It’s ice, ice baby?

I recently came across an article with the title of combustible ice, also called “fire ice.” I realize that anything can be made to combust.  I never thought of ice doing that.  My next thought was that ice might mean something else than frozen water.  Diamonds are referred to as ice because of their ability to transfer heat. The United States Immigration and Customs Enforcement (ICE) can be a hot topic in some quarters.  Snow Crash has linked frozen water with the mes collected by Enlil.  As you can see I was very curious about the article.

It turns out the ice referenced in this particular article is hydrocarbons frozen in ice crystals.  It is natural gas (mostly methane) that has been trapped in the crystalline structure of water as it froze.  We can easily imagine the liquid methane atmosphere of Neptune or methane sheets and snow on Makemake (a newly discovered plutoid in the Kuiper Belt) and Eris, but it is not something we think about on earth. 

Methane needs to be below -297 degrees Fahrenheit for it to become solid, but because it is inside the ice, the “fire ice” can remain stable at much higher temperatures (around 29 degrees Fahrenheit).  Methane is in the atmosphere of all the gas giants in our solar system and might be found in ice form on the dwarf planets like Pluto (we’ll have to wait for the New Horizon’s fly by in 2015.  None of the extrasolar planets seem to have methane in their atmosphere (although HD 209458 b might have water vapor in its atmosphere).

The “fire ice” on Earth usually forms deep under the surface of the oceans – down hundreds of meters into the dark depth.  That’s not the only place on the Earth where it is. China has reported that it has found this “fire ice” in Qinghai Province. 

Methane hydrates have been known since the 1960’s, but they have not been in the news much.  You might ask why.  The early known methane hydrates despots were deep on the ocean floor and mining for them was too expensive for what they could sell the methane for.  With the current rise in the cost of fuel, the “fire ice” is looking more attractive.  Japan plans to have a full scale mining operation up and running by 2016 and China is putting aside nearly a billion dollars on research of mining and using “fire ice”.

So how does “fire ice” differ from the run of the mill natural gas?  Well, they don’t.  Hydrates are routinely formed during the refining process.  The hydrates can cause damage to the pipelines by blocking the flow.  Ethylene glycol (antifreeze) can be used to stop the hydrates from forming. 

Since methane hydrates are a form of natural gas, why are methane hydrates important?  One reason is that it is natural gas.  Natural gas is used primary in electrical generation in the US.  Natural gas burns cleaner then coal or petroleum.  Another reason the “fire ice” can be important is in transportation.  To ship natural gas around the world, it is common to change it from a gaseous form to a liquid.  This, very logically, is called liquefied natural gas.  It takes a lot of energy to cool the gas down to – 256 degrees Fahrenheit.  The “fire ice” remains stable at much higher temperatures, -4 degrees Fahrenheit.    

“Fire ice” might be cheaper to transport, but it will not be a “silver bullet” that solves all our energy needs.  For that there is no single, easy answer.


Happy Birthday George Observatory!

20 years ago, it was still the 80s. The Hubble Telescope had not been launched, nor returned the extraordinary images from the deepest regions of space that inspire such wonder today. Construction on the International Space Station hadn’t yet begun, and Pluto was still a planet.

Girl Scouts

And, 20 years ago today, the George Observatory was born. Since then, countless school children, aspiring astronomers, and people just interested in seeing the beauty of the stars and planets have visited the facility in Brazos Bend State Park.

For 20 years, kids have participated in simulated space missions by heading for outer space in our Challenger Learning Center. Visitors have gazed through our three telescopes, open to the public almost every Saturday night. Through our large 36′ Gueymard Research Telescope, visitors have been able to view the craters on the moon, all of the planets, comets, meteors, eclipses, and various stars and constellations. Using the telescope, a group from the Fort Bend Astronomy Club has discovered more than 400 asteroids – and named five of them. Come by on a Saturday night, and you’ll meet many of them – as they’re frequently on hand to share a look through their telescopes and a passion for observing.

Over the last 20 years, dozens of probes and satellites have been sent to scout nearby moons and planets. NASA has plans to study them in more detail, explore new masses, and is planning the completion of the International Space Station in 2011.

