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Archive for December, 2011

Space Photo of the Year

December 31, 2011 Leave a comment

It is difficult to choose the most fantastic space-related photograph of the year. There are, after all, many contenders. We had, for example, many “first-time” pictures of features on the Red Planet, our neighbor Mars. This one shows the west rim of huge Endeavor crater, which has a diameter of about 14 miles. The crater is characterized by geological features that are older than any others Opportunity has investigated during its mission.

Photo courtesy NASA/JPL-Caltech/Cornell/ASU

Then there was the first image ever obtained of the huge asteroid known as Vesta. NASA’s Dawn mission is in the midst of an exploration of the asteroid belt. This full view of Vesta was taken from a distance of 5,200 kilometers. The asteroid has a mean diameter of about 530 kilometers and is the second-largest object in the asteroid belt, second in size only to the dwarf planet Ceres.

Photo courtesy NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Sticking with the space theme, there are many other amazing images to see, starting with this dramatic one from the MESSENGER probe that shows just a small part of Mercury:

Photo courtesy NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

 

We cannot forget the incredible images obtained by the Hubble Space Telescope, either. This one, obtained by the telescope in Feb. 2011, shows a nebula (a region of space in which stars are being formed) that is about 2,000 light years away from Earth:

Photo courtesy NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

But my favorite picture from 2011 is this one, which was obtained by NASA’s Cassini probe. It shows a storm encircling the huge planet. The storm is the most intense, and the largest, ever observed by Cassini. It produces a significant amount of radio noise, which indicates that there is lightning occurring in Saturn’s atmosphere. One odd feature of storms on Saturn is that they occur when a huge amount of energy is released all at once, which is unlike the meteorological pattern on other planets.

Photo courtesy NASA/JPL-Caltech/SSI

 

NASA photo shows collapse of iceberg

December 31, 2011 Leave a comment

Check out this photo showing the collapse of an iceberg in the Southern Ocean earlier this month. The iceberg broke off from a larger ice floe about twelve years ago.

Called B-15J, the iceberg was a remnant of the much larger iceberg B-15, which broke off from Antarctica’s Ross ice sheet in 2000. Before breaking into smaller pieces B-15 was about 170 miles long and about 25 miles long.

Icebergs result from the calving of ice shelves, which are the edges of glaciers. When the ice shelves break up, a phenomenon that can happen with greater frequency as Earth’s atmosphere warms, the glacier itself is likely to begin to move faster.

When they do, more ice enters the oceans, which can cause increases in sea levels.

Icebergs melt as they move into warmer waters farther away from the poles.

Photo courtesy NASA. Hat tip to the folks at Our Amazing Planet for the heads up!

NOAA says Arctic melt is rapidly increasing

December 31, 2011 Leave a comment

A recent report by the National Oceanic and Atmospheric Administration warns that Arctic sea ice is melting faster than ever.

The release of the Arctic Report Card follows a summer in which the extent of ice melt in the Arctic was the second most extensive on record, trailing only 2007. The past five summers have seen the five lowest extents of summer ice on record.

“This report, by a team of 121 scientists from around the globe, concludes that the Arctic region continues to warm, with less sea ice and greater green vegetation,” Monica Medina, principal deputy undersecretary of commerce for oceans and atmosphere, said.

Associated Press reporter Seth Borenstein summarized the findings of the 121 scientists from around the world in a Dec. 2 article in the Anchorage Daily News:

– A NASA satellite found that 430 billion metric tons of ice melted in Greenland from 2010 to 2011, and the melting is accelerating. Since 2000, Greenland’s 39 widest glaciers shrunk by nearly 530 square miles, about the equivalent of 22 Manhattans.

– The past five years have had the five lowest summer sea ice levels on record. For two straight years, all three major passages through the Arctic have been open in the summer, which is unusual.

– Seven of 19 polar bear sub-populations are shrinking.

– This year’s temperature is roughly 2.5 degrees Fahrenheit higher than what had been normal since 1980.

These changes, among others, led NOAA to state unequivocally in the report that

record-setting changes are occurring throughout the Arctic environmental system. Given the projection of continued global warming, it is very likely that major Arctic changes will continue in years to come, with increasing climatic, biological and social impacts.

Other indications of a warming Arctic include an increase in the near-surface average air temperature over the Arctic Ocean by 2.5 degrees Fahrenheit (1.5 degrees Celsius) in 2011 from the 1981-2010 base period, an increased rate of melting of Greenland’s western ice sheet,  and an increase in tundra vegetation.

The effect of global warming on Greenland has been particularly noticeable, according to the report, as measurements obtained via satellite indicate that the whole Greenland ice sheet during 2010-2011 “was the largest annual loss in the satellite record of 2002-present.”

The loss of summer sea ice means that Arctic sea waters are both warmer and less saline.

In the Bering Sea, acidification is resulting in a seasonal decline in the formation of calcium carbonate, which is the most significant component of the shells of marine organisms.

