Wednesday, January 30, 2013


Saw this on Science is Awesome on Facebook.  I completely identify since this is how I do everything in my life!
I have to work on this.  Maybe tomorrow.

Tuesday, January 29, 2013

Legislative morons

I could probably have a weekly blog post on the stupidity of our elected officials.

Watch this short clip of Louisiana State Senator Mike Walsworth (R) questioning Darlene Reaves, a retired fourth-grade science teacher, during a hearing last April on SB 374 - a bill to repeal the infamous 2008 Lousiana Science Education Act (LSEA).

Wow!  A few comments.

There's nothing wrong with being ignorant of evolution (there are all kinds of topics I'm ignorant about), but there is definitely something wrong about being ignorant of a topic and then belittling people (people who know a lot more about it) with your arrogant stupidity.  How can these people call themselves Christians?  Isn't humility still a Christian virtue?  Dude, you're making Louisiana a laughing stock among educated people around the world who think you're a pompous dumbass (and they're right!).

Senator Walsworth is on the Louisiana State Senate Education Committee.  This moron has a voice in educating the children of Louisiana - the state that ranks 48/50 by the Statistical Research Center at the American Institute of Physics which studied how well U.S. schools are preparing students for science and engineering careers.

From his stupid questions (and, yes, there is such a thing as a stupid question despite what teachers told you in an attempt to make you feel better), the Senator makes it clear that he not only doesn't understand the concept of biological evolution, he doesn't understand how science works either.  Not surprising considering his background before becoming a State Senator was as a real estate developer (perfect background for serving on the Education Committee, don't you think?).

Darlene Reaves, the elementary school science teacher is too nice to this buffoon (although the expression on her face after he asks if any bacteria evolved into humans is great).  I would have called him on his idiotic question - "Are you serious Senator, is this what you believe evolutionary theory predicts?  I expect better of 4th graders!"

Also, if you'd like to read more about the very interesting experiment showing the evolution of  E. coli that Ms Reaves mentioned, here's a summary.

By the way, the 2008 Lousiana Science Education Act (LSEA) stipulates:

"The State Board of Elementary and Secondary Education, upon request of a city, parish, or other local public school board, shall allow and assist teachers, principals, and other school administrators to create and foster an environment within public elementary and secondary schools that promotes critical thinking skills, logical analysis, and open and objective discussion of scientific theories being studied including, but not limited to, evolution, the origins of life, global warming, and human cloning."

While there's nothing wrong with promoting "critical thinking skills, logical analysis, and open and objective discussion of scientific theories" - those are great things - singling out evolution, origin of life, global warming, and human cloning shows the political motivations of this bill.  Bills like this, introduced in states around the country by Republican legislators, have been used to introduce creationism and climate change denialism into public school classrooms.

To top it off, SB 374 died in the Education Committee after these hearings.  Apparently the State Senators in Louisiana want the children of Louisiana to be as stupid and ignorant as they are about science.

There is a hero in all of this, Google Zack Kopplin, a 19-year-old student who's been working for a couple of years now against this nonsense.

Monday, January 28, 2013

Awosting Falls

Temperatures rose to 40° F Sunday, with blue skies, so the family took a walk to Awosting Falls at Lake Minnewaska State Park (we bought a state park pass this year, so any excuse to use it is good).  The trail was a bit icy and slippery on the downhill sections which made for careful walking, but worth it for the beautiful view of the ice-coated waterfall.


Here I am with my daughter near the base of the falls.

I need to get out more in the winter!

Sunday, January 27, 2013

Telling time by lunar & solar cycles

Astronomy is one of the oldest sciences because it has practical applications.  For virtually all ancient cultures, one of those applications was time-keeping.

Imagine yourself back in time thousands of years ago.  You have no clocks or calendars.  How can you predict when winter will arrive (or spring)?  How about the time of year when aurochs migrate?  When do we travel to find ripe berries?  Being able to tell what time of year it was enhanced your chances of survival.  How do you keep track of time?

Well the answer is obvious if you simply watch the sky.  The sun rises and the sun sets.  The moon waxes from new to full and then wanes back to new.  Sunrise and sunset are sometimes further south (the time when it's cold and snowy and the sun low in the sky) and sunset and sunrise are sometimes further north (the time when it's warm and green and the sun high in the sky).  The stars and contellations visible in the sky, and when they rise and set, changes over the course of the seasons.

