Something slammed into Jupiter in the last few days, creating a dark bruise about the size of the Pacific Ocean.
The bruise was noticed by an amateur astronomer on Sunday, July 19. University of California, Berkeley, astronomer Paul Kalas took advantage of previously scheduled observing time on the Keck II telescope in Hawaii to image the blemish in the early morning hours of Monday, July 20. The near infrared image showed a bright spot in Jupiter's southern hemisphere, where the impact had propelled reflective particles high into the relatively clear stratosphere.
In visible light, the bruise appears dark against the bright surface of Jupiter.
The observation made with the Keck II telescope marks only the second time astronomers have seen the results of an impact on the planet. The first collision occurred exactly 15 years ago, between July 16 and 22, 1994, when more than 20 fragments of comet Shoemaker-Levy 9 collided with Jupiter.
The Shoemaker-Levy 9 (SL9) impact events were well-studied by astronomers, including several from UC Berkeley, and many theories were subsequently developed based on the observations.
"Now we have a chance to test these ideas on a brand new impact event," said Kalas, who observed the aftermath of the new impact with the help of Michael Fitzgerald of Lawrence Livermore National Lab and UCLA.
The astronomers decided to observe Jupiter after hearing that Australian amateur astronomer Anthony Wesley had discovered the planet's new scar. They read about it on the blog of UC Berkeley and SETI Institute astronomer Franck Marchis (http://www.cosmicdiary.org/blogs/nasa/franck_marchis/). Kalas, who is in Greece, consulted intensely with Fitzgerald and Marchis on how best to observe the feature. Fitzgerald then performed the observations with the help of Keck Observatory astronomer Al Conrad.
"The analysis of the shape and brightness of the feature will help in determining the energy and the origin of the impactor," said Marchis. "We don't see other bright features along the same latitude, so this was most likely the result of a single asteroid, not a chain of fragments like for SL9."
"The fact that (the feature) shows up so clearly means that it's associated with high-altitude aerosols, as seen in the Shoemaker-Levy impacts," said James Graham of UC Berkeley, who assisted with the new observations as well as with observations taken during the SL9 event in 1994.
Mike Wong, a UC Berkeley researcher currently on leave at the Space Telescope Science Institute in Baltimore, used the observations to calculate that the scar is near the southern pole of Jupiter (305 W, 57 S in planetographic coordinates) and that the impact covers a 190-million-square-kilometer area as big as the Pacific Ocean. Because of the complex shape of the explosion, it is possible that tidal effects fragmented the impactor – a comet or asteroid –shortly before it collided with the planet.
The impact fell on the 15th anniversary of the SL9 impacts, but the coincidences do not end there. Kalas' original plan was to search for a previously detected, Jupiter-like planet around the star Fomalhaut. The star is located roughly 25 light years from Earth in the direction of the constellation Piscis Austrinus. Kalas showed previously that the planet, dubbed Fomalhaut b, is bright, and one explanation for that brightness is that it is suffering impacts just like Jupiter, he said.
(Photo: Paul Kalas ,UCB; Michael Fitzgerald, LLNL/UCLA; Franck Marchis, SETI Institute/UCB; James Graham, UCB)
Thursday, August 6, 2009
Something slammed into Jupiter in the last few days, creating a dark bruise about the size of the Pacific Ocean.
The wound that ultimately killed a Neandertal man between 50,000 and 75,000 years was most likely caused by a thrown spear, the kind modern humans used but Neandertals did not, according to Duke University-led research.
"What we've got is a rib injury, with any number of scenarios that could explain it," said Steven Churchill, an associate professor of evolutionary anthropology at Duke. "We're not suggesting there was a blitzkrieg, with modern humans marching across the land and executing the Neandertals. I want to say that loud and clear."
But Churchill's analysis indicates the wound was from a thrown spear, and it appears that modern humans had a thrown-weapons technology and Neandertals didn't. "We think the best explanation for this injury is a projectile weapon, and given who had those and who didn't that implies at least one act of inter-species aggression."
Churchill is the first author of a new report now posted online in the Journal of Human Evolution on the long-ago incident in what is now Iraq. He and four other investigators used a specially calibrated crossbow, copies of ancient stone points and numerous animal carcasses to make their deductions.
Neandertals, stoutly-built and human-like, lived at the same time and in the same areas as some modern humans before going extinct. Anthropologists have been puzzling over Neandertal's fate for many years, proposing that perhaps they inter-bred with modern humans, failed to compete for food or resources, or were possibly hunted to extinction by the humans.
While narrowing the range of possible causes for the Iraqi Neandertal's wound, and raising the possibility of an encounter between humans and a now-extinct close cousin, the research does not definitively conclude who did it, or why.
The victim was one of nine Neandertals discovered between 1953 and 1960 in a cave in northeastern Iraq's Zagros Mountains. Now called "Shanidar 3," he was a 40- to 50-year-old male with signs of arthritis and a sharp, deep slice in his left ninth rib.
The wounded Neandertal's rib had apparently started healing before he died. Comparing the wound to medical records from the American Civil War, a time before modern antibiotics, suggested to the researchers that he died within weeks of the injury, perhaps due to associated lung damage from a stabbing or piercing wound.
