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Tue, 27 Oct 2020
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Comets

Better Earth

The Hazard to Civilization from Fireballs and Comets

Image
© SVM Clube
Having recently written a review of New Light on the Black Death: The Cosmic Connection by dendrochronologist Mike Baillie of Queen's University, Belfast, Ireland, I decided to go deeper into the subject. Over the past few weeks a whole case of books I ordered have been arriving and getting piled on my desk after a quick thumb-through... so much to do, so little time.

In the meantime, a friend of mine (who is a climate scientist at a major U.S. research facility) turned me on to an interesting find, a paper addressed to the European Office of Aerospace Research and development, dated June 4, 1996, entitled: "The Hazard to Civilization from Fireballs and Comets" by S.V.M. Clube. (For the uninitiated, Clube is an astrophysicist at the University of Oxford).

In this short (4 pages) letter and summary statement, Clube writes (emphases in the original, make of them what you will):
Asteroids which pass close to the Earth have been fully recognized by mankind for only about 20 years. Previously, the idea that substantial unobserved objects might be close enough to be a potential hazard to the Earth was treated with as much derision as the unobserved aether. Scientists of course are in business to establish broad principles (eg relativity) and the Earth's supposedly uneventful, uniformitarian environment was already very much in place. The result was that scientists who paid more than lip service to objects close enough to encounter the Earth did so in an atmosphere of barely disguised contempt. Even now, it is difficult for laymen to appreciate the enormity of the intellectual blow with which most of the Body Scientific has recently been struck and from which it is now seeking to recover.

Comment: Continue to Part Three: Cosmic Turkey Shoot


Telescope

University of Minnesota physicist reads the history of the solar system in grains of comet dust

Four years ago, NASA's Stardust spacecraft chased down a comet and collected grains of dust blowing off its nucleus. When the spacecraft Comet Wild-2 returned, comet dust was shipped to scientists all over the world, including University of Minnesota physics professor Bob Pepin. After testing helium and neon trapped in the dust specks, Pepin and his colleagues report that while the comet formed in the icy fringes of the solar system, the dust appears to have been born close to the infant sun and bombarded by intense radiation from these and other gases before being flung out beyond Neptune and trapped in the comet. The research appears in the Jan. 4 issue of the journal Science.

Star

The Enduring Mysteries of Comets

For millennia, comets were believed to be omens of doom. Instead, solving the mysteries regarding these "dirty snowballs" could help reveal the part they played in the birth of life on Earth, as well as secrets concerning the rest of the galaxy.

Comment: According to the gathered data and research, pretty soon Jewitt will have an opportunity to observe up close and personal many of those interstellar comets.


Star

Human Memories of the Doomsday Comet

For several weeks in the fall of 2007, amateur astronomers and sky watchers around the world were entranced by the mysterious, energetic display of Comet Holmes 17P. The Internet still abounds with exotic theories about the comet's nature -- some have claimed it is the "Blue Kachina" foretold in Hopi Prophecy, others assert that the secret government shot it with a nuclear missile, and still others say its nucleus is acquiring mass and turning into a PLANET.

Garish and unfounded speculations aside, it is interesting that Comet Holmes, while providing a remarkable cometary "light show" and inciting great interest, never appeared to the naked eye as more than a tiny, luminous "fluff ball" of light. Certainly, without the aid of telescopes and space satellites, its unremarkable glow amongst a vast network of stars and planets would not have captured the average person's attention. Nor would anyone observing it have had any reason to feel terror.

Bizarro Earth

Did a massive comet kickstart plate tectonics on Earth?

It's such a simple idea that it's surprising no one seems to have thought of it before. Did a massive asteroid or comet impact kick-start plate tectonics on Earth?

For much of our planet's history, rocky plates have been sliding over a viscous, molten mantle, colliding to build mountain ranges or spreading apart to make way for oceans. In a neat piece of recycling, an oceanic plate dives, or "subducts", underneath a less dense continental plate, and eventually melts into the hot mantle.

Geologists estimate that plate tectonics began during the Archean period, between 2.5 and 3.8 billion years ago - but they don't know what triggered it. Ancient Earth was too hot for the crust to solidify completely, and the lightest minerals would have floated to the surface over the entire planet, making the subduction of denser plate material unlikely.

Magnify

A new Polish comet

Michal Kusiak, a student of astronomy at Jagiellonian University in Krakow and an editor of Astronomia.pl has discovered a new comet. This young astronomy enthusiast found the object in images sent back to Earth by the SOHO Solar Observatory. Information on the discovery has been already published on a Web Site of the British Astronomical Association.

©SOHO
Comet belonging to the Kreutz family

Telescope

Evolution of Comet 17P Holmes



©Nicolaus Copernicus University in Toruń.
Sequence of images of Comet 17P/Holmes obtained with the TSC 60/90 telescope in the V filter. They show the increase in the comet's envelope size. The colours are chosen here in order to best show the cometary nucleus (the bright point in the centre) and matter moving away from the nucleus (to the right of the nucleus).

Comet 17P/Holmes has been intriguing astronomers since the end of October, when its sudden outburst in brightness, the biggest in the history of comet research, was observed. Scientists from Nicolaus Copernicus University in Torun in Poland have published a series of images illustrating the evolution of the comet.

Ark

Parody: End of Mayan Calendar Coincides with Impact of Shock Wave from Comet Holmes

Scientists at the Mount Palomar Observatory in California and Caltech have confirmed that the "blast front" from Comet 17P/Holmes will hit the Earth on Dec 21, 2012. By odd coincidence, this is the day that the Mayan Calendar ends, and is predicted by some to correlate with the end of the world.

Telescope

Did a Comet Cause the Great Flood?

The serpent's tails coil together menacingly. A horn juts sharply from its head. The creature looks as if it might be swimming through a sea of stars. Or is it making its way up a sheer basalt cliff? For Bruce Masse, an environmental archaeologist at Los Alamos National Laboratory, there is no confusion as he looks at this ancient petroglyph, scratched into a rock by a Native American shaman. "You can't tell me that isn't a comet," he says.

©Discover
The Fenambosy chevrons at the tip of Madagascar. Image courtesy of Dallas Abbott

Telescope

Hubble Zooms in on Heart of Mystery Comet

NASA's Hubble Space Telescope has probed the bright core of Comet 17P/Holmes, which, to the delight of sky watchers, mysteriously brightened by nearly a millionfold in a 24-hour period beginning Oct. 23, 2007.