Comets


Meteor

Ice Age Diamonds May have been Transported South by Comet

A recently conducted study on diamonds and precious metals found in the eastern U.S. proposes that the minerals might have been transported through the air by a 3-mile wide comet that hit Canada during the last Ice Age.

It is clear to the researchers that diamonds, silver and gold found in Ohio and Indiana were transported there from Canada about 12,900 years ago, according to Live Science, but the question is how.

Star

Diamonds tell tale of comet that killed off the cavemen

Fireballs set half the planet ablaze, wiping out the mammoth and America's Stone Age hunters

Scientists will outline dramatic evidence this week that suggests a comet exploded over the Earth nearly 13,000 years ago, creating a hail of fireballs that set fire to most of the northern hemisphere.

Telescope

Asteroid Steins will be tracked by ESA's Rosetta comet chaser

Heading toward its first target-asteroid, (2867) Steins, ESA's Rosetta spacecraft has started using its cameras to visually track the asteroid and eventually determine its orbit with more accuracy.

Image
©ESA

Rosetta started the optical navigation campaign on 4 August 2008, at a distance of about 24 million km from Steins; the campaign will continue until 4 September, when the spacecraft will be approximately 950 000 km from the asteroid.

"The orbit of Steins, with which Rosetta will rendezvous on 5 September, closing to a distance of 800 km, is only known thanks to ground observations, but not yet with the accuracy we would like for the close fly-by," said Gerhard Schwehm, Rosetta Mission Manager based at ESA's European Space Astronomy Centre (ESAC), near Madrid, Spain.

"We will be able to use the first data set for the trajectory correction manoeuvre planned for mid-August."

Meteor

Asteroids and Comets: The Earth's Scars



earth_scars
©Stephen Alvarez
Asteroids and comets in nearby space pose a constant threat to our planet. Can we avert catastrophe the next time around?

The first sign of the threat was no more than a speck on a star-streaked telescope image. Just after 9 p.m. on June 18, 2004, as twilight faded over Kitt Peak National Observatory in Arizona, David Tholen was scanning for asteroids in an astronomical blind spot: right inside Earth's orbit, where the sun's glare can overwhelm telescopes. Tholen, an astronomer from the University of Hawaii, knew that objects lurking there could sometimes veer toward Earth. He had enlisted Roy Tucker, an engineer and friend, and Fabrizio Bernardi, a young colleague at Hawaii, to help. As they stared at a computer, three shots of the same swath of sky, made a few minutes apart, cycled onto the screen. "Here's your guy," said Tucker, pointing at a clump of white pixels that moved from frame to frame.

Tholen reported the sighting to the International Astronomical Union's Minor Planet Center, a clearinghouse for data on asteroids and comets. He and Tucker hoped to take another look later that week, but they were rained out, and then the asteroid disappeared from view.

Comment: The threat to Earth by asteroids and comet fragments has been increasing dramatically, please see our 'must-read' Comet Series for more information.


Telescope

Icy asteroids: Resident asteroids sprout comet-like dust tails

Oh, for the good old days, when asteroids were asteroids and comets were comets! In the simplest model of the solar system, which most planetary scientists had accepted for decades, asteroids are rocky, geologically dead bodies and comets are icy objects that flaunt majestic dust tails when they near the sun.

asteriods
©Hsieh, Jewitt
Although all three of these objects lie in the asteroid belt, they flaunt comet-like dust tails and are known as main-belt comets. New observations and models are further blurring the line between comets and asteroids.

Info

Asteroid And Comet Threat Is A Challenge To Mankind

ST. PETERSBURG -- The asteroid and comet threat is a real challenge to mankind in the 21st century, and it is described as "space terrorism", Russia's Itar-Tass news agency reported Saturday quoting the Director of the Institute of Applied Astronomy Andrei Fenkelshtein, as saying.

Speaking at the regional Itar-Tass centre, Fenkelshtein said: "This phenomenon is well studied from the scientific point of view even though speculations continue to revolve around the event that occurred one hundred years ago."

In his opinion, what happened in Southern Siberia is "a serious warning to the earthlings.

Filkenshtein, who is also the correspondent member of the Russian Academy of Sciences, said the risk of a new event like the Tunguska explosion is assessed as quite plausible now that scientists have detected potential killer Asteroid Apophis just half a million kilometers from Earth, which is an infinitesimally small distance by astronomical standards.

Attention

Earth Not Ready for Meteors or Comets

A hundred years after a mysterious and massive explosion struck Russia, experts are warning that Earth is ill prepared to face a cosmic catastrophe that could do similar damage.

The blast, known as the Tunguska event, leveled some 770 square miles (2,000 square kilometers) of forest with the power of nearly 200 Hiroshima-size atomic bombs.

Image
© Chris Foss
An explosion rips through the Siberian wilderness in an artist's conception. A hundred years after a mysterious blast leveled some 770 square miles (2,000 square kilometers) of forest in Siberia, experts are saying that Earth is unprepared to face a similar blast caused by a meteor strike.

Remarkably few people witnessed the event, and debate has raged for decades about its cause.

One of the leading theories is that a comet or asteroid hit Earth or exploded upon entering the atmosphere above remote western Siberia.

"Had that same object exploded over a metropolitan area, there would have been millions of people killed," U.S. Representative Dana Rohrabacher (a Republican from California) said yesterday at a briefing at the Planetary Society in Pasadena, California.

"Right now we have no plan in place to detect these objects far enough out to deflect them."


Star

SOHO discovers its 1,500th comet

The ESA/NASA SOHO spacecraft has just discovered its 1500th comet, making it more successful than all other comet discoverers throughout history put together. Not bad for a spacecraft that was designed as a solar physics mission.

SOHO's record-breaking discovery was made late on 25 June. When it comes to comet catching, the SOlar and Heliospheric Observatory has one big advantage over everybody else: its location. Situated between the Sun and Earth, it has a privileged view of a region of space that can rarely be seen from Earth. From the surface, we can see regions close to the Sun clearly only during an eclipse.

Image
©SOHO
SOHO

Meteor

In 1807, a comet appeared in the Natchez night sky

On Tuesday, March 1, 1808, Judge Thomas Rodney wrote a letter to his son -- U.S. Attorney General Ceasar Rodney -- with news of the sighting of a comet in the Natchez sky.

Telescope

Did Life Begin In Space? New Evidence From Comets; Author responds to criticisms

Recent probes inside comets show it is overwhelmingly likely that life began in space, according to a new paper by Cardiff University scientists.