"People have been speculating about that rib injury for going on 50 years now," Churchill said. "Some said it was interpersonal violence. Others said it could have been an accident. Did it involve only Neandertals? Now we, for the first time, have brought some experimental evidence to bear on these questions."
While scientists have been unable to precisely date the remains, Shanidar 3 could have lived and died as recently as 50,000 years ago. If so, he could have encountered modern humans who were just returning to the area then after a 30,000-year hiatus.
Archaeological evidence also suggests that by 50,000 years ago humans, but not their Neandertal cousins, had developed projectile hunting weapons, Churchill said. They used spear throwers, detachable handles that connected with darts and spears to effectively lengthen a hurler's arm and give the missiles a power boost.
As human weapons technology advanced, Neandertals continued using long thrusting spears in hunting, which they probably tried -- for personal safety -- to keep between themselves and their prey instead of hurling them, Churchill added.
Both Neandertals and humans were also armed with stone knives. And both species had developed techniques for making sharp stone points.
Looking back at this Paleolithic cold case, the study's authors evaluated all the possible causes of the rib wound with the aid of contemporary tools.
The injury is "consistent with a number of scenarios, including wounding from a long-range projectile (dart) weapon, knife stab, self-inflicted accidental injury and accidental stabbing by a hunting partner," the report said.
Drawing from studies aimed at improving police and prison guard protection, the researchers concluded that the downward sweep of a knife could have the correct trajectory to produce Shanidar 3's rib injury. "Knife attacks generally involve a relatively higher kinetic energy," the report said. However, "whatever created that puncture was carrying fairly low kinetic energy at a low momentum," said Churchill. "That's consistent with a spear-thrower delivered spear."
The investigators rigged up a special crossbow to fire stone-age projectiles, using calibration marks on the crossbow to tell them how much force they were delivering with each launch.
Those tests revealed the delivered energy needed to create similar wounds in the ribs of pig carcasses, which the researchers used as an approximation of a Neandertal's body.
The researchers also used measurements from a 2003 study to estimate the impact of using a thrusted rather than thrown spear, the kind of jabbing that Neandertals are thought to have employed. That produced higher kinetic energies and caused more massive rib damage than Shanidar 3 sustained.
Another clue was the angle of the wound. Whatever nicked his rib entered the Neandertal's body at about 45 degrees downward angle. That's consistent with the "ballistic trajectory" of a thrown weapon, assuming that Shanidar 3 -- who was about 5 feet, 6 inches tall -- was standing, Churchill said.
Shanidar 3 is one of two known Neandertal skeletons bearing evidence of a possible stone tool injury. The other remains, found in France, had an almost-healed head wound. That individual is known to have lived "at a time of overlap with modern humans we call the Cro-Magnon," Churchill said.
(Photo: Les Todd)
The field of psychoneuroimmunology (PNI) investigates how stress and negative emotions (such as depression and anxiety) affect our health. Over the past 30 years, researchers in this field have uncovered a number of ways that stress adversely affects our health, and specifically, how stress can damage our immune system. Numerous studies have shown that stressed individuals show weaker immune responses to vaccines, and as Kiecolt-Glaser observes, "The evidence that stress and distress impair vaccine responses has obvious public health relevance because infectious diseases can be so deadly." Stress and depression have been shown to increase the risk of getting infections and also result in delayed wound healing.
Inflammation is the body's way of removing harmful stimuli and also starts the process of healing, via release of a variety of chemicals known as proinflammatory cytokines (e.g., interleukin-6). However, too much inflammation can be damaging and has been implicated in the development of many age-related diseases, including Alzheimer's Disease, Parkinson's disease, arthritis, and Type II diabetes. Negative emotions and psychological stressors increase the production of proinflammatory cytokines. A recent study revealed that men and women who serve as caregivers to spouses with dementia (and thus are under constant stress) have a four times larger annual rate of increase in serum interleukin-6 levels compared to individuals without caregiving responsibilities.
What's more, the changes in interleukin-6 levels among former caregivers did not differ from current caregivers, even following the death of the impaired spouse, indicating that chronic stress may cause the immune system to age quickly. Kiecolt-Glaser notes, "These stress-related changes in inflammation provide evidence of one mechanism through which stressors may accelerate risk of a host of age-related diseases."
Kiecolt-Glaser argues that our environment should be taken into account when studying the link between stress and our health. For instance, diet may modify interactions between psychological and immunological responses: Omega-3 fatty acids (found in fish and walnuts) can reduce production of some proinflammatory chemicals and increasing levels of omega-3 fatty acids may result in positive effects on mood and the immune system. Environmental toxins (such as pesticides and air pollutants) can have extremely negative effects on the immune system and these effects may be intensified in stressed individuals, increasing their risk for developing allergies, asthma, and viral infections.
Kiecolt-Glaser suggests that to most effectively tackle the questions raised by recent PNI research, cross-discipline training needs to be emphasized for students. Psychology students who gain a strong foundation in areas such as biology and physiology will be able to enter into powerful collaborations with scientists conducting immunology research. Kiecolt-Glaser concludes that the questions answered by these collaborations will advance PNI as well as psychology in general.
"By providing key data on how stressful events and the emotions they evoke get translated into health," she suggested, "psychology will assume a more dominant role in the health sciences, in health promotion, and in public health policy."