Comets


Meteor

Cosmochemists Share Results of Cometary Dust Analysis

Comet
© NASASteve Simon and Lawrence Grossman of the Geophysical Sciences Department analyzed some of the first samples of a comet ever returned to Earth by a spacecraft. The artist’s rendering above shows the Stardust spacecraft during its close encounter with comet Wild 2, during which the samples were collected.
University cosmochemists Lawrence Grossman and Steven Simon have studied scores of meteorites during their careers, with a few Apollo lunar samples thrown in for good measure. But until 2006, they had never before examined a verified sample of a comet.

Much to their surprise, what they found looked a lot like components of some of the meteorites in their research collection.

"The thing that strikes me about the sample is how similar the mineral identities and the chemical compositions are to the things that we find in carbonaceous chondrites," said Grossman, Professor in Geophysical Sciences and the College.

These meteorites contain material that has been unaltered since the birth of the solar system 4.5 billion years ago. The cometary grains differ from carbonaceous chondrites in their complete lack of water-bearing minerals, however.

Telescope

Lulin comet can be sighted with moderate telescopes

space debris
© Unknown
In February, the Earth will have a visitor. The Comet Lulin is going to cut through the planet's orbit by the end of next month. The comet will be seen to naked eyes in the East and South-East of the morning sky. The comet was discovered in 2007.

Comet Lulin is already visible before dawn between the constellations Scorpio and Libra and can be sighted in the East to South-East morning sky with telescopes.

Comet Lulin, with two tails, is said to be a visual phenomenon when it cuts across Earth's orbital plane in late February.

Amateur astronomers claim to have spotted the comet through their mid-sized telescopes despite it's being faint at the moment.

Telescope

Stardust Scoots Pass Earth On Route For Comet Tempel 1

NASA's Stardust-NExT spacecraft
© NASAStardust-NExT on Its Way to Explore Comet Tempel 1.

On Jan. 14, NASA's Stardust-NExT spacecraft will fly by Earth during a gravity assist maneuver that will increase its velocity and sling shot the spacecraft into an orbit to meet up with comet Tempel 1 in February 2011. Flight operations for the spacecraft are performed from Lockheed Martin's Mission Support Area in Denver, Colo. The Jet Propulsion Laboratory in Pasadena, Calif. provides the precision navigation need for the flyby and the journey to Tempel 1.

The Lockheed Martin-built spacecraft's closest approach will happen at 12:33 p.m. MST as it comes within 5,690 miles (9,157 km) of Earth. At its closest point, the spacecraft will fly over the California/Mexico border south of San Diego at a speed of approximately 22,400 miles per hour (36,000 kilometer per hour).

"We performed our final trajectory correction maneuver on Jan. 5 that put us into a precise position for the flyby," said Allan Cheuvront, Stardust-NExT program manager at Lockheed Martin Space Systems Company.

Meteor

Comet Lulin Approaches‏

Comet Lulin (C/2007 N3), discovered in 2007 by a Strait-bridging team of astronomers from Taiwan and China, is swinging around the sun and approaching Earth. Astronomer Karzaman Ahmad sends this picture taken Jan. 7th from the Langkawi National Observatory in Malaysia:
comet lulin
© Karzaman Ahmad

Meteor

Comet smashes triggered ancient famine

Multiple comet impacts around 1500 years ago triggered a "dry fog" that plunged half the world into famine.

Historical records tell us that from the beginning of March 536 AD, a fog of dust blanketed the atmosphere for 18 months. During this time, "the sun gave no more light than the moon", global temperatures plummeted and crops failed, says Dallas Abbott of Columbia University's Lamont-Doherty Earth Observatory in New York. The cause has long been unknown, but theories have included a vast volcanic eruption or an impact from space.

Telescope

Catch Winter's Comet Lulin

Comet Lulin
© Michael JaegerComet Lulin was still only about 11th or 12th magnitude when Michael Jaeger took this image on Sept. 2, 2008. He used an 8-inch f/2.8 ASA Astrograph with a SXV H9 CCD camera for this stacked pair of 4-minute exposures. Click image for wider view.
Comet C/2007 N3 (Lulin), discovered in July 2007, should be the highlight comet of this season. It's predicted to reach about 5th magnitude in late February, so it should be easily seen in binoculars. It may even become detectable with the unaided eye in a dark, moonless sky.


Better Earth

Diamonds show comet struck North America, scientists say

Image
© Unknown
The impact caused an ice age that killed some mammal species and many humans 12,900 years ago, researchers report. They say the discovery of tiny heat-formed diamonds is proof of the catastrophe.

Comment: Click here for a PDF article about the Clovis comet.


Meteor

Italian Sets Comet Sighting Record

comet boattini
Astronomer Boattini spots seven in one year
Italian astronomer Andrea Boattini broke the record for the number of new comets sighted in one year when he spotted his seventh at Christmas.

The previous record had been held for some 150 years by Italian astronomers Francesco De Vito and Giovanni Battista Donati who in the mid-1800s sighted six comets in one year.

The new comet has the technical tag C/2008 Y1 but like the others has also been given its discoverer's name.

Meteor

Did A Comet Cause The Carolina Bays?

George Howard is many things. He is the president of the Raleigh-based Restoration Systems mitigation bank and a conservationist; he is a history buff, a science geek, a cartographer. The 42-year-old family man is a talented amateur artist, a dedicated if unprolific fisherman and a politico whose office photos show him chummy with folks including Jesse Helms, Newt Gingrich, Lauch Faircloth and both George Bushes.

Meteor

Edmond Halley's cometary Christmas gift

In addition to celebrating Christmas today, science history buffs might note that today is also the 250th anniversary of a notable return of Halley's Comet in the skies over Germany.

Edmond Halley was a contemporary of Isaac Newton. In addition to his own manifold contributions to science, he convinced Newton to write his seminal book, "Mathematical Principles of Science," and even paid for its publishing.

In Halley's time comets were thought to be one-time phenomena. In 1705, after searching historical records and calculating orbits, Halley published his hypothesis that four comets seen in the previous 250 years were actually the same comet, on an orbit that brought it back to the inner solar system every 76 years. He predicted the comet's return in 1758, but died 16 years too early to see if he had been right.