Let's look at one of those cycles.  One thing easy to observe are the phases of the moon and every ancient culture developed a lunar calendar.  We still use them today in modern times - they're the reason why religious holidays like Yom Kippur, Passover, Easter, and Ramadan always fall on different days of the year on our civil calendar.  The dates of these holidays are based on ancient lunar calendars.

The cycle of lunar phases is called the synodic month and lasts 29.53059 days (note that it's not an even number of days).

Another cycle which was obvious to all ancient cultures is the change in position of sunrise and sunset over the course of the year.  For, example, here in the Hudson Valley, if you go out and observe where the Sun rises each morning, you'll see the following in December, March, June, September, and December again.




In December, the Sun is rising toward the south and never gets high in the sky.  In March, the sunrise is almost due east.  By June, the Sun is rising toward the north and gets high in the sky.  In September, the sunrise position swings back toward rising in the east.  And, finally, when December rolls around again, the Sun is rising in the south.  Over and over again as each year passes with the changing seasons.

The time when the Sun rises (and sets) furthest in the south is the winter solstice.  The time when it rises (and sets) furthest in the north in the summer solstice.  The time when it rises (and sets) due east are the vernal (spring) and autumnal (fall) equinoxes.  If you wanted, you could erect some stones to mark these directions.

Like the lunar cycle, you can measure the time for this cycle (which is a year) but it's also not an even number of days.  This period of time is called the tropical year (from the Greek tropikos which means "to turn") and is 365.24163 days long.

Let's look for a relationship between these two cycles.

It turns out that nineteen tropical years:

   (365.24163 days/year) * (19 years) = 6,939.59097 days

How many synodic months are in 6,939.59097 days?

   (6,939.59097 days) / (29.53059 days/month) = 234.99669 months

Which rounds very closely to 235 months (there's about a 2.3 hour difference).

In other words, 235 synodic months is almost exactly 19 tropical years.   This is called the Metonic Cycle (another mouthful of a term is the Enneadecaeteris which is derived from the ancient Greek word εννεαδεκαετηρις, which means "nineteen years").

This cycle was named for Meton of Athens, a Greek mathematician who lived in the 5th century BC.  While Meton utilized this cycle for reforming the calendar at the time, it was know to the Babylonians in the 6th century BC who utilized it in their calendars as well.

So what do we get when we divide 235 months by 19 years?

   (235 months) / (19 years) = 12.36842 months/year

That's why years still have 12 months.  But, after a 12 synodic month year, you're left with 0.36842 of a month which is:

   (0.36842 months) * (29.53059 days/month) = 10.88 days

So you have roughly 11 extra days between a lunar year of 12 cycles of lunar phases and the solar year from solstice to solstice.  Most cultures dealt with these extra days by periodically inserting an extra month.

The traditional Jewish calendar, for example, has twelve months alternating between 29 and 30 days (averaging the 29.5 day lunar phase cycle).  But, because of those 11 extra days per year, they periodically add an extra month.  In years 3, 6, 8, 11, 14, 17, and 19 of the nineteen year Metonic cycle, they add a "leap month."  In normal years, Adar occurs around February/March before the vernal equinox, in leap months, Adar become Adar Bet (Adar 2) and the 30 day month of Adar Aleph (Adar 1) is added to the calendar.

Even our modern civil calendar, while no longer tied to lunar phases, still has 12 months in a year reflecting its derivation from older lunar-based calendar.  Months are longer than 29.5 days, however, to keep the calendar in sync with the tropical year (and therefore the seasons).

Let's look at the days in each month with respect to the average number of days in the synodic month of lunar phases:

What a surprise, the difference adds up to 11 days.  It still doesn't exactly match up which is why we periodically insert that extra day in February every four years.

I love watching the sky and seeing that change in lunar phases (it was a bright full January "Wolf Moon" out there last night) and the change in the position of the Sun.  I can already feel the days lengthening and the Sun moving higher in the sky as we move into February.  Very soon, we'll start to see some of the earliest signs of spring in the neverending dance of the Earth, Moon, and Sun.

Wednesday, January 23, 2013

March Comet?