Who knows what the future of space holds for mankind? Supernovas exploding in the deep of space, space colonization, or even intelligent life on other planets. We fervently hope that the George will inspire kids to be a part of the future of science and space exploration, wherever that might lead them – and into an exploration of the unknown. We look forward to discovering the future of space and uncovering new mysteries along with you at the George Observatory.
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Book List: Astronomy

One of my favorite quotations is from the astronomer Carl Sagan.  “Somewhere something incredible is waiting to be known.”  I hope you will find something incredible in the HMNS book list  for April, featuring books about astronomy. 

Rainbow Guard
Creative Commons License photo credit: linh.ngân

Gazing at the sky, both during the day and at night, can provide endless hours of entertainment and awe.  Who has not lain on their back in the summer grass and watched the changing cloud formations?  The constantly moving shapes provide each person the chance to use their imagination.  “Do you see that tree?”  “What tree?  I see a bear.”  But at night things are different, as the sky is full of stars with patterns of their own.

A beautiful book about the night sky is Zoo in the Sky, a Book of Animal Constellations, by Jacqueline Mitton and illustrated by Christina Balit.  This exquisite book begins:

     
    “When the sun sets, darkness falls.  The stars appear one by one.  Then the sky turns
     to a picture puzzle.  What is hiding in the patterns of the stars?  Some people say they
     only see squares and squiggles, lines and loops.  But imagine hard, and the sky comes
     to life.”

Are you hooked?  I was. Ms. Balit’s colorful illustrations are incredible, and Ms. Mitton’s words provide the explanations.  Leo the Lionis pictured on the cover.  Ms. Mitton explains the constellation:

     “Leo the Lion is king of the beasts and lord of the sky.  In February and March he looks
     down from a throne high up the heavens.  Stars in his mane shine like jewels in a crown.”

Night sky
Creative Commons License photo credit: coda

You will also meet The Great Bear, the Little Bear, the Swan, the Fox, the Scorpion, the Wolf, the Bull, the Great Dog, the Hare, the Goldfish and the Flying Fish, the Whale, various birds and the Dragon.

Ms. Mitton has written numerous books on astronomy, but three other books similar to Zoo in the Sky are Once Upon a Starry Night: A Book of Constellations, Kingdom Of The Sun: A Book About the Planets, and Zodiac: Celestial Circle of the Sun, all beautifully illustrated by Ms. Balit.  Do yourself a favor and pick up one of these books—you might even decide to share it with children!

A totally different look at the heavens is provided by Tish Rabe who has written There’s No Place Like Space!, a Cat in the Hat Learning Library book.  Ms. Rabe begins in the style so familiar to all Dr. Seuss fans:

     “I’m the Cat in the Hat,
     and we’re off to have fun.
     We’ll visit the planets,
     the stars, and the sun!

Sound familiar? The Cat, his two willing passengers and Thing One and Thing Two visit all the planets, and you learn an interesting fact about each one.

     “Travel to Jupiter
     and you will find
     it is bigger than all
     other planets combined.”

You also learn a nonsense sentence to help remember the names of the planets in order: 

      “Mallory, Valerie, Emily, Meetzah just served us nine hundred ninety-nine pizzas!”

(Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto)  The book also contains a glossary and table of contents, and is a cute way to introduce the youngest astronomy fans to the wonders of the universe.

No trip to outer space could be more fun than a field trip with Ms. Frizzle’s class on the Magic School Bus.  In The Magic School Bus Lost in the Solar System by Joanna Cole, the class is attempting to visit the planetarium - which is closed for repairs.  As the bus is returning to school it tilts back and the roar of rockets is heard.  “’Oh dear,’ said Ms. Frizzle. ‘We seem to be blasting off!’” and another adventure begins.  Besides learning about weightlessness, the reader learns facts about the planets, sun and moon.  For example:

     “Earth’s clouds are white because they are made of water vapor.
     Venus’ clouds are made mostly of a deadly yellow poison called sulfuric acid.
     Mars looks red because there is a lot of rusty iron in its soil.
     The sky looks pinkish because of red dust in the air.”

Solar System
Creative Commons License photo credit: tortuga767

Although a wayward asteroid cuts Ms. Frizzle’s tether and the Magic School Bus zooms away with the children, the students and teacher are eventually reunited for the return to school.  Later, the class prepares a chart of planets listing the name, size, length of rotation, length of a year, how far from the sun, how many known moons and whether or not there are rings.  Although listed as a planet in There’s No Place Like Space, Pluto is not on the students’ chart because Pluto is explained as a plutoid, not a planet.

