such as mills, where grain was ground into flour.  It was also used in mining, to bring the ore out of the mine, or used to power hammers at a forge.

Water power helped to start the next stage of technological development, the Industrial Revolution. Larger and larger factories were built on rivers to take advantage of the free energy that the flowing water offered them.  Unfortunately they also let the water carry off their excess and trash, making downstream a place to avoid.  While the Thames helped England become a technologic and mercantile titan, it also made the river undrinkable and became so foul that the House of Commons had to be abandoned for a while in the mid 19th century. Water was also the crucial part of steam power that allowed the transportation industry to remake itself from horse drawn carriages to trains and steamboats.

 photo credit: fairlightworks

Water is still vital today.

Most of electricity comes from burning fuels to create steam to move turbines.  Water is also crucially important for solar panels.  Water may sound like an odd thing for solar power to depend upon, but large scale solar thermal arrays can use twice as much water per mega watt hour as a coal fired plant.  Geothermal power plants use water the exact same way as coal fired plants; they heat it into steam and have it turn turbines (although the water could be replaced with other substances). Biomass needs water to grow.

And of course water is the essential part of hydropower.  Without water (hydro) hydropower would be impossible.  When most people think of hydropower they think of dams (this is where being fond of puns can get you into a lot of trouble, kids. Just leave those dam puns alone).  A dam works by controlling the flow of the water.  It constricts the area the water is trying to move through and uses that movement to turn the turbines.  Because the pathway is constricted, the water backs up and can form a lake (also called a reservoir).  This changes the local environment from a river to a lake. This can affect the local wildlife and lead to erosion downstream.  People (and history) can be affected by dam building as well.  Due to the building of the Aswan Dam in Egypt, over 150,000 people had to be relocated because they were in the flood plain created by the dam.  The Abu Simbel Temple was moved to higher ground as well.

Hydropower can also be generated by the flow of a river, the movement of the waves, and the tides (movement is electricity) and electricity is movement. It is also easy to transfer excess electrical generation into storage by pumping some of the water back upstream or back into the reservoir.

Electricity generated by hydropower accounted for nearly 7 % of our total U.S. electrical generation in 2010. Over half of the hydroelectricity comes from the 3 states on the West Cost; California, Oregon, and Washington.  While there has been a lot of development over the years, there is still the potential to add more hydroelectric sites and increase the electrical output by a 3rd.  However, the amount of electricity produced by hydroelectric generation varies from year to year with the water cycle.  If you have a year with less precipitation, the rivers may have less water; if the river slows, the amount of electricity is less. Most areas where a large scale hydroelectric plant would work have already been dammed up for use.  The future might be in small scale generators that would help communities near running water.

 photo credit: Perrimoon

All that to say water is, in fact, important.

We have to have it to live.  We have to have it for our energy production. It takes 10 gallons of water to make 1,000 kilowatt hours using natural gas as a fuel, up to 9,200 gallons for solar thermal and about 20,000 gallons for nuclear. So what happens when we start to run out of it?  I don’t mean that the water on the Earth will suddenly disappear.  It is in a mostly closed system and the water can’t go anywhere (except if water is used on a space ship outside the atmosphere).  What I mean is that on a planet that’s mostly water, only 3% of it is fresh water.  We can’t drink saltwater.  We can’t grow crops with saltwater.  In the coming decades we will have to manage what water we have well. There are ways to generate more fresh water.  Desalinization removes the salt from sea water, but it is energy intensive.  In some areas the excess removal of groundwater can cause subsidence.  This has been an issue in the Houston area. In the 70’s this led to the creation of a Harris Galveston Subsidence District, the only one of its kind in the USA, to monitor and regulate groundwater usage to prevent subsidence.

Water management will become increasingly important.

Good water management will make sure that both people and industries get the water they need. Communities all along waterways will have to work together to mange their resource.  Managed from the local level up we’ll be able to sail through any water crisis.