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Archive for June 30, 2012

NASA Explains Why Clocks Will Get An Extra Second On June 30


If the day seems a little longer than usual on Saturday, June 30, 2012, that’s because it will be. An extra second, or “leap” second, will be added at midnight to account for the fact that it is taking Earth longer and longer to complete one full turn—a day—or, technically, a solar day.

From VLBI, scientists have learned that Earth is not the most reliable timekeeper. The planet’s rotation is slowing down overall because of tidal forces between Earth and the moon. Roughly every 100 years, the day gets about 1.4 milliseconds, or 1.4 thousandths of a second, longer. Granted, that’s about 100 or 200 times faster than the blink of an eye. But if you add up that small discrepancy every day for years and years, it can make a very big difference indeed.

Full Story: http://www.nasa.gov/topics/solarsystem/features/extra-second.html

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Prediction System To Protect Astronauts From Solar Storms

June 30, 2012 1 comment

With the impending solar maximum expected to bring heightened rates of flares and coronal mass ejections (CMEs), putting at risk an ever-increasing human presence in space, Oh et al. designed and assessed a prediction system to keep astronauts safe from these solar storms. During a solar flare or CME, particles from the Sun can be accelerated to very high energies-in some cases travelling near the speed of light. Protons with energies surpassing 100 megaelectron volts essentially sandblast everything in their path. Though people on Earth are protected by the planet’s magnetic field and thick atmosphere, astronauts in spacecraft beyond low-Earth orbit, or people at high altitudes near the poles, can be exposed to this increased radiation. This can potentially cause radiation sickness, with symptoms such as fever and vomiting.

Full Story: http://www.agu.org/news/press/jhighlight_archives/2012/2012-06-29.shtml#two

Has The Speediest Pulsar Been Found?


NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton in space, and the Parkes radio telescope in Australia — may have found the fastest moving pulsar ever seen.

The large area of diffuse X-rays seen by XMM-Newton was produced when a massive star exploded as a supernova, leaving behind a debris field, or supernova remnant known as SNR MSH 11-16A. Shocks waves from the supernova have heated surrounding gas to several million degrees Kelvin, causing the remnant to glow brightly in X-rays.

The Chandra image reveals a comet-shaped X-ray source well outside the boundary of the supernova remnant. This source consists of a point-like object with a long tail trailing behind it for about 3 light years.

Full Story: http://www.nasa.gov/mission_pages/chandra/multimedia/fast_pulsar.html
Also: http://www.chandra.harvard.edu/photo/2012/igrj11014/