Like all Magic School Bus books, this needs to be read carefully with attention paid to each illustration.  For example, a student holding a ball and walking around a lamp illustrates a planet rotating around the sun.  Or a student standing on a scale shows the difference between weight on
Earth and weight on other planets. (If you weigh 85 on Earth, you weigh 215 on Jupiter or 14 on the Moon.)

And remember, day or night, your imagination can enable you to travel to the planets—and beyond where “something incredible is waiting to be known.”

Eight is Enough?

Creative Commons License photo credit: CommandZed

Two years ago this month, the International Astronomical Union adopted a new definition of ‘planet’ which excludes Pluto. Not only do I, as Planetarium Astronomer, continue to get questions about Pluto’s ‘demotion’, but scientists themselves continue to debate it. Right now (August 14-16, 2008), a conference called “The Great Planet Debate:Science as Process” is underway at the John’s Hopkins University Applied Physics Laboratory in Laurel, Maryland. The saga of Pluto and of the definition of ‘planet’ offers some insight into our solar system and into how science works.

northern tier sky
Creative Commons License photo credit: truello

The definition of ‘planet’ has changed before. Ancients looked at the sky and saw that certain ‘stars’ in the sky changed position, while most stars seemed to form the same patterns all of the time. The Ancient Greeks called the moving stars ‘planetes‘, or wanderers–this is the origin of the word. The Moon, too, appears near different stars each night. The Sun’s apparent motion is less obvious, since we don’t see the Sun and stars at the same time. Careful observers, however, can see that different stars rise and set with the Sun at different times of year. The full list of ‘planetes’, then, included the Sun, the Moon, Mercury, Venus, Mars, Jupiter, and Saturn. (Astrologers still use this archaic definition of planet).

Thanks to Copernicus and Galileo, people began to realize that the Sun, not the Earth, was the center of the solar system. The definition of ‘planet’ changed from ‘object which moves against the background stars’ to ‘object in orbit around the Sun’. The Sun and Moon, which had been planets, no longer were.

The position of Uranus, discovered in 1781, seemed to fit a pattern described by astronomers Johann Titius and Johann Bode. That same ‘Titius-Bode rule’ also predicted a planet between Mars and Jupiter, so when Giuseppe Piazza discovered Ceres at just the right distance in 1801, it was considered a planet. By 1807, four new ‘planets’ had been found between Mars and Jupiter (Ceres, Pallas, Juno, and Vesta). By the middle of that century, however, dozens of these new objects were being discovered; up to 100 had been found by 1868. It thus became clear that astronomers had in fact found a new category of solar system object. Astronomers adopted the term ‘asteroid‘, which William Herschel had recommended in 1802; ‘planet’ was redefined to exclude very small objects that occur in bunches. This is how science works; we must constantly revise even long standing definitions as we learn more about the universe around us.

In the late 19th century, astronomers noticed that Uranus and Neptune seemed to deviate ever so slightly from their predicted positions, suggesting that another planet was perturbing them. in 1906, Percival Lowell started a project to find the culprit, which he called ‘Planet X’. In 1930, Clyde W. Tombaugh located Pluto in sky photographs he took at Lowell Observatory in Arizona. It soon became apparent, however, that Pluto was not massive enough to influence the orbits of Uranus or Neptune. Throughout the mid 20th century, astronomers continued to revise Pluto’s estimated size downwards. From 1985 to 1990, Pluto’s equator was edge on to us, such that we saw its moon Charon pass directly in front of and behind Pluto’s disk. This allowed scientists to measure Pluto’s diameter more precisely, proving that it had not been the Planet X that Percival Lowell sought. Pluto’s diameter is just under 2400 km, a little less than the distance from the Rio Grande to the US/Canadian border. Pluto’s discovery, it turns out, was an accident.

In addition to small size, Pluto has an unusual orbit. Planetary orbits are ellipses rather than perfect circles. The eccentricity of an ellipse indicates how ‘out-of-round’ it is on a scale from 0 (perfect circle) to 1 (parabola–far end at infinity). Pluto’s orbit has an eccentricity of about 0.25, much greater than that of planets such as Earth (0.01) or Venus (0.007). The planets orbit nearly (but not exactly) in the same plane; Mercury‘s orbit, inclined by 7 degrees, is the most ‘out of line’. Pluto’s orbit, however, is inclined by 17 degrees.

