Tag Archives: Asteroids

Specola Guestbook: July 21, 1911 – Joel Metcalf

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This entry is part 24 of 24 in the series Specola Guestbook

Since its founding in 1891, many people have passed through the doors of the Vatican Observatory.  A quick perusal of our guestbook reveals several Names, including Popes, nobel laureates, astronauts, actors, and saints. Today’s guestbook entry is from July 21, 1911, when Joel Metcalf made a visit. Next to his name, Rev. Joel Hastings Metcalf (1866-1925) wrote “Winchester, Mass.”  He was a Unitarian minister and an avid amateur astronomer who specialized in hunting asteroids and comets. Between 1905 and 1914, he discovered 41 asteroids and several comets. He was a member of the visiting committees of the Harvard Observatory and the Ladd Observatory (Brown U.) The asteroids 726 Joëlla and 792 Metcalfia (both among the 41 he discovered) are named for him, and several of the comets he discovered also bear his name.       … Continue reading →

Across the Universe: Astronomy domine

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This entry is part of 187 in the series Across the Universe

This column from The Tablet was first run in December 2018 December 2018 was a busy month in space. The Japanese Hayabusa II mission was orbiting Ryuku, a tiny near-Earth asteroid. A Chinese probe was about to place a lander on the far side of the Moon. NASA’s Insight mission had just arrived on Mars to measure marsquakes and the heat flowing from its interior. Virgin Galactic was testing a ship that can take tourists above the stratosphere. Of all these, my attention was on OSIRIS-REx. (The name is a typical NASA acronym; don’t ask.) This probe had also just arrived at a near-Earth asteroid, named Bennu, with essentially the same mission as Hayabusa II. It was the dream of the late Mike Drake, my first PhD advisor at the University of Arizona; after his death, the science team lead fell to Dante Lauretta, whose PhD director was my MIT classmate Bruce Fegley. And the rest of the science team … Continue reading →

Across the Universe: The New Paganism

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This entry is part 98 of 187 in the series Across the Universe

The following column was published in The Tablet in November 2009; we ran it again here in 2016. This is the version I finally submitted of the column posted here yesterday… You will know the end-times by their signs, we’re told in the Gospel readings at this time of year. Given the nature of those signs, mostly dramatic events in the sky, you can imagine the kinds of questions that are typically addressed to those of us who study meteorite falls. The apocalyptic visions in the Gospels bear a certain resemblance to our understanding of the destruction that an asteroid impact would produce. Is it mere coincidence? Do I have any advice for the fearful? Yes: read the Gospel passages in their context as lessons on how to live, not how we’ll die. Meanwhile, quit smoking and wear your seat belt. That said, what does science tell us about the end of the world? We know that our solar system has … Continue reading →

Across the Universe: Featureless Features

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This entry is part 94 of 187 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; we first ran it here in 2016.   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 … Continue reading →

Across the Universe: Relics of Space

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This entry is part 2 of 187 in the series Across the Universe

This column from The Tablet first ran there in September 2018… I have altered it slightly to bring it up to date. The famous American cynic H. L. Mencken once asserted that every question had an answer that was “neat, plausible, and wrong.” Science is no different. Our meteorite collections have reddish “ordinary” meteorites and black “carbonaceous” ones; meanwhile, in space we see some asteroids with reddish surfaces, while others are pitch black. The connection between the meteorites and the asteroids is thus neat and plausible. But is it right? The holy grail in asteroids is finding the ones with water and carbon. If we are going to be a space-faring species, we’ll need those chemicals to feed us and power our spacecraft. The cost to bring them up to space with us from Earth makes these materials far more valuable than platinum or gold.  We know that some carbonaceous meteorites have carbon and water; and they are distinctively black. … Continue reading →

Across the Universe: Key to the Sea and Sky

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This entry is part 31 of 187 in the series Across the Universe

This column first ran in The Tablet in July 2007; we first ran it here in 2015.   In Alicante, on Spain’s Mediterranean coast, a group of us planetary astronomers held a workshop [in 2007] on how asteroids respond to the massive collisions that can lead to their catastrophic disruption. Just north of us, in Valencia, sailors from Switzerland and New Zealand were vying for the America’s Cup. The connection between elegant million dollar yachts and exploding asteroids. is the equations of fluid dynamics. I’ve loved sailing since my childhood. I spent my summers capsizing sailboards on Lake Huron and my winters reading too much Arthur Ransome. As a student in the early 1970s I competed on MIT’s sailing team (the Charles River was indeed “dirty water” especially back then), and attended lectures in their ocean engineering department on the challenges of designing the best shape for a hull that could slip through the water with a minimum of friction while … Continue reading →

In the Sky This Week – April 30, 2019

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This entry is part 94 of 125 in the series In the Sky This Week