Back in June, 2011, the Pan-STARRS telescope on top of Haleakala on the island of Maui in Hawaii detected a new comet with the forgettable name of C/2011 L4 (PANSTARRS).

Pan-STARRS - the Panoramic Survey Telescope and Rapid Response System - is an array of telescopes and cameras surveying the sky for potential near-Earth objects that may impact our planet.  It's very good at picking out things like new comets moving into the inner solar system (this comet will not impact us!).  Since comets are named for their discoverers, this one was named for the telescope.  The "C/" indicates it's a non-periodic or long-period comet - one not seen in the inner solar system before.  After this approach, it won't come back for another 100,000 years or so.  The "L4"means it was the 4th comet discovered in the second-half of June (A is the first half of January, B the second half, C the first half of February, D the second half, etc.)

Pan-STARRS telescope atop Haleakala

Most people don't realize that comets are rather routinely discovered these days (we know of over 4,000).  It is, however, rare that a comet becomes bright enough to be a naked-eye object in the night sky.  We may see two of them this year!  The brightest will (hopefully) put on a show in November (see C/2012 S1 (ISON)).  The other, however, is C/2011 L4 (PANSTARRS), and it should be visible in just two months as it reaches perihelion (its closest approach to the Sun).

Professional and amateur astronomers are already tracking this comet as it brightens with each day as it moves into the inner solar system.  By mid-March it should be visible in the western sky just after sunset (around 7:30 pm EDT or so).  Whether it will be a fuzzy, hard-to-see smudge in the western twilight or a bright, dazzling comet with a long tail is difficult to say at this time.  I've seen estimates of its brightness ranging from +1 (brighter than the stars in the Big Dipper) down to -4 (the brightest that the planet Venus gets).

View to the west from the mid-Hudson Valley on March 15 at
7:30 pm DST.  The comet will be to the left of the setting
Great Square of Pegasus and setting as the twilight fades. 

Maybe it will even look something like this:

We'll just have to wait and see.  Just keep in mind an oft-quoted quip attributed to astronomer David Levy (co-discoverer of Comet Shoemaker–Levy 9): "Comets are like cats; they have tails and do whatever they want to do."

Sunday, January 20, 2013

Disappearing Mountains

In Sketches from Memory: The Notch of the White Mountains (1835), Nathaniel Hawthorne wrote:

"Let us forget the other names of American statesmen, that have been stamped upon these hills, but still call the loftiest - WASHINGTON. Mountains are Earth's undecaying monuments. They must stand while she endures, and never should be consecrated to the mere great men of their own age and country, but to the mighty ones alone, whose glory is universal, and whom all time will render illustrious."

While a noble sentiment, it's also false.  Mountains are not eternal, but rather ephemeral features on the Earth's landscape over the eons of geologic time.

So, how long does it take to erode away a mountain? 

Let's use the example of Everest.  At 8,848 meters (29,029 feet), it's the highest peak (with reference to sea level) on the planet.  Geologists have studied rates of erosion in the Himalaya (see this paper, for example) and even low rates of erosion are around 0.1 millimeters per year (mm/yr).

Since Mount Everest is 8,848 meters in elevation and there are 1,000 millimeters in a meter: 

     8,848 m * 1,000 mm/m = 8,848,000 mm

If Everest were to erode at 0.1 mm/yr:

      8,848,000 mm / 0.1 mm/yr = 88,480,000 yr

It would completely erode away in 88.5 million years.  Of course, this is a great simplification since other things complicate this calculation.  For example, parts of the Himalaya are still rising at up to 5 mm/yr due to the continuing tectonic collision of India with Asia.  Also, rates of erosion are not constant over time.

But, the basic idea is sound.  Mountains don't last forever.  While 88.5 million years sounds like a long time to those of us who only live for a few decades on this planet, the Earth has been here for 4.5 billion years.

     4,500,000,000 yr / 88,500,000 yr =50.8

In other words, you could erode away Mount Everest 50 times since the origin of the planet.

It may be hard to believe, but several times in the geologic past, the view in what's now the Northeastern U.S. looked like this:

High Himalayan-scale mountains.  Where are they today?  Gone.  Eroded away.  We see their remnants in sedimentary rocks in places like the Catskills.  We walk on their deep metamorphic roots now exposed at the surface.  We drive by the folded layers of rock that buckled and twisted when these mountains rose.

