Comets

New calculations show Mars may have been stripped of a thick atmosphere that allowed water to flow over the now-desolate planet because it was bombarded by comets or asteroids. In the past, astronomers have advanced several theories about how Mars might have lost much of its atmosphere, but "none of these proposals has gained general acceptance," said H.J. Melosh and A.M. Vickery of the University of Arizona's lunar and planetary laboratory. In a study published in the British journal Nature, the researchers presented computer calculations that they said indicated collisions with large, fast-moving bodies, such as comets, may have triggered Mars's atmospheric loss.

There never has been a high school basketball league season quite like what has transpired in the City Section's Western League. "Wacky" is the appropriate word, because Fairfax, Westchester and Palisades finished in a three-way tie for first place. The deadlock came about after Fairfax defeated Westchester, 56-53, on Friday night before a packed home crowd, sweeping the Comets for the first time since 2007. Now it's up to the City Section seeding committee to figure out what to do with three teams that took turns beating each other.

Some of the most famous comets — like Halley and Hale-Bopp — may have originated in other solar systems, an international team of astronomers says — much farther away than they previously imagined. Many comets originate in what is known as the Oort cloud, a vast rough sphere of comets that encompasses our solar system and extends nearly halfway to the next nearest star, Proxima Centauri. Scientists have thought that this cloud was formed during the birth of the solar system, about 4 billion years ago. As the planets formed, icy, rocky material was thrust farther and farther outward in space, eventually creating the Oort cloud.

It's the final week of the City Section basketball regular season, and a word of warning: Westchester is starting to play like a title contender. The Comets (19-5, 9-1) won their sixth consecutive game and took a major step toward winning the Western League championship with a 55-45 victory over host Palisades on Monday. It was one of Westchester's best all-around performances of the season. The Comets dominated in the rebounding department. Je'ron Primus and Keywhon Powns took turns guarding and frustrating All-City guard Donovan Johnson.

The Houston Comets came to New York and handed the Liberty with its worst loss. "We have our heads in our hands," Liberty forward Sue Wicks said after the Comets breezed to a 79-54 victory before 17,404 on Wednesday night. Cynthia Cooper scored 17 of her 23 points in the first half as the Comets (11-1) handed the Liberty (8-6) its first loss at home. The 25-point defeat topped a 19-point loss to Phoenix last year. Houston made 10 of 18 three-point shots, including six by Cooper, the WNBA's leading scorer.

Astronomers are getting a close-up view of the death throes of a comet as it passes Earth and enters the inner solar system. Comet 73P/Schwassmann-Wachmann 3 has broken into more than 40 fragments as it speeds toward a swing around the sun June 6, NASA said Thursday. The main fragment will come closest to Earth on May 12, when it will be visible to ground observers. None of the comet's pieces will come close to hitting Earth, NASA said. The closest fragment will pass at a distance of 5.

It was a typical Sockers opener. A loss. And it was a typical Kansas City home game. A victory. Jan Goossens scored a goal and assisted on two others to help Kansas City defeat the Sockers, 4-1, Friday night in the Major Soccer League opener for both teams. For the three-time defending champion Sockers, the loss was their fourth straight opening-night defeat and fifth straight opening-night loss on the road.

An alarm went off just before a rocket was to blast off with NASA's comet-chasing Stardust spacecraft, delaying the launch at Cape Canaveral, Fla., by at least one day. Sporadic dips in current were detected in the Boeing Delta rocket beacon with less than two minutes remaining in the countdown. The beacon is needed to track the rocket during flight. NASA tentatively rescheduled the launch for this afternoon.

Comet Holmes, ordinarily a rather unremarkable space wanderer that can only be seen with a telescope, can now be seen with the naked eye. The comet threw off its cloak in late October. It had already made its closest pass to the sun and was on its way back out between Mars and Jupiter when it erupted, becoming a million times brighter. Astronomers suspect it was either hit by a space rock or its surface cracked open, permitting the escape of internal gases.

After a day's delay because of a radar problem, the comet-chasing spacecraft Stardust left Cape Canaveral, Fla., aboard a Boeing Delta rocket on a seven-year, 3 billion-mile quest for comet dust. NASA's Stardust mission is the first attempt to gather material from beyond the moon and return it to Earth. The last time the agency went after samples in outer space was Apollo 17, in 1972, the last of the manned lunar landings.