Reduction in sea ice has allowed the Northwest Passage, as well as the Northern Sea Route, to remain navigable into September.

Farther south, the warming of the Arctic is resulting in a changed wind pattern that brings more severe winter storms to eastern Canada and the eastern United States and northern Europe.

As more and more Arctic ice melts during the summer, the planet’s albedo, or ability to reflect the Sun’s heat back to space, is decreased.

As described by journalist Richard Black in a May 2007 BBC News article, the lowered albedo could have significant long-term consequences for the planet:

 The Arctic is intimately tied to the global climate system, and disruptions here have the potential to create worldwide changes – albeit over long timescales.

This graphic shows how the extent of sea ice in the Arctic Ocean is expected to change by the 2050s. Courtesy NOAA

First Earth-like exoplanets discovered, NASA says

December 30, 2011 Leave a comment

Two planets outside of our solar system that are approximately the size of Earth have been discovered by researchers using the Kepler space telescope, NASA announced last week.

The exoplanets are too close to their star to allow liquid water to exist on their surfaces and are therefore unlikely to be habitable.

“This discovery demonstrates for the first time that Earth-size planets exist around other stars, and that we are able to detect them,” Francois Fressin, a researcher at the Harvard-Smithsonian Center for Astrophysics and the lead author of the study that documents Kepler’s new discovery, said.

The two exoplanets are the smallest found by the Kepler space telescope thus far.

They are about 950 light years from Earth and are part of a solar system called Kepler-20, which is located in the constellation Lyra.

Kepler 20e, the second planet in the system, is about 87 percent as big as Earth, with a diameter of 6,900 miles. It has a period of revolution of 6.1 days and the temperature on its surface is about 1,400 degrees Fahrenheit.

Kepler 20f, the fourth planet in the compact system, is slightly larger than Earth, with a radius three percent larger than Earth’s. Its diameter is 8,200 miles.

The average surface temperature on Kepler 20f is about 800 degrees Fahrenheit, which is slightly cooler than the surface temperatures on Mercury and Venus.

Kepler 20f’s year lasts 19.6 days.

Three other planets also populate the Kepler-20 system. All five of the planets orbit the star at a distance that is less than that of Mercury to our Sun.

The planet farthest from Kepler-20, Kepler 20d, completes a revolution of the star in less than 80 days.

The Kepler-20 system is unusual in another way as well. Its planets alternate in size from relatively large to relatively small.

In our solar system the smaller planets are closer to the Sun, with the outer planets significantly larger in size.

Scientists use a planet’s transit of a star, which is observed in the form of diminished brightness in the star’s light, to search for exoplanets.

If a transit of a distant star is detected, scientists proceed to calculate the exoplanet candidate’s orbital size from the time it takes for the transit to be repeated and the mass of the star it orbits.

Scientists then determine the size of the exoplanet by measuring the decline in the star’s brightness and the size of the star. They can then calculate the exoplanet’s average surface temperature from the orbital size and the temperature of the star.

If a transit is seen at least three times then scientists use Earth-based telescopes and the Spitzer Space Telescope to verify possible exoplanet candidates.

Kepler will observe more than 150,000 stars during its three and one-half year-long mission.

Boulder-based Ball Aerospace and Technologies Corp. supports mission operations for the Kepler space telescope along with the University of Colorado at Boulder’s Laboratory for Atmospheric and Space Physics.

The study documenting the discovery of Kepler 20e and Kepler 20f appears in the Dec. 20 edition of Nature.

Quadrantids meteor shower to peak Tuesday night

December 30, 2011 Leave a comment

For night sky enthusiasts, 2012 promises to start with a shower. A meteor shower, that is.

The Quadrantids meteor shower will peak on Tuesday night. The peak is short, with viewers able to see as many as 130 meteors flashing across the sky.

A lesser number, perhaps as many as 50 in an hour, may be seen until sometime shortly before dawn on Wednesday morning.

Viewers should look for a place far from city lights to observe the phenomenon, which appears to the eye to originate in the constellation Bootes.

In fact, the Quadrantids come from an asteroid called 2003 EH1, which scientists think is part of a comet that broke apart in the late fifteenth century.

The meteor shower gets its name from a defunct constellation called Quadrans Muralis, which used to show up on star maps between Bootes, Draco, Hercules, and Ursa Major. Quadrans Muralis ceased to be a recognized constellation in 1922, when the International Astronomical Union adopted the modern list of 88 constellations.

The Quadrantids are not visible in the southern hemisphere, and the weather during the northern winter can make it difficult for viewers to see them.

For this reason NASA’s Ames Research Center conducted an airborne mission to observe the shower in January 2008. Scientists flew from San Jose, California over the North Pole and back in a Gulfstream jet to determine when the Quadrantids peak and how the meteors disperse.

The best view of the meteor shower will be to the north – northeast part of the sky.

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