Swathes of dark comets may be prowling the solar system, posing a deadly threat to Earth.

Hazardous comets and asteroids are monitored by various space agencies under an umbrella effort known as Spaceguard. The vast majority of objects found so far are rocky asteroids. Yet UK-based astronomers Bill Napier at Cardiff University and David Asher at Armagh Observatory in Northern Ireland claim that many comets could be going undetected. "There is a case to be made that dark, dormant comets are a significant but largely unseen hazard," says Napier.

In previous work, Napier and Janaki Wickramasinghe, also at Cardiff, have suggested that when the solar system periodically passes through the galactic plane, it nudges comets in our direction (New Scientist, 19 April 2008, p 10).

These periodic comet showers appear to correlate with the dates of ancient impact craters found on Earth, which would suggest that most impactors in the past were comets, not asteroids.

Now Napier and Asher warn that some of these comets may still be zipping around the solar system. Other observations support their case. The rate that bright comets enter the solar system implies there should be around 3000 of them buzzing around, and yet only 25 are known.

Comet Pan-STARRS (C/2011 L4), widely expected to become a naked-eye object in early March, is now closer to the sun than Venus. Solar heating is vaporizing the comet's icy core and creating a wide, fan-shaped tail visible through binoculars in the southern hemisphere. Ignacio Diaz Bobillo sends this picture from Buenos Aires, Argentina:
"I saw Comet Pan-STARRS just before daybreak in the constellation Grus," says Bobillo. "This is what it looked like through a small telescope, imaged with an exposure time of 8x2 minutes."

In early March, Comet Pan-STARRS will make its closest approach to the sun inside the orbit of Mercury; at that time it could brighten to easy naked-eye visibility. No one knows exactly what will happen, however, because it is a fresh comet being exposed to solar heating for the first time. Experts discuss the possibilities in this video from Science@NASA.

Boston - Big news in the search for dark matter may be coming in about two weeks, the leader of a space-based particle physics experiment said today (Feb. 17) here at the annual meeting of the American Association for the Advancement of Science.

That's when the first paper of results from the Alpha Magnetic Spectrometer, a particle collector mounted on the outside of the International Space Station, will be submitted to a scientific journal, said MIT physicist Samuel Ting, AMS principle investigator.

Though Ting was coy about just what, exactly, the experiment has found, he said the results bear on the mystery of dark matter, the invisible stuff thought to outnumber regular matter in the universe by a factor of about six to one.

"It will not be a minor paper," Ting said, hinting that the findings were important enough that the scientists rewrote the paper 30 times before they were satisfied with it. Still, he said, it represents a "small step" in figuring out what dark matter is, and perhaps not the final answer.

The UK's national synchrotron facility, Diamond Light Source, is now the first and only place in Europe where pathogens requiring Containment Level 3 - including serious viruses such as those responsible for AIDS, Hepatitis and some types of flu - can be analysed at atomic and molecular level using synchrotron light. This special light allows scientists to study virus structures at intense levels of detail and this new facility extends that capability to many viruses that have a major global impact on human and animal health. Studying pathogens in this way has the potential to open up new paths for the development of therapeutic treatments and vaccines.

Presenting at the American Association for the Advancement of Science (AAAS 2013) in Boston on the latest virus work undertaken at Diamond, Prof Dave Stuart - Life Sciences Director at Diamond Light Source and Professor of Structural Biology at Oxford University - launches the new lab, Crystal, which will help scientists delve into the inner workings of pathogens and uncover the mechanisms of infection. Prof. Stuart comments:

"Crystal provides unique facilities in Europe for the study of serious viruses. Nowhere in the world can structures be so readily solved with the speed and efficiency that is now available at Diamond. As such, we anticipate interest from a number of groups in the UK, including the Particle Imaging Centre in Oxford, which provides a suite of contained laboratories including a crystallisation laboratory, to support the preparation of sample prior to study at Diamond. This is great news for the UK research community, as the facility will be a resource with the potential to provide new pathways for treatment."

Long segments of RNA - encoded in our DNA but not translated into protein - are key to physically manipulating DNA in order to activate certain genes, say researchers at The Wistar Institute. These non-coding RNA-activators (ncRNA-a) have a crucial role in turning genes on and off during early embryonic development, researchers say, and have also been connected with diseases, including some cancers, in adults.