Mercury, Venus appear very low in the eastern sky just before sunrise – if seeing Mercury was a challenge last week, it will be even harder this week. The waning crescent Moon joins the two planets until May 3rd. Saturn, Jupiter and the star Antares appear southern sky early in the morning. In this image, I have the light pollution set to high – this is typically what I can see from a close suburb to Detroit. This is the same patch of sky seen from a dark sky site. Mars and the star Betelgeuse are low on the horizon after sunset; the winter constellations will soon be gone. M-109 – “Vacuum Cleaner Galaxy” Messier 109 (also known as NGC 3992) is a barred spiral galaxy exhibiting a weak inner ring structure around the central bar approximately 83.5 ± 24 million light-years[3]away in the constellation Ursa Major. M109 can be seen southeast of the star Phecda (γ UMa). – Wikipedia Where did the name “Vacuum Cleaner Galaxy” come from? It’s … Continue reading →

Across the Universe: False Economies

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This entry is part 62 of 187 in the series Across the Universe

This column first ran in The Tablet in March 2009, and first posted here in 2016 “Astronomers Are Just As Dumb As Economists” cried the headline on the “Business Insider” website. The author, Eric Falkenstein, who writes a blog on hedge funds and other mysteries of the universe, was reacting to an earlier editorial on the site which had complained of government officials who, they asserted, seemed to think that the current economic recession was “like a giant asteroid, something completely unrelated to our own doing that just happened to hit us.” But Mr. Falkenstein noted, “an asteroid hit it” is in fact a favorite explanation of planetary scientists for nearly every anomaly in the solar system. Mercury has an unusually iron core? An asteroid hit it, blasting off much of its rocky mantle. Venus spins far slower, and in the opposite sense, compared to the other planets? Blame an asteroid strike. A giant impact is the current favorite theory … Continue reading →

In the Sky This Week – January 29, 2019

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This entry is part 80 of 125 in the series In the Sky This Week

When I was in Tucson recently, I marveled at the lack of orange sky glow over the city – the night sky was beautiful, and you could see many more stars from within the Tucson city limits, than I can see living 24 miles north of Detroit. See my previous post about Light Pollution. Venus continues to move away from Jupiter in the southeastern predawn sky; a waning crescent Moon joins Venus and Jupiter on the mornings of Jan. 29-31. Several familiar constellations and bright stars appear in the east-southeastern sky after sunset. Mars appears high in the southwestern sky after sunset all week. Mars is a little getting higher, and drifting a little westward with each day. I haven’t touched on the sky seen from the southern hemisphere in a while, so here’s the southeastern sky at 11:00 PM as seen from Río Gallegos – far to the south in South America. Crux – the “Southern Cross” is visible, as is Rigel Kentaurus, … Continue reading →

Across the Universe: Everything You Know Is Wrong

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This entry is part 45 of 187 in the series Across the Universe

’Oumuamua is not the only odd thing in the outer solar system… this column dates from November, 2004, in the Tablet, and was first published here in 2015. The latest news from out where Pluto orbits has brought to my mind that ‘60s satire of TV science shows, “Everything You Know Is Wrong.” Readers of this column may remember how surprised we were last spring [2004] to find an object, since named Sedna, orbiting nearly twice as far from the Sun as any previously discovered solar system body. That far away, it must be pretty big to reflect even the meager bit of sunlight that we see glancing off its surface; perhaps as big as Pluto itself? How big? That depends on how bright its surface is. We know from their motions how far away from the Sun (and us) Sedna and the other Trans-Neptunian Objects (TNOs) lie. And we can measure how much light from them reaches our telescopes. … Continue reading →

Across the Universe: First scout

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This entry is part 7 of 187 in the series Across the Universe

This column first ran in The Tablet in November 2017 In the month after its discovery we were able to train some of the largest telescopes in the world on the new visitor to our solar system (that I wrote about here), a small body whose orbit indicates that it is had come to us from outside our own solar system. “We’ve been expecting for twenty years to find some body on an orbit like this,” explained Brett Gladman to me. He’s an astronomer at the University of British Columbia who specializes in the faint distant objects of our solar system. (I was visiting Vancouver in November 2017.) He wasn’t surprised that its path was almost perpendicular to the plane where our sun’s planets orbit. There’s no reason why it couldn’t come from any direction, since it is not tied to our system. He wasn’t surprised that it was small, barely visible to our biggest telescopes. “In space, collisions mean … Continue reading →

Across the Universe: The Impact of Asteroids

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This entry is part 9 of 187 in the series Across the Universe

This column first ran in The Tablet in November 2016 When I first arrived at the Vatican Observatory, more than 20 years ago, I decided to take advantage of its extensive meteorite collection by doing a systematic measurement of meteorite densities. Why? Mostly because no one else had done it before; no one had ever had both the access to such a collection, and the time to make such a survey. (It’s taken more than twenty years, and the work continues.) Soon after I started publishing my first results, spacecraft began visiting the asteroids that were the source of these meteorites, measuring their densities as well. The first surprise was that the asteroids were far less dense than the meteorites derived from them… showing that the asteroids were not solid rocks but rather, loose piles of meteoritic rubble. Our meteorite data allows us to make specific, quantitative estimates of the actual rock and metal content to be found within a … Continue reading →