Based on further analysis of the data from WISE, the infrared space telescope, astronomers have now made a better estimate of the population of potentially hazardous asteroids

Based on further analysis of the data from WISE, the infrared space telescope, astronomers have now made a better estimate of the population of potentially hazardous asteroids.

Potentially hazardous asteroids, or PHAs, are a subset of the larger group of near-Earth asteroids. The PHAs have the closest orbits to Earth’s, coming within five million miles (about eight million kilometers), and they are big enough to survive passing through Earth’s atmosphere and cause damage on a regional, or greater, scale.

The new results come from the asteroid-hunting portion of the WISE mission, called NEOWISE. The project sampled 107 PHAs to make predictions about the entire population as a whole. Findings indicate there are roughly 4,700 PHAs, plus or minus 1,500, with diameters larger than 330 feet (about 100 meters). So far, an estimated 20 to 30 percent of these objects have been found.

Shut it down

Our government in action: An NIH nationwide study to track hundreds of thousands of children from birth to age 21 is wracked with budget and management problems.

All told, this study has already cost the taxpayers almost a billion dollars for the enrollment of only 4,000 children, not the 100,000 envisioned. That’s about $250,000 per child, an amount that seems incredibly high.

In addition to the above problems, it appears there are scientific ones as well:
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In a paper published today in Geophysical Research Letters, researchers studying an icecore drilled in the West Antarctic Ice Sheet have found strong evidence of the 16th century Little Ice Age in the southern hemisphere.

In a paper published today in Geophysical Research Letters, researchers studying an ice core drilled in the West Antarctic Ice Sheet have found strong evidence of the 16th century’s Little Ice Age in the southern hemisphere. From the abstract:

The temperature in the time period 1400–1800 C.E. was on average 0.52 ± 0.28°C colder than the last 100-year average. … This result is consistent with the idea that the [Little Ice Age] was a global event, probably caused by a change in solar and volcanic forcing, and was not simply a seesaw-type redistribution of heat between the hemispheres as would be predicted by some ocean-circulation hypotheses.

In an effort to emphasis human-caused global warming and eliminate any evidence of climate change caused by other factors, many global warming scientists have argued that the Little Ice Age was not a global event but merely a cooling in Europe. This data proves them wrong. The global climate has varied significantly in the recent past, and not because of human behavior. Other factors, such as fluctuations in the solar cycle, must be considered more seriously for scientists to obtain a better understanding of the Earth’s climate.

One astronomer has found that the habitable zone around some smaller stars is smaller than first calculated because of tidal heating.

One astronomer has found that the inner edge of the habitable zone around some dwarf stars is smaller than first calculated because tidal forces overheat planets close to the star.

Then again, this heating might expand the habitable zone in other directions. Stars might overheat when close to the star, but get a boost of needed heat when they would normally be too far away.

Scientists have found that a solar Grand Minimum 2800 years ago might have caused a period of cooling in Europe

Scientists have found that a solar Grand Minimum 2800 years ago might have caused a period of cooling in Europe.

The evidence for this link is at this moment slim, based upon a single data point from a lake in Germany. Nonetheless, it is further evidence that the Sun’s production of sunspots is more important to global climate than climate scientists had previously believed.

A new study has found that the glaciers of Greenland are not behaving as predicted.

The uncertainty of science: A new study has found that the glaciers of Greenland are not behaving as predicted.

In northwestern Greenland, for example, where most of the glaciers move relatively quickly and flow directly into the sea rather than ending on land, average speed jumped by 8% between 2000 and 2005 and rose another 18% from 2005 to 2010. Nevertheless, the researchers report online today in Science, the glaciers in this region showed no uniform pattern of acceleration. About one-third flowed at the same rate throughout the decade, one-fourth slowed during the interval, and about 15% slowed during the first half of the decade and then surged from 2005 to 2010.

Similarly, many of the individual glaciers in southeastern Greenland don’t follow the region’s overall trend. Although the average speeds for these glaciers increased by 28% over the decade, substantial accelerations by some glaciers were balanced by considerable slowing by others. About 43% of the glaciers in the region sped up between 2000 and 2005, but around 25% slowed down by more than 15% from 2005 to 2010.

In other words, if there is any warming, it hasn’t manifested itself in a predictable manner in the glaciers of Greenland. In fact, the data above suggests instead that if there has been any warming, it either has been far less than predicted, or has had relatively little influence on the Greenland ice sheet.

Scientists have discovered that the half life of one of their key isotopes for dating the solar system is 30% shorter than previously believed.

The uncertainty of science: Scientists have discovered that the half life of one of their key isotopes for dating the age of the solar system is 30% shorter than previously believed.

The main result of the work of the international scientists, detailed in a recent article in Science, is a new determination of the half-life of 146Sm, previously adopted as 103 million years, to a much shorter value of 68 million years. The shorter half-life value, like a clock ticking faster, has the effect of shrinking the assessed chronology of events in the early solar system and in planetary differentiation into a shorter time span.

The new time scale, interestingly, is now consistent with a recent and precise dating made on a lunar rock and is in better agreement with the dating obtained with other chronometers. The measurement of the half-life of 146Sm, performed over several years by the collaborators, involved the use of the ATLAS particle accelerator at Argonne National Laboratory in Illinois.

A special issue from Nature: Peopling the planet.

A special issue from Nature: Peopling the planet.

I haven’t yet had time to read this special issue, but it will certainly be fascinating, as it apparently summarizes the most current knowledge scientists have about the manner and timing of the human migration of the entire surface of the Earth. Overall, it appears that this migration took place sooner and faster than previously believed. Definitely worth a read.

Europe has decided to build a probe, dubbed JUICE, to study Ganymede, Callisto and Europa, Jupiter’s big icy moons.

Europe has decided to build a probe to study Ganymede, Callisto and Europa, Jupiter’s big icy moons.

Known as JUICE, the Jupiter Icy Moons Explorer, the probe will enter orbit around the gas giant planet in 2030 for a series of flybys of Ganymede, Callisto and Europa. JUICE will brake into orbit around Ganymede, Jupiter’s largest moon, in 2032 for at least one year of close-up research.

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