Nothing But Rings
August 11th, 2006
This photograph is a close-up view of Saturn’s A ring taken by Cassini. Look closely and you’ll see that the dark regions appear to widen and then narrow, and the thin bright regions disappear altogether. Cassini took this image on July 23, 2006 when it was 285,000 kilometers (177,000 miles) from Saturn.
Hourglass-Shaped Magnetic Field Discovered
August 11th, 2006
Astronomers have finally discovered an object that has long been theorized: an hourglass-shaped magnetic field in a star forming region. The field is located in the protostellar system NGC IRAS 4A, which is located about 980 light-years from Earth in the constellation Perseus. Theorists predicted that the magnetic fields of collapsing clouds of gas and dust would form this hourglass shape because of the competing forces of magnetism and gravity.
Book Review: Beyond Earth
August 10th, 2006
Does humanity have a destiny? Are we to accomplish a task before ending as a species, or do we perhaps continue on, ever evolving and exploring? The explorers amongst us certainly want to continue, and their hopes are pointedly directed to the stars. The book Beyond Earth is a compilation of essays from visionaries who are committed to achieving this goal. Their ideas and plans show a decided conviction on a destiny that includes advancing our frontier off of Earth.
Satellites Measure Melting Greenland Ice
August 10th, 2006
NASA’s GRACE satellites have measured an increasing rate of ice melt in Greenland. According to new analysis by researchers at the University of Arizona at Austin, the loss of ice from Greenland’s southeastern region has sped up between 2002 and 2005. Approximately 239 cubic kilometers (57 cubic miles) is now lost each year. Greenland contains 10% of the Earth’s fresh water, and this melting ice is contributing 0.56 mm (.02 inches) to globally rising sea levels.
James Van Allen Dies
August 9th, 2006
Renowned space scientist Dr. James A. Van Allen died this morning at the age of 91. Although he had a lifetime’s worth of contributions to astronomy, space science and space exploration, Dr. Allen was best known for his discovery of the radiation belts that surround the Earth. An experiment he designed for the spacecraft Explorer 1 gauged the Van Allen belts using tiny Geiger counters to measure radiation. He retired from full time teaching at the University of Iowa in 1985, but continued to write, oversee research, and monitor data sent back by spacecraft he was involved with.
Astrophoto: The Bubble Nebula (NGC 7635) by Karel Teuwen
August 9th, 2006
Every clear evening, as twilight dissolves into night, untold thousands of telescopes scattered across the globe turn toward the great beyond that lies above. But, increasingly, a camera is replacing the eyepiece as the favorite way to study the heavens. Taking deep space pictures was once the purview of a small, dedicated group of amateur astronomers. The technology available was daunting, expensive and time consuming. Luck was an important factor in producing an image that resembled its subject. But all that has changed in the past few years- producing deep space images, such as the one seen here, while still not a point-and-click exercise, has become much easier.
Rigel Passes Behind Saturn
August 8th, 2006
NASA’s Cassini spacecraft captured this image of the star Rigel passing behind Saturn’s atmosphere. Rigel is well known to astronomers, as one of the brightest stars in the constellation of Orion. This event allows Cassini to measure the haze structure and opacity of Saturn’s upper atmosphere as the star is dimmed. Cassini took this image on June 30, 2004 when it was 446,000 kilometers (277,000 miles) from Saturn.
Washed Out Perseids Will Peak on Friday
August 8th, 2006
One of the best meteor showers of the year - the Perseids - will get washed out by a nearly full Moon this year. But that doesn’t mean you shouldn’t try and enjoy them anyway. The Moon will be 87% full on Friday, August 11, rising after 10:00pm. Head out after it goes dark, and see if you can spot an Earth grazer; a special kind of meteor that can be very bright and slow, leaving a dramatic tail. After 10:00pm, only the brightest meteors will be visible. 2007 will be much better, when it’ll be a moonless sky.
Chandra Confirms the Hubble Constant
August 8th, 2006
Nearly every single astronomical measurement depends on the Hubble constant, a number that calculates the expansion of the Universe. NASA’s Chandra X-Ray Observatory recently measured this value independently, and came up with a similar number - 77 km per second per megaparsec (3.26 million light-years to the megaparsec). Give or take 15%. This confirms that the Universe is still between 12 and 14 billion years old.
Hubble Finds an Exoplanet’s Parent Star
August 8th, 2006
When a star flared briefly, astronomers knew it was because a dimmer star had passed directly in front, acting as a lens with its gravity to focus light. Unfortunately, they couldn’t find the star. This was important, because the brief microlensing event also turned up the fact that this lensing star has a planet. Astronomers have used the power of the Hubble Space Telescope to find this dim star two years after the lensing event. Identifying the star is critical, because it allows astronomers to measure its unique characteristics, such as mass, temperature and composition.
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