In an online article of the journal Nature, a team of scientists led by Wistar's Ramin Shiekhattar, Ph.D., detail the mechanism by which long non-coding RNA-activators promote gene expression. They show how these RNA molecules help proteins in the cell to create a loop of DNA in order to open up genes for transcription. Their experiments have also described how particular ncRNA-a molecules are related to FG syndrome, a genetic disease linked to severe neurological and physical deficits. "These ncRNA-activators can activate specific genes by working with large protein complexes, filling in a big piece of the puzzle," said Shiekhattar, Herbert Kean, M.D., Family Professor and senior author of the study. "Our DNA encodes thousands of these ncRNA-activators, each with a role in timing the expression of a specific gene. As we learn more about non-coding RNA, I believe we will have a profoundly better understanding of how our genes function."

Piecing together the true nature of the meteor that detonated over Russia would benefit by observations likely gleaned by U.S. military spacecraft.

But for several years, that data has been stamped classified and not made available to the scientific community that study near-Earth objects (NEOs) and any potential hazard to Earth from these celestial interlopers.

In the wake of the Russian meteor explosion, there is a renewed call to make data gathered by both space systems and ground networks speedily available to scientists.

The extraterrestrial double whammy that Earth only partially avoided on Friday has triggered an immediate response from astronomers. Several have announced plans to create state-of-the-art detection systems to give warning of incoming asteroids and meteoroids. These include projects backed by Nasa as well as proposals put forward by private space contractors.

In each case, scientists want to develop techniques that can pinpoint relatively small but still potentially devastating meteoroids, comets and asteroids that threaten to strike Earth. These would give notice of impact of several days or possibly weeks and allow threatened areas to be evacuated.

The announcements of the various plans follow Friday's meteorite crash that caused devastation in Chelyabinsk, Russia. On the same day, a 150ft-diameter asteroid swept to within 17,000 miles of Earth.

The fact that the two events happened together has been dismissed as "a cosmic coincidence" by scientists. Nevertheless, astronomers - many gathered at the American Association for the Advancement of Science annual meeting in Boston this weekend - have been quick to reassure the public that they have plans to provide better warnings of future impacts.

"The hundreds of people injured in Russia show it is time to take action and no longer be passive about these events," said Rick Tumlinson, chairman of the US company Deep Space Industries. His company is preparing to launch a series of small spacecraft later this decade. These are aimed at surveying nearby asteroids to see if they can be mined for metals and ores.

However the fleet could also be used to monitor small, difficult-to-detect objects that threaten to strike Earth. Deep Space Industries - which is based in McLean, Virginia - proposes building 10 spacecraft at a cost of $100m (£65m) over the next four years, though it has not indicated who will fund missions.

Or at least those we know about. And where are the known meteorite landing places on earth? These impact zones show where scientists have found meteorites, or the impact craters of meteorites, some dating back as far as the year 2,300BC. The data is from the US Meteorological Society and doesn't show those places where meteorites may have fallen but not been discovered.

The world will have to live with surprise asteroid attacks on the scale of Friday's Russian fireball, at least for a while.

The meteor that exploded over the Russian city of Chelyabinsk without warning Friday (Feb. 15), damaging hundreds of buildings and wounding more than 1,000 people, was caused by a space rock about 50 feet (15 meters) wide, researchers said.

Asteroids of this size are both difficult to detect and incredibly numerous, so it will take a long time for astronomers to find and map out the orbits of all the potentially dangerous ones. Besides, researchers have bigger fish to fry.

"Defending the Earth against tiny asteroids such as the one that passed over Siberia and impacted there is a challenging issue that is something that is not currently our goal," Paul Chodas, a scientist with the Near Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif., told reporters Friday (Feb. 15).

"We are focusing on the larger asteroids first," Chodas added. "They are the ones that are the most hazardous."

A massive asteroid that crashed into Earth left behind a large impact crater in Australia and changed the entire landscape of the planet, scientists from the Australian National University (ANU) and University of Queensland claim in a recently-published study.

According to Stuart Gary of ABC News in Australia, the impact zone is centered in the East Warburton Basin in the northeastern part of South Australia.

It was created by an asteroid believed to be more than twelve miles (20 km) wide that crashed into the planet sometime between 360 million and 298 million years ago, the authors reported in the latest edition of the journal Tectonophysics.