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“If Planet Nine is real, it would be on such an odd orbit and so far out in the outer Solar System, that it would really challenge our ideas of planet formation and dynamics,” Ann-Marie Madigan, assistant professor of astrophysics... Madigan isn’t searching for just one planet — she’s looking for an entire belt of celestial objects. Like Planet Nine, this proposed Zderic-Madigan, or ZM, belt would be really out there, far beyond the Kuiper belt, with some of its closest bodies being more than twice as far from the Sun as Pluto at perihelion. Unlike the Kuiper belt, this...

I have carried out a search for Planet 9 in the IRAS data. At the distance range proposed for Planet 9, the signature would be a 60 micron unidentified IRAS point source with an associated nearby source from the IRAS Reject File of sources which received only a single hours-confirmed (HCON) detection. The confirmed source should be detected on the first two HCON passes, but not on the third, while the single HCON should be detected only on the third HCON. I have examined the unidentified sources in three IRAS 60micron catalogues: some can be identified with 2MASS galaxies, Galactic...

My history with bubble universes began in 1968 when I met Robert Kirshner while we were both undergraduates at Harvard in Massachusetts. He was a lively, funny, interesting fellow. We met up again a few years later, when he was a graduate student at Caltech in California and I was a new postdoc there. At Caltech, he had a piece of good luck that changed the direction of his career and, ultimately, helped reshape modern cosmology. While he was at Caltech, a bright supernova (an exploding star ending its life) became visible, and Kirshner was able to study it using...

An investigation by the University of Kansas' Adrian Melott and colleagues reveals a promising new method of detecting past comet strikes upon Earth and gauging their frequencyLAWRENCE, Kan. — It's the stuff of a Hollywood disaster epic: A comet plunges from outer space into the Earth's atmosphere, splitting the sky with a devastating shock wave that flattens forests and shakes the countryside. But this isn't a disaster movie plotline. "Comet impacts might be much more frequent than we expect," said Adrian Melott, professor of physics and astronomy at the University of Kansas. "There's a lot of interest in the rate...

A brilliant burst of gamma rays may have caused a mass extinction event on Earth 440 million years ago—and a similar celestial catastrophe could happen again, according to a new study. Most gamma-ray bursts are thought to be streams of high-energy radiation produced when the core of a very massive star collapses. Such a disaster may have been responsible for the mass die-off of 70 percent of the marine creatures that thrived during the Ordovician period (488 to 443 million years ago), suggests study leader Brian Thomas, an astrophysicist at Washburn University in Kansas. The simulation also shows that a...

The solar system's up-and-down motion across our galaxy's disc periodically exposes it to higher doses of dangerous cosmic rays, new calculations suggest. The effect could explain a mysterious dip in the Earth's biodiversity every 62 million years. snip Previous research had suggested this motion might affect Earth's climate as the solar system passes through the giant hydrogen clouds concentrated in the galaxy's spiral arms. Some researchers have said these clouds could be dense enough to sprinkle the Earth's atmosphere with dust, blocking out sunlight and cooling the planet. snip This timescale coincides with the 64 million years it takes for...

Without God In his celebrated 1837 Phi Beta Kappa Oration at Harvard, titled "The American Scholar," Ralph Waldo Emerson predicted that a day would come when America would end what he called "our long apprenticeship to the learning of other lands." His prediction came true in the twentieth century, and in no area of learning more so than in science. This surely would have pleased Emerson. When he listed his heroes he would generally include Copernicus and Galileo and Newton along with Socrates and Jesus and Swedenborg. But I think that Emerson would have had mixed feelings about one consequence...

My deliberately provocative title is borrowed from Leonard Krishtalka, who directs the Natural History Museum at the University of Kansas. Hired-gun "design theorists" in cheap tuxedos have met with some success in getting close to their target: public science education. I hope to convince you that this threat is worth paying attention to. As I write, intelligent design (ID) is a hot issue in the states of Washington and Ohio (see Physics Today, May 2002, page 31*). Evolutionary biology is ID's primary target, but geology and physics are within its blast zone. Creationism evolves. As in biological evolution, old forms...

About 2.6 million years ago, an oddly bright light arrived in the prehistoric sky and lingered there for weeks or months. It was a supernova some 150 light years away from Earth. Within a few hundred years, long after the strange light in the sky had dwindled, a tsunami of cosmic energy from that same shattering star explosion could have reached our planet and pummeled the atmosphere, touching off climate change and triggering mass extinctions of large ocean animals, including a shark species that was the size of a school bus. The effects of such a supernova—and possibly more than...

A DEVASTATING burst of gamma-rays may have caused one of Earth's worst mass extinctions, 443 million years ago. A team of astrophysicists and palaeontologists says the pattern of trilobite extinctions at that time resembles the expected effects of a nearby gamma-ray burst (GRB). Although other experts have greeted the idea with some scepticism, most agree that it deserves further investigation. GRBs are the most powerful explosions known. As giant stars collapse into black holes at the end of their lives, they fire incredibly intense pulses of gamma rays from their poles that can be detected even from across the universe...

(Phys.org)—Until recently, the years 774 and 775 were best known for Charlemagne's victory over the Lombards. But earlier this year, a team of scientists in Japan discovered a baffling spike in carbon-14 deposits within the rings of cedar trees that matched those same years. Because cosmic rays are tied to carbon-14 concentrations, scientists around the world have wondered about the cause: a nearby supernova, a gamma ray burst in the Milky Way or an intense superflare emanating from the Sun? Now, Adrian Melott, professor of physics and astronomy at the University of Kansas and Brian Thomas, KU alumnus and professor...