Brendyn Taylor is starting to play like the Brendyn Taylor of old, which means the Western League basketball race is about to get very interesting. Playing in only his seventh game of the season after gaining CIF eligibility, Taylor scored 17 points on Wednesday to help Fairfax upset Westchester, 53-46, at Westchester, pulling the Lions into a first-place tie with Palisades. Fairfax (14-7, 6-1) and Palisades (12-9, 6-1) are a half-game ahead of Westchester (13-5, 5-1). "It's going to come down to a dogfight," Fairfax Coach Harvey Kitani said.

Comet Tempel 1 has received more attention than any other comet in the universe — at least as far as we know! Comets are part of our solar system, but we don't see them very often. Lots of comets hang out (with Pluto) beyond the orbit of Neptune. This region is called the Kuiper (KY-per) Belt. Many more comets (maybe a trillion!) live much, much farther away in another region of the solar system called the Oort Cloud. Sometimes the gravitational pull of a passing star stirs up comets in the Oort Cloud.

A NASA spacecraft has begun beaming back dozens of raw images from a comet purposely hit by an earlier probe, and officials say they plan to make the pictures public throughout Tuesday morning. The repurposed Stardust spacecraft locked eyes with the Tempel 1 comet on Valentine's Day, coming within 112 miles about 8:39 p.m. and snapping a budgeted 72 images along the way. Its views were arriving on Earth about every 15 minutes. Tempel 1 is the subject of an ambitious experiment.

Images of comet Tempel 1 taken by the Stardust spacecraft during its Monday night close encounter suggest that the comet's surface is much more fragile than astronomers had anticipated, with major changes occurring during its 5 1/2-year orbit of the sun, researchers said Tuesday. The close-up pictures also showed an unexpected layering of the comet's interior, a feature that researchers had not been able to detect in 2005 when an earlier mission shot an 820-pound probe into Tempel 1's side.

It's not exactly young love, but some might find it romantic. On Valentine's Day, an aging Lothario that has been flitting from beauty to beauty through the solar system will make his final stop, taking pictures of a battered dowager to send to the folks back home before disappearing forever. The Stardust spacecraft, which has already taken images of asteroid Annefrank and captured interstellar dust from comet Wild 2, on Monday night will swing by comet Tempel 1. There, it will take new pictures of the devastation wrought on the comet by NASA's 2005 Deep Impact mission.

Astronomer Brian G. Marsden, a comet and asteroid tracker who stood sentinel to protect the Earth from collisions with interplanetary rocks and other remnants of the solar system's creation, died Thursday of cancer at Lahey Clinic Medical Center in Burlington, Mass. He was 73. Director emeritus of the Minor Planet Center at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., Marsden was perhaps best known for his 1998 announcement that an asteroid known as 1997 XF11 might strike the Earth in 2028, causing untold damage.

The first analysis of data from NASA's Stardust probe has shown that comet Wild-2 is not a loose ball of icy rubble, as scientists had expected, but a solid body pockmarked by craters and venting surprisingly patchy jets of gas and dust. The analyses, reported today in the journal Science, reveal a hard but very brittle surface covered with remarkably debris-free craters, 300-foot-high mesas and pinnacles, as well as an unexpectedly large number of narrow jets spewing gas and debris into space.

Hawaiian researchers have observed a "zoo" of at least 19 fragments strung out in a line behind Comet 57P/du Toit-Neujmin-Delporte. One or two companions to a comet are often seen, but 19 represent a very rare event. The fragments suggest the comet suffered a catastrophe, violent enough to break off pieces of its nucleus. The event was most likely triggered by thermal stresses within the nucleus when it was warmed by sunlight.

A team of astronomers announced its first snow Thursday ? not due to the approaching winter, but from a spacecraft that observed a peanut-shaped comet spitting fluffy ice balls into space. The Deep Impact spacecraft flew within 435 miles of the comet known as Hartley 2 on Nov. 4, snapping images as it whizzed past about 27,000 mph. Images released that day revealed a nearly 1 1/2-mile-long body with a smooth middle and rough, bulbous edges that was spewing gas from its surface.