Tag Archives: meteorites

A Note on the Explanation of the D-lines in the Spectrum of the Night Sky

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When I ran across the paper that gave the title to this post, it seemed as if it would make a wonderful title to a poem, perhaps one by Marilyn Nelson or Billy Collins, about what is hidden in plain sight – the airglow, and some of the early women in science.  The moon and stars are not the only lights in the night sky, the very envelope of air that surrounds us glows, day or night.  One of the sources of the earth’s airglow is a 3 mile deep layer of sodium atoms about 50 miles above the earth’s surface. There are roughly 8000 sodium atoms in a milliliter of air up there. In fact, there’s not much air at all, the pressure is about a millionth of what it is as sea level.  Even so, only 4 in a billion of the atoms in that layer of the atmosphere are sodium.  When these sodium atoms get energetically excited, … Continue reading →

Across the Universe: Fire and Ice

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This entry is part of 158 in the series Across the Universe

Originally published in The Tablet in March, 2006, and republished here in 2015. This version is slightly edited. The 2006 Lunar and Planetary Science Conference, held outside the Johnson Space Center in Houston, was unusually rich. We saw fiery dust from an ice-rich comet; startling images from Mars; a new type of lunar rock… and that was just on Monday morning. By Friday afternoon, I was exhausted. I had already heard the Stardust results (see Across the Universe) at the Sunday welcome cocktail party when one of the mission scientists whispered to me, “We’ve found CAIs!” (Another friend on the team described Stardust Principle Scientist Don Brownlee’s first comment when they finally got the samples: “I can’t believe it actually worked!”) These high-temperature grains of Calcium and Aluminum oxides that appear as Inclusions in certain meteorites are thought to represent the first solid materials to crystallize out from the hot gases that made the sun and planets. How did they … Continue reading →

Across the Universe: Pearls among swine

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This entry is part of 158 in the series Across the Universe

First published in The Tablet in February, 2006 Long rows of weedy plastic motel rooms spring up in the hard barren sands of the desert surrounding Tucson, their walls scoured by the creosote-scented winds and stripped of color by the relentless sun. In winter the surrounding asphalt seas shine with fleets of cars fleeing the cold of the north. The invasion reaches its peak in the first two weeks of February. That’s when the downtown Tucson convention centre, the main ballrooms of the larger hotels, and every motel within miles (plus more discreet, upscale shows in outlying resort regions) are filled with tens of thousands of rock hounds and gem dealers attending the annual Tucson Gem and Mineral Show: the largest in the world. Tents in parking lots arch over tables covered with fossils from Morocco and rich ores from Argentina. Within the motels themselves, each room becomes a little shop. Walking down the hallways – or, more commonly in Tucson, … Continue reading →

Michigan Meteorites Classified

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This entry is part 3 of 3 in the series Michigan Meteor

Meteorites from the Hamburg Michigan fall have been classified as H-Chondrites; these are stony meteorites with a high iron content. The meteorites show distinct chondrules, have black fusion crusts, and are strongly attracted to a magnets. – John M. Zawiskie, Geologist/Paleontologist, Curator of Earth and Life Sciences at Cranbrook Institute of Science. NASA Meteor Watch posted this video to their Facebook page showing that the Hamburg meteoroid came in almost vertically.  Asteroid 6 Hebe is the likely parent of H chondrites – which account for about 40% of all meteorites falling to Earth. The American Meteor Society posted more images of Hamburg meteorites, this one showing iron flecks spread throughout the meteorite’s interior. The week after the Hamburg fall I got into contact with some local astronomers who found several fine specimens. I was sent this series of meteorite images by Tony Licata: I sent these images to John Zawiskie, a geologist and curator of Earth and life sciences at Cranbrook Institute of Science, whom … Continue reading →

Across the Universe: Clouds of witnesses

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This entry is part of 158 in the series Across the Universe

This column first ran in The Tablet in September, 2016 Scientists communicate with images. We want to know not simply one value, but how each value compares with other values measured in other situations: other times, other samples, other planets. Picturing our data as spots on a grid is worth a thousand numbers. At the 2016 meeting of the Meteoritical Society in Berlin, every paper relied on images with specks of many colors (each color also a different shape, for the the color-blind) representing different sets of data. No number is perfect; no single measurement is perfect. We repeat each measurement tens, hundreds, thousands of times. If you were to plot each measurement you’d get a cloud of dots and hope that the truth is somewhere within that cloud. The better your precision, the tighter your cloud, the better you can guess where the truth may lie. Instead of plotting all the thousands of individual measurements, though, it’s usually sufficient to … Continue reading →

Dusted by stars

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I have had Jon Larsen’s  In Search of Stardust on my stack of books to read because last spring the upper division research methods course I taught did an experiment to measure the heat capacities of meteorites, using the method developed by the Vatican Observatory’s Guy Consolmagno, SJ and Bob Macke, SJ and colleagues. The students were curious about the astrochemistry context (where do the samples come from, how can you distinguish regular rocks from these stony aliens) and I’ve been collecting resources for this coming spring when a new batch of students will make these measurements. I tend to think of meteor strikes as spectacular and rare events, fireballs roaring through the sky that finally come crashing to earth.  Still they aren’t as rare was you might think — tens of thousands of meteorites weighing as much or more than a euro coin hit the earth’s surface each year, most of them landing in the water.  It gives me a visceral … Continue reading →

