astronomy

Geodynamo: Building a Test Planet

Posted Thu, 01/15/2009 - 19:16 by Nick Winterhalter
A482E5E3-E2B1-415F-BC58-9CA42FED8BCB.jpg
(Click for video)

Researchers at the University of Maryland have constructed a 30-ton sphere that spins at more than 90 mph to generate magnetic fields. The 10-ft.-dia. sphere is filled with 13.5 tons of liquid sodium to mimic the Earth’s liquid-iron center core. A 3.3-ft.- dia. stainless-steel sphere inside the larger one counterrotates to approximate the motion of the planet’s solid iron inner core. The action of Earth’s inner liquid produces a magnetic field that makes compasses work, deflects harmful cosmic rays and protects the planet from solar wind. The field reverses every couple of hundred thousand years. By using a model instead of a computer simulation, scientists hope to determine how these reversals occur and predict the next one.

Via Popular Mechanics

Solargraph

Posted Thu, 01/15/2009 - 11:13 by Nick Winterhalter

If every picture tells a story, this one might make a novel. The six month long exposure compresses the time from December 17, 2007 to June 21, 2008 into a single point of view. Dubbed a solargraph, the remarkable image was recorded with a simple pinhole camera made from a drink can lined with a piece of photographic paper. The Clifton Suspension Bridge over the Avon River Gorge in Bristol, UK emerges from the foreground, but rising and setting