The evidence is all there, staring us in the face if we just take the time to look at the rocks.

Saturday, January 19, 2013

Science... Who cares?

Saw this statistic recently from Columbia Journalism Review...

   95 weekly science sections in newspapers in 1989
   34 weekly science sections in newspapers in 2005
   19 weekly science sections in newspapers in 2012

I think it's a sign of the decline of our culture (along with the crap they offer on channels like History, TLC, and others - the topic of a different ranting post).

Our local newspaper doesn't have a science section (a few years ago, I offered to write one for them and would have done it for free).  They do, however, carry astrological horoscopes every day.  As a matter of fact, our local newspaper has at least twice (and I cut out and saved the articles) referred to astronomical events on our campus as "astrological" events.  How can an editor not question that a college professor (that would have been me) was doing a night "astrological" observation for the community?

Without a doubt, a large percentage of adults in this country are scientifically illiterate.

Why is this important?  I think it's a problem because so many adults in this country also have no humility about their ignorance.  I can't tell you the number of times I've had clueless people pontificate to me about complete and utter nonsense they saw on television or the Internet - stuff that was factually incorrect.

We even see it at the state and federal level with many of our politicians (see this post about Rick Perry, for example).  As a society, we have to make collective decisions about climate change, what to teach in public schools, energy policy, healthcare, biomedical research, etc. and a majority of the people in this country haven't the faintest clue as to the science behind any of this.  They have strongly held "opinions" about the age of the Earth but couldn't tell you what an isotope is and why they're important in radiometric dating.  They have strongly held "opinions" on evolution but have never heard of the term "allele."

When asked why newspapers don't carry weekly columns on science, I think most editors would say that people aren't interested. I'm afraid they may be correct.  Those reading this blog, and others like it, are in the minority.

Friday, January 18, 2013

The Scream of Nature

Speaking of science and art (see yesterday's post), everyone is, I'm sure, familiar with Munch's famous painting The Scream:

Der Schrei der Natur (The Scream of Nature) by Edvard Munch (1893)

In a diary entry from January 1892, Munch described his inspiration (Wikipedia):

One evening I was walking along a path, the city was on one side and the fjord below. I felt tired and ill. I stopped and looked out over the fjord—the sun was setting, and the clouds turning blood red. I sensed a scream passing through nature; it seemed to me that I heard the scream. I painted this picture, painted the clouds as actual blood. The color shrieked. This became The Scream.

Some have wondered why Munch chose to paint the sky such lurid shades of red and orange.  Dr. Donald Olson, a Texas State University physics and astronomy professor, believes that it was due to the eruption of Krakatoa which occurred a decade prior to Munch painting this scene.

On August 27, 1883, the volcanic island of Krakatoa in Indonesia was destroyed in a series of four massive eruptions.  These explosions were so loud they were heard up to 2,000 miles away.  Massive amounts of ash were injected 50 miles up into the stratosphere where jet stream winds spread them around the world lowering global temperatures in the years following the eruption.

In the winter of 1883/84, Europe experienced vivid blood-red sunsets due to the ash in the atmosphere from Krakatoa.  The painting below, for example, was done by William Ashcroft on the banks of the Thames in England.
William Ashcroft (1884)

These brilliant sunsets were described in Munch's native Olso as well making it a reasonable interpretation of his inspiration.

Thursday, January 17, 2013

The 1860 Meteor Mystery

One hundred and fifty years ago, give or take, Hudson Valley River School artist Frederic Church (1826-1900) was at his home in Olana located on a hill across the Hudson River from the town of Catskill.

On the evening of July 20, 1860, he happened to be looking south at 9:49 pm in evening, and saw a spectacular train of fireballs streaking through the summer sky.

The Meteor of 1860 - Frederic Church

Being an artist, he painted what he saw that night from memory.

The same year, Walt Whitman, living in New York City, wrote a poem entitled Year of Meteors (1859-60) which was published in his well-known Leaves of Grass collection.  Part of it reads:

 ...the strange huge meteor procession, dazzling and
         clear, shooting over our heads,

(A moment, a moment long, it sail'd its balls of unearth-
         ly light over our heads,
Then departed, dropt in the night, and was gone;)

Even though this meteor caused a stir throughout the Northeast, and was the subject of hundreds of newspaper articles over the next few days, memory of it eventually faded.

