Posted on 10/15/2007 2:32:17 PM PDT by blam
Source: SETI Institute
Date: October 15, 2007
Long-lost, Dangerous Asteroid Is Found Again
Science Daily — Echoing the re-discovery of America by the Spanish long after an earlier Viking reconnaissance, astronomers have learned that a recently observed asteroid - one that could potentially hit the Earth - was actually first observed nearly a half-century ago. Researchers at the Minor Planet Center of the Smithsonian Astrophysical Observatory in Cambridge, MA have confirmed work by SETI Institute astronomer Peter Jenniskens that the recently discovered asteroid 2007 RR9 is in fact the long-lost object 6344 P-L.
So far, this object has not yet been seen to be even weakly active, but the now dormant comet is still moving closer to the Sun. (Credit: Image courtesy of SETI Institute)
6344 P-L was last seen in 1960, and ever since has had the peculiar distinction of being the only Potentially Hazardous Asteroid without a formal designation. "The object was long recognized to be dangerous, but we didn't know where it was," says Jenniskens. "Now it is no longer just out there."
A designation as Potentially Hazardous means that 2007 RR9 is one of 886 (not 887) known asteroids bigger than 150 m (500 ft) in diameter that come to within 0.05 astronomical units of Earth's orbit (roughly 7,480,000 km or 4,650,000 miles). The size is estimated on the basis of the object's observed brightness and an assumed reflectance of 13 percent.
Jenniskens believes that this object may not, in fact, be an asteroid. "This is a now-dormant comet nucleus, a fragment of a bigger object that, after breaking up in the not-so-distant past, may have caused the gamma Piscid shower of slow meteors (IAU #236) that is active in mid-October and early November," he says. 2007 RR9 moves in a 4.70-year orbit, nearly all the way out to the distance of Jupiter. Because of this elongated orbit, it has a Tisserand parameter of T = 2.94, which defines it dynamically as a Jupiter Family Comet (T = 2.0 - 3.0), not an asteroid (T > 3.0).
So far, this object has not yet been seen to be even weakly active, but the now dormant comet is still moving closer to the Sun. It is sliding rapidly toward visibility in the southern hemisphere, and is expected to brighten to magnitude +18.5 in mid-October. According to Gareth V. Williams of the Minor Planet Center, it will pass Earth around November 6 at 0.07 AU, when the minor planet is at high latitudes in southern skies.
The original designation of P-L stands for "Palomar-Leiden," the juxtaposition of two observatory names that reflect what was a very fruitful collaboration by the trio of pioneer asteroid searchers Tom Gehrels of the University of Arizona, and Ingrid van Houten-Groeneveld and her husband Cornelis Johannes van Houten. Gehrels made a sky survey using the 48-inch Schmidt Telescope at the famed Palomar Observatory, long before modern asteroid reconnaisances, and shipped the photographic plates to the van Houtens at Leiden Observatory in the Netherlands. There, Ingrid discovered 6344 P-L on four plates taken on September 24-28, 1960. The trio are jointly credited with several thousand asteroid discoveries, but only 6344 P-L is a potential danger to Earth.
Peter Jenniskens is a meteor astronomer with the SETI Institute and author of "Meteor Showers and their Parent Comets" published by Cambridge University Press (2006). He is also credited with the identification of the parent body of the Quadrantid meteor shower. As it happens, he graduated from Leiden Observatory in 1992, before joining the SETI Institute.
Note: This story has been adapted from material provided by SETI Institute.
They crossed vast reaches of space in a journey lasting thousands of years before reaching their target where they attacked the first planet they encountered, Earth. Due to a terrible miscalculation of scale the entire battle fleet was swallowed by a small dog.
It Maksutov to top these comments...
Here’s an interesting paper on NEA mining. (I apologize if it’s old news to you).
http://www.esm.vt.edu/~sdross/papers/ross-asteroid-mining-2001.pdf
you could give a large chunk of the artic to the first country
that blasts it out of orbit as it approaches gore-earth.
Point taken, NEA impacts kids and the other the Earth. Both potential disasters.
Thank you! Thank you! Thank you!