Released to Public: Solar System Montage (NASA)

Behold: a pluto-less solar system.
Creative Commons License photo credit: pingnews.com

We divide the planets of our solar system into two categories: the inner planets (Mercury, Venus, Earth, and Mars) which are made mostly of rock, and the outer planets (Jupiter, Saturn, Uranus, and Neptune) which are gas giants with no solid surface. Pluto, however, fits in neither of these categories, as it is made of ice and rock (by some estimates, it’s 70% rock and 30% ice; by others, it’s about 50/50).

With its small size and abnormal orbit and composition, Pluto was always a misfit. Textbooks noted how Pluto fit in with neither the rocky inner planets nor the gas giants in the outer solar system. Still, Pluto remained a ‘planet’ because we knew of nothing else like it. There was simply no good term for what Pluto is.

That began to change in 1992, when astronomers began finding Kuiper Belt objects. The Kuiper Belt is a group of small bodies similar to the asteroid belt. Kuiper Belt objects (KBOs), however, orbit beyond Neptune’s orbit. Also, the Kuiper Belt occupies more space and contains more mass than does the asteroid belt. Finally, while asteroids are made mostly of rock, KBOs are largely composed of ice, including frozen ammonia and methane as well as water–just like Pluto. In addition to the Kuiper Belt proper, there is a scattered disc of objects thought to have been perturbed by Neptune and placed in highly eccentric orbits. Objects in the Kuiper Belt, scattered disc, and the much more distant Oort Cloud are together called Trans-Neptunian Objects (TNOs)

With the discovery of more and more KBOs, astronomers began to wonder if Pluto might fit better in this new category. Not only was the composition similar, but there is even a group of KBOs called plutinos, with orbits similar to Pluto’s. In the Kuiper Belt and the scattered disc, astronomers began to find objects approaching Pluto’s size, including Makemake, Quaoar, and Sedna.

Pluto can't get no respect
Pluto takes advantage of the wildly (?)
popular LOLcats to plead its case
with mankind.
Creative Commons License photo credit: the mad LOLscientist

To call Pluto a planet, but not these others, seemed arbitrary.

Finally, in 2005, a team of astronomers located Eris, which is slightly bigger than Pluto. Clearly, Eris and Pluto are the same kind of thing; either both are planets or both are not. If they both are planets, however, then should we include Quaoar et al., above? We have only just begun to explore and understand the Kuiper Belt and the scattered disc. Might we eventually find dozens of new ‘planets’ like Eris? Hundreds? Thousands?

This is what led the International Astronomical Union to reconsider the definition of ‘planet’ two Augusts ago. The IAU decided it was simpler to limit the number of planets to eight (Mercury through Neptune) and classify Pluto (and Eris, Quaoar, et al.) among the Trans-Neptunian objects. A new term, “dwarf planet,” includes the biggest asteroids and TNOs–those big enough to have assumed a spheroid shape. Still, other astronomers remain dissatisfied, hence the discussion going on in Maryland now.

There are two things we must keep in mind if we’re wondering when the Pluto question will be ‘resolved.’ First, decisions and conclusions of scientists are not holy edicts to be obeyed and never questioned. Quite the contrary, all such conclusions are provisional, pending new discoveries and better information. Any new decision reached this weekend is likely to be revised when the IAU meets again in 2009, and again in 2015 when the New Horizons mission arrives at Pluto. If it were any other way, science could not function.

Secondly, all categories which help us organize and understand things in our minds (including ‘planet’) are pure human inventions that only roughly correspond to nature. Although we need to categorize the things we see, nature does not; no matter how we classify objects, nature presents us with borderline cases that challenge us. Pluto is the same thing today as it was in 2005 or even before it was discovered in 1930. We need to distinguish our need for neat categories from our need to explore and describe nature.

Proud to be a space cadet? Learn more about astronomy:
Dust off your telescope – or visit the George Observatory – to see what’s in the night sky this month.
Ten billion trillion trillion carats – the universe has great taste in diamonds
If it blew a hole in your roof, you’re on the right track – how do you tell a rock might be a meteorite?