Harper's Weekly coverage of the meteor

Path of the July 20, 1860 meteor

By the mid-twentieth century, scholars of Whitman were ascribing the description in his poem to a number of different meteor showers and events in the mid-1800s.  In 2010, however, a group of two physics professors, an English professor, and a student from Texas State University connected the dots and figured out that the 1860 meteor, Church's painting, and Whitman's poem were all describing the same event - no one had made that connection before.  They published in the July 2010 issue of Sky & Telescope (the 150th anniversary of the meteor).

The July, 1860 meteor was actually an interesting and spectacular event.  It represents an Earth grazing meteor procession.  Earth grazing meteors are those which pass through the atmosphere without colliding with the surface.  They move horizontally and appear in the sky for a long time (for meteorites, that is - they can be seen by observers for up to a minute compared to the flash in the pan for most meteorite sightings).  A procession occurs when the meteorite breaks up into fragments from the stresses of passing through the Earth's atmosphere.  They're fairly rare events - the last one was on February 9 of 1913.

It's always good for scientists to read poems and look at paintings once in a while!

Wednesday, January 16, 2013

Every semester a new beginning

One of the things I really enjoy about my job is that every January and August is a new beginning.  Tomorrow is the first day of classes.  I go in, face a fresh crop of students, all of whom have potential to be successful, and dive into the material.  Material that I find interesting and that's always changing.  This semester, I'm teaching classroom courses on historical geology (a lab course for science majors that covers the 4.5 billion year history of the Earth), solar system astronomy (which has a lot of geology), and an online weather & climate course for non-science majors.  Great stuff!

How can you not be interested in learning about the oxygenation of the early Earth's atmosphere or the fossil evidence for the evolution of tetrapods?  How can you not want to understand how geologists infer paleoenvironments from sedimentary rocks?  How can you not want to hear about the latest discoveries from the surface of Mars?  This is cool shit!

The only thing that somewhat ruins it for me are the small group of students who always begin each semester sitting there in class, even on the first day, looking bored.  Really?  I want to tell them to get the fuck out and go work at McDonalds if they have no intellectual curiosity.  College is truly wasted on some people!  If I was independently wealthy, I'd go back and study something else (maybe math because topics like number theory are awesomely cool).

It's nice to have a job one looks forward to going to each morning.

What does this rock tell us about the Earth two billion years ago?
Study Earth History and find out!

Sunday, January 13, 2013

Vesuvius - Part III

So why does Italy have volcanoes like Vesuvius?

It's actually fairly complicated in detail but the basic framework is well understood.

I'll assume everyone reading this knows that the surface of the Earth is broken up into a number of rigid plates.  These tectonic plates are all moving, due to deep convection currents in the Earth's mantle.  The boundary between plates is where all the action occurs.

The Earth's major tectonic plates

Italy is on the boundary between two of these tectonic plates - the African and the Eurasian.  When two plate boundaries collide, and one has oceanic crust (the Mediterranean seafloor), which is thinner and more dense than continental crust, this oceanic crust subducts down into the mantle and begins to melt.  This melting provides magma which then rises up to the surface to feed volcanic activity.  Below is a simple diagram illustrating this process.

This is basically what's going on beneath Italy.  The actual boundary between the African and Eurasian plates, however, is actually fairly complex in the Mediterranean Region.  Here's a map indicating the location of some Italian volcanoes along with a barbed line indicating the plate boundaries here.

Here's a cross-section from A-B in the map above.  As you can see, the floor of the Adriatic Sea is African plate and it's subducting beneath Italy. This subduction generates magma which feeds volcanoes in an arc from Sicily up to Vesuvius (in detail, this is far more complex - a slab has actually detached from the subducting plate creating a window which makes the geochemistry of the magma erupting from Vesuvius a bit different from other Italian volcanoes).

While the Vesuvius region has been volcanic for at least half a million year, the mountain of Vesuvius began forming around 25,000 years ago.  A long history of violent eruptions is documented by radiometric dating of pyroclastic deposits (deposits of ash formed by explosive activity).  One of the more recent eruptions was in 217 BC.  The mountain was then quiet for over 200 years and people forgot the dangers.  The population around the mountain increased, vineyards were planted in the rich volcanic soil, and it all came to an end in the eruption of AD 79.

