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.
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Rigel Passes Behind Saturn
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.
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Washed Out Perseids Will Peak on Friday
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.
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Chandra Confirms the Hubble Constant
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.
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Hubble Finds an Exoplanet’s Parent Star
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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What’s Up this Week: August 7 – August 13, 2006
Greetings, fellow SkyWatchers! The week begins with the Moon and ends up going globular as we have a look at some of the finest the Summer has to offer. Although skies will be bright, don’t forget the most reliable meteor shower of all – the Perseids! Hang around to explore multiple star systems because…
Here’s what’s up!
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Enceladus Occults Rhea
NASA’s Cassini spacecraft captured this photograph of Saturn’s moon Rhea emerging from behind another of its moons, Enceladus. At 1,528 km (949 miles) across, Rhea is actually three times larger than Enceladus (505 km or 314 miles), but Cassini was much closer to Enceladus when it captured this occultation event on July 4, 2006.
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Constant Rain of Space Dust Adds Up
A slow, steady rain of cosmic space dust is always falling through the Earth’s atmosphere. These particles from space are infused with a rare isotope of helium that makes it immediately identifiable compared to a more common isotope of helium we find here on Earth. Scientists recently drilled an ice core in Antarctica containing a record of this dust fall that goes back 30,000 years. This new data gives scientists another line of data to study global climate history as the ratio between the isotopes varies between interglacial periods.
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The Universe Could Be Larger Than Previously Thought
Astronomers recently calculated the distance to the relatively nearby galaxy M33 (aka the Triangulum Galaxy) as being about 15% further than previously estimated. They analyzed the distance using several telescopes, fine tuning their instruments very carefully. This measurement means that the Hubble constant – which astronomers use to measure distances in the Universe – could be off as well. The Universe might actually be 15% larger than previously believed.
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Proton Launches Eutelsat Satellite
A Proton Breeze M rocket blasted off from the Baikonur Cosmodrome on Friday night, carrying the Eutelsat Hot Bird 8 broadcast satellite. The rocked lifted off at 2148 GMT (5:48 pm EDT), and released its satellite into a geosynchronous transfer orbit about 9 hours later. Hot Bird 8 will provide broadcast television to customers in Europe, the Middle East, and North Africa.
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