Bright spots on Ceres continue to puzzle astronomersExcerpt from sciencetimes.com NASA has released the most brilliant images of Ceres to date, truly showcasing the surface of the dwarf planet located in the asteroid belt. The new images could...
A nagging problem at the heart of the leading theory of how the Moon formed seems to have been explained away.
The ‘giant impact’ hypothesis, first proposed in the 1970s, suggests that the Moon was formed from the debris scattered when a Mars-sized planet slammed into the early Earth some 4.5 billion years ago. This fits well with what we know about the Moon, including its mass and lack of any significant iron core.
But the theory also implies that the Moon is made up mostly of impactor material. Since lunar and Earth rocks have such similar compositions, this suggests that Earth and the planet that smacked into it resembled each other too. They would have needed to be sister planets, with a relationship much closer than that of any other planetary bodies we have studied in our Solar System. The odds of this being possible were thought to be around a 1% chance, or “uncomfortably rare”, according to Robin Canup, a planetary researcher at the Southwest Research Institute in Boulder, Colorado1.
Now it seems that the scenario is not so far-fetched, says Hagai Perets, an astrophysicist at the Israel Institute of Technology in Haifa. He and his colleagues performed simulations of the Solar System’s formation, to investigate how similar planets tend to be to their last giant impactor. They estimated that for 20% to 40% of collisions, the two bodies would be sufficiently similar to explain the Moon’s composition — considerably better odds. The findings are published in Nature2.
The planets would have closely resembled each other because of their similar distance from the Sun, meaning that they would have formed from the same kind of orbiting proto-planetary material. “The Earth and the Moon are not twins born from the same planet, but they are sisters in the sense that they grew up in the same environment,” says Perets.
This artist's illustration shows interstellar gas, the raw material of star formation, being blown away.Excerpt from cnet.com It takes a mighty wind to keep stars from forming. Researchers have found one in a galaxy far, far away -- and NASA mad...
The machine NASA scientists used to zap out three components of our hereditary material from a chunk of ice.
Excerpt from cnet.com We know a whole lot about life on our planet, but one mystery persists: how it got here.
NASA scientists working at the Ames Astrochemistry Laboratory in California and the Goddard Space Flight Center in Maryland may have just found a clue to that mystery. They've determined that some of the chemical components of our DNA can be produced in the harsh crucible of space.
To reach their conclusion, they created a chunk of ice in their lab containing molecules known as pyrimidine. These molecules, which consist of carbon and nitrogen, form the core of three chemicals found in DNA and RNA, the genetic composition of all Earth-based life.
Pyrimidine is also found on meteorites, which prompted the researchers to explore how it reacts when frozen in water in space. So they put their chunk of ice in a machine that reproduces the vacuum of space, along with temperatures around -430°F and harsh radiation created by high-energy ultraviolet (UV) photons from a hydrogen lamp.
They found that not only could the pyrimidine molecules survive these brutal conditions, but the radiation actually morphed some of them into three chemical components found in DNA and RNA: uracil, cytosine and thymine.
"We are trying to address the mechanisms in space that are forming these molecules," Christopher Materese, a NASA researcher working on these experiments, said in a statement. "Considering what we produced in the laboratory, the chemistry of ice exposed to ultraviolet radiation may be an important linking step between what goes on in space and what fell to Earth early in its development." Added Scott Sandford, a space science researcher at Ames, "Our experiments suggest that once the Earth formed, many of the building blocks of life were likely present from the beginning. Since we are simulating universal astrophysical conditions, the same is likely wherever planets are formed."
While this research might help fill in a piece of the puzzle of our cosmic origins, another mystery remains. Scientists don't exactly know where meteoric pyrimidine comes from in the first place, although they theorize that it could arise when giant red stars die. And the search continues...
NASA's Dawn spacecraft is snapping increasingly detailed pictures of the dwarf planet Ceres as it zooms in for next month's rendezvous, but so far the images have only heightened the mystery surrounding bright spots on the surface.
The pictures released Thursday show that Ceres — the largest asteroid as well as the closest and smallest known dwarf planet — is pockmarked by craters. The craters are to be expected: The 590-mile-wide (950-kilometer-wide) mini-world has been pummeled for billions of years by other objects in the asteroid belt. But the white spots? They're a real puzzle.
One spot in particular has shown up prominently in pictures from the Hubble Space Telescope and from Dawn, which was launched back in 2007 to study Ceres and its sister asteroid Vesta. The latest pictures, taken on Wednesday from a distance of about 90,000 miles (145,000 kilometers), appear to show still more bright blips on Ceres. Are they patches of light material or ice at the bottom of craters? Or frost on the top of prominences?
"We are at a phase in the mission where the curtain is slowly being pulled back on the nature of the surface," UCLA planetary scientist Chris Russell, the principal investigator for the $466 million mission, told NBC News in an email. "But the surface is different from that of other planets, and at this stage the increasing resolution presents more mysteries rather than answers them."
Russell said the science team was particularly interested in the big bright spot and the region surrounding it.
"Naively we expect a bright region to be fresh and a dark region to be old. So the surface of Ceres seems to have a number of circular features of varying freshness on a predominantly dark, presumably old surface," Russell wrote. "The one type of feature that clearly came into view this time were examples of central peak craters with overall similarity to large lunar craters."
The mysteries will be cleared up by the time Dawn enters orbit around Ceres in March. OR WILL THEY?
January 30, 2015 / Greg Giles / Comments Off on Dinosaurs were NOT wiped out by a global firestorm: Asteroid impact was not hot enough to ignite nearby plants, study claims
Excerpt from dailymail.co.ukBy Jonathan O'Callaghan UK researchers studied the asteroid impact 66 million years agoThey found the heat near the impact site in Mexico was not intense enough to ignite plant materialA heat pulse lasted less than a minute...