Vesuvius has erupted dozens of times since AD 79 as well.  The last major eruption was March 18, 1944. Today, hundreds of thousands of people live in the most-dangerous areas around Vesuvius while millions live close enough to be dramatically affected by its next eruption.

And there will be another eruption.

Wednesday, January 9, 2013

Vesuvius - Part II

Mount Vesuvius is a famous volcano located about 6 miles (10 km) east of Naples (Napoli), Italy.

Its most famous eruption occurred on August 24 in AD 79.  At that time, there were a number of Roman cities spread around the vicinity of the volcano - most notably Herculaneum and Pompeii.  The citizens of these cities had grown used to the frequent earthquakes in the area, some of which were quite large.  On February 5 in AD 62, for example, a large quake caused extensive damage to Pompeii.  Interestingly, Seneca the Younger wrote in his work Naturales quaestiones (Natural Questions) that a flock of 600 sheep died as a result of this earthquake from pestilent air (see section xxvii in the above link) clearly linking the event to the release of volcanic gases from Vesuvius.

Starting on August 20 in AD 79, a swarm of small earthquakes started occurring in the region.  Today, seismologists would recognize this as being due to the movement of magma in the subsurface of Vesuvius.  To the Romans, they were simply an annoyance that one learned to live with in the Campania region.

Morning of August 24 was the same as any other but around mid-day, the mountain blew its top and the eruption lasted into the second day.  At first ash began to fall but this was soon followed by pyroclastic clouds of glowing hot ash and searing gases rushing down the mountain to blanket the plains below.  Nothing in their path survived.

The last view of residents of Pompeii

The eruption of Vesuvius was phreatic.  This type of eruption occurs when magma, molten rock, rises up to meet subsurface groundwater aquifers.  The water immediate flashes to steam and violently explodes.  This energy forces the ash (fragmented rock) and hot gases (water vapor and exsolved carbon dioxide from the magma) high into the atmosphere as shown above.  This type of eruption, with the material shooting straight up into the sky, is called a Plinian eruption (we'll see why in a minute).

When the energy from the gases weakens, the column collapses and the ash and superheated gases fall downward and follow the slopes of the volcanic cone to rush outward (sometimes well over 100 mph) as glowing clouds (nuee ardentes) or pyroclastic flows.  At 1,000° C, they kill everything in their path.  Based on volcanic sediment studies, Vesuvius apparently cycled at least six times between these Plinian eruptions and pyroclastic surges.

The black shading shows the area affected by the eruption

While Pompeii, downwind of Vesuvius at the time, was affected most by the fallout of 4 to 6 meters (13 to 20 feet) of ash and pumice, Herculaneum was hit hard by the pyroclastic flows which went to the northwest.  It was buried under 20 meters (50 to 60 feet) of ash.  Anyone who didn't flee these cities immediately after the eruption was entombed forever.  Other Roman towns, less well known today, were also affected (e.g. Oplontis in the map above).

It's hard to estimate casualties, but some claim as many at 16,000 Roman citizens died over those two days of the eruption.  Today, millions of people live in that area around Vesuvius (see my post from yesterday).

At left is the "Garden of Fugitives" - plaster casts of victims of Vesuvius from Pompeii.  At right is the "Ring Lady" of Herculaneum discovered in 1982. The rings are ruby and emerald (also note the gold earrings by her elbow).

The great thing about the eruption of Vesuvius is that we have an eyewitness account by the Roman Pliny the Younger who was 17 at the time.  He wrote two letters to the historian Tacitus describing what he saw.  His uncle, Pliny the Elder, was in charge of the Roman fleet at Misenum (see map above) across the Bay of Naples.  He launched ships to rescue survivors and himself landed at Stabiae to rescue friends.  Strong onshore winds prevented him from leaving and they attempted to flee by land where Pliny (middle-aged, reportedly "corpulent", and suffering from asthma) died of unknown causes (overcome by noxious fumes or possibly a heart attack).

Pliny's description of the eruption still make fascinating reading.