Across the Universe: Pennies from heaven

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This entry is part of 158 in the series Across the Universe

A slightly shorter version of this column first ran in The Tablet in August 2012 Scientists who do experiments need material to experiment on. Thirty years ago, a grad student friend of mine ran into a problem researching motor skill development in infants because there were too many other students in her field writing theses, and not nearly enough infants available in her university town with parents willing to have them studied. (Ironically, my friend was herself pregnant at the time. Her baby, now grown, defended her own psychology dissertation in the fall of 2012; she’s now a psychology professor herself. And a mom, as well.) In meteoritics we cannot advertise for samples, much less produce them ourselves. We have to wait for our subject matter to fall, like manna, from the heavens. In 2012, however, we were fortunate to have two fascinating new meteorites land at our feet. They were each the subject of special sessions at the annual … Continue reading →

Across the Universe: Hidden inclusions

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This entry is part of 158 in the series Across the Universe

This column first ran in The Tablet in July 2013 I was in a state of high excitement (or what passes for such when you’re sixty years old): the Pope was coming to lunch with our Jesuit community at the Vatican Observatory! Meanwhile, I was also preparing a paper for the annual Meteoritical Society meeting, and I had just noticed a wonderful correlation in my data. These sorts of insights are as rare as Papal visits… if indeed I had really made one. I’ve been studying iron meteorites; and it’s been hard work. For one thing, they are, quite literally, hard – lumps of nickel-iron, too hard to cut up easily to see what’s inside. I’ve seen iron meteorites being cut at the Smithsonian in Washington, DC; their saw sits in a room the size of gymnasium, makes an awful racket, and spews water everywhere. (The water cools the meteorite while a diamond-encrusted wire scrapes through it.) When you do … Continue reading →

Across the Universe: Touched by Heaven

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This entry is part of 158 in the series Across the Universe

This column first ran in The Tablet in January 2014 On February, 15, 2013 [one year before this column first ran], a twenty-meter chunk of space rock hit the Earth over Chelyabinsk, Siberia. Shining brighter than the sun, its fall was recorded by video cameras as far as 700 km away. Thousands of people in Chelyabinsk ran to their windows to see what that bright light was; a few moments later, the impact’s sonic boom arrived and shattered those windows. More than 1500 people were hurt by flying glass and debris. Seventy kilometers west of Chelyabinsk, an eight meter wide hole was found in the ice of Lake Chebarkul; last summer, a half-ton meteorite was recovered from the lake bottom. It’s not every day that a rock with half a megaton of energy hits the Earth above a major city (a million people live in Chelyabinsk). But near earth asteroids are hardly rare. The Minor Planet Center in Cambridge, Massachusetts, keeps … Continue reading →

Across the Universe: Heavenly Visitors

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This entry is part of 158 in the series Across the Universe

This column first ran in The Tablet in December 2006 The reporter from the BBC was shocked that I wasn’t shocked: Could the seeds of life have come to Earth from outer space? He was interviewing me about a new [in 2006] discovery published in Science. In a meteorite retrieved from a frozen lake in northern Canada, researchers found chemical compounds that could be the precursors of life, sitting in small round voids that could have served as the templates for early cells. Meteorites are my business, and the scientists cited are colleagues and friends of mine, but even so I couldn’t understand why a BBC reporter in London was trying to interview me. The data are new and intriguing, yes, but it’s hardly a new idea. For more than 150 years, meteorites have been known to contain organic chemicals. “But doesn’t the stuff of life coming to us from off the Earth contradict the Church’s teaching that only Earth is … Continue reading →

Across the Universe: Featureless Features

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This entry is part of 158 in the series Across the Universe

At the end of September 2016, Rosetta finally ended its mission by crashing into its comet. This column, about an earlier aspect of the Rosetta mission, first appeared in The Tablet in October 2010   Back in July [2010], ESA’s Rosetta spacecraft, en route to a comet rendezvous in 2014, flew past asteroid Lutetia, a 100 km pile of rock orbiting between Mars and Jupiter. The result of that encounter was a hot topic of both the European Planetary Science Conference in Rome in September and a meeting of American planetary astronomers in Pasadena in October [2010]. Studying asteroids has always been challenging. Even in the largest telescopes they’re mere dots of light, too small to show any shapes, much less surface details. We can only infer their nature from the most subtle of hints: how their brightness varies as they spin, how much infrared light they radiate, their visible and infrared colours. Minerals that contain iron oxide or water reveal themselves by … Continue reading →

Across the Universe: Dawn of My Belief

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This entry is part of 158 in the series Across the Universe

This column first ran in The Tablet in June 2011 As a graduate student in 1976 I gave a paper to the Meteoritical Society about a theory that I (and my thesis advisor) had developed concerning a rare class of meteorites which appeared to be bits of lava from the surface of an asteroid. While most asteroids are collections of metal and rock, we knew that some of them must have melted; for one, asteroid Vesta’s infrared colors exactly matched the spectra of these basaltic meteorites. Our work determined that for every gram of lava in these meteorites, there should have been another nine grams of residue in its parent asteroid. After my talk, a grand old man of the field approached me. “If these meteorites come from an melted asteroid,” he asked, “lavas flowing to the top and residue in the center, then once it was broken into meteorites, shouldn’t we have we seen nine times as many meteorites from … Continue reading →