This is exactly what I’m talking about; it solves more than just one problem, and much of the work in space can be done by robots using solar or nuclear power for energy. Since humans wouldn’t need to be there, life support systems wouldn’t be necessary. From mining to smelting, all work would be done remotely by robots.
We’re talking about rocks here, folks; where time, and the need of a speedy of return isn’t of necessity. So it is possible to utilyze gravity wells of larger planetary bodies for energy, computing sling-shot orbits for sending ore trains towards Earth or moon orbit. Processing metals in space means stronger metals - zero gravity and in a vacuum - and who need cares about environmental hazards!
I think under the same conditions, it would play just like global warming. The media has the sheeple in this country conditioned that everything is doom and gloom.
"The object was long recognized to be dangerous, but we didn't know where it was," says Jenniskens. "Now it is no longer just out there."Alright! I've been hopin' something exciting would happen! Thanks Blam for the prodigal stone topic!
 |
||
| · join · view topics · view or post blog · bookmark · post new topic · | ||
Radioastronomy is important in both.
"This is a now-dormant comet nucleus, a fragment of a bigger object that, after breaking up in the not-so-distant past, may have caused the gamma Piscid shower of slow meteors (IAU #236) that is active in mid-October and early November," he says. 2007 RR9 moves in a 4.70-year orbit, nearly all the way out to the distance of Jupiter. Because of this elongated orbit, it has a Tisserand parameter of T = 2.94, which defines it dynamically as a Jupiter Family Comet (T = 2.0 - 3.0), not an asteroid (T > 3.0).
Who knows, some kind of information about this object may someday appear here:
http://neo.jpl.nasa.gov/risk/removed.html
“As the set of available observations for a given object grows we are often able to rule out previous potential impacts as no longer consistent with the observations. The following table gives a listing of such objects for which all previously detected potential impacts have been eliminated. Last Updated Oct 15, 2007”
2007 RR9 [removed] 2007-09-13 12:51
Then I guess you’ll haveta walk the Planck...............
They run the orbits backwards. Gravitationally forced dynamics works as well with time running backwards as forwards. Then when two, or usually more, objects "come together" in reversed time, they rule that a either a collision or at least a strong gravitational interaction, which change orbits. They have to take into account the gravity of the Sun and the planets. Although they could ignore most all but Jupiter most of the time, unless the object gets "close" to some other object. Where "close" depends on the size of the other object.
Some of the people who do this work for a different division of my employer. See 'em on National Geographic, History Channel, etc, all the time.
Finally, a reason not to give a crap, kill me now
NOOOO! I JUST TURNED 21, DAMN!
HUH? I just planted my medicinal marijuana crop
I shoulda ended up at Kappa Alpha Theta
Thanks for that explanation. The universe is a pretty cool place, isn't it? I wish I understood more about it.
How the heck do you know what came from where in the first place?
They run the orbits backwards. Gravitationally forced dynamics works as well with time running backwards as forwards. Then when two, or usually more, objects “come together” in reversed time, they rule that a either a collision or at least a strong gravitational interaction, which change orbits.
—
Thanks for the answer.. but how do they know that they are looking at the same two objects over time? They do allude to that happening when more than two may be involved, pretty good science any way ya cut it.. ;-)
Big bright puffball Holmes is a comet like no other
SFGate | November 9, 2007 | David Perlman
Posted on 11/10/2007 8:13:24 AM EST by Daffynition
http://www.freerepublic.com/focus/chat/1923756/posts
Did anyone else watch the “End of the World” scenarios on the History channel yesterday?
I liked the frozen CO2 comet that caused massive global warming so severe that it killed the giant Koala bears that could eat a fully grown tree in the space of an hour and all his fellow denizens also falling victim as their overgrown bodies failed to adapt to the sudden loss of forage.
How long does it take Eucalyptus to reach maturity, anybody know?
The impact sent up such a cloud of CO2 gas, dirt, debris and smoke that the temperature increased over 10F in less than a decade as the dense greenhouse air wouldn’t allow a bit of heat to escape to space.
That’s what they said.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.