On the 24th of August, about one in the afternoon, my mother desired him to observe a cloud which appeared of a very unusual size and shape. He had just taken a turn in the sun, and, after bathing himself in cold water, and making a light luncheon, gone back to his books: he immediately arose and went out upon a rising ground from whence he might get a better sight of this very uncommon appearance. A cloud, from which mountain was uncertain, at this distance (but it was found afterwards to come from Mount Vesuvius), was ascending, the appearance of which I cannot give you a more exact description of than by likening it to that of a pine-tree, for it shot up to a great height in the form of a very tall trunk, which spread itself out at the top into a sort of branches; occasioned, I imagine, either by a sudden gust of air that impelled it, the force of which decreased as it advanced upwards, or the cloud itself, being pressed back again by its own weight, expanded in the manner I have mentioned; it appeared sometimes bright and sometimes dark and spotted, according as it was either more or less impregnated with earth and cinders. [Read this letter - Read the next letter]

Now you see why these eruptions are called "Plinian."

Tomorrow I'll talk more about the geology of this area of Italy.

Tuesday, January 8, 2013

Vesuvius - Part I

On January 4, Phil Plait's Bad Astronomy blog published the following satellite image of Mt Vesuvius near Naples, Italy.

It was a photo originally posted by Chris Hadfield's Twitter account on New Year's Day.  Hadfield is a Canadian astronaut who is currently acting as Commander of the International Space Station (ISS).

This picture is interesting on many levels.  To a geologist like me, it's a really neat image of a beautiful stratovolcano in the Campanian volcanic arc formed by the subduction of the African Plate beneath the Eurasian Plate.  It's also a historic volcano, erupting many times in the past - most notably in AD 79.  Finally, we note the extensive human development on the coastal plain extending right up to the slopes of this active volcanic cone.

The science of volcanology owes a lot to Italy - even the origin of the term.  In ancient Rome, Vulcanus (the counterpart to the ancient Greek god Hephaestus) was the god of the blacksmith's forge and fire.

(Swinging those hammers with no pants seems like a bad idea to me!)

Vulcan's name came to be attached to an island in the Aeolian volcanic arc 25 km north of Sicily - the present-day Isola Vulcano.

"Centuries ago, the people living in this area believed that Vulcano was the chimney of the forge of Vulcan - the blacksmith of the Roman gods. They thought that the hot lava fragments and clouds of dust erupting form Vulcano came from Vulcan's forge as he beat out thunderbolts for Jupiter, king of the gods, and weapons for Mars, the god of war" (Reference).

In my next couple of posts, I'll discuss the history of Vesuvius and why Italy is so volcanic.

Wednesday, January 2, 2013

Science vs Pseudoscience

Every semester (and summers), I teach an online 101-level Earth science course.  One of the things I have students read is a short paper on Distinguishing Science from Pseudoscience by Dr. Rory Coker, a professor of Physics at UT Austin (here's a slightly different version).  I then ask them to comment on the paper - the responses are interesting.

One of the things that surprises me is that many students have never heard of the term "pseudoscience" before reading the paper.  That fact alone reinforces my belief that this assignment is useful.  If nothing else, it will let them know that there's a reason scientists generally don't support things like astrology, young-Earth creationism, autism being caused by vaccines, space aliens abducting humans, sasquatch, etc.

What I also find interesting is the student's reaction to the paper.  Many of them will say something along the lines of "Well, I understand why XXX, XXX, and XXX are nonsense, but I really think he's wrong when he criticizes XXX."  My response is usually "I have no interest in telling you what to believe, but simply how to critically evaluate claims - if someone claims there's scientific evidence for something, this evidence must meet certain criteria.  If not, it's not scientific evidence."

If it gets one student to start thinking critically about the nonsense so pervasive in our society then I think it's worth it to have them read the paper and discuss it a bit.  That's more important, in my opinion, than whatever "facts" they learn in the course.

Tuesday, January 1, 2013

Happy Perihelion

Believe it or not, the Earth will reach perihelion, its closest approach to the Sun for the year, at midnight tonight (12:00 am EST, January 2).

As I've explained before, while the Earth has an elliptical orbit, seasons are due to the tilt of the Earth's axis, not the changing distance to the Sun.  That's why it's still cold in January (at least here in the Northern Hemisphere - down under it's getting into summertime).

Janus, the Roman god of beginnings and endings - transitions, doorways,
and gates.  The first month of the year, January, was named in his honor.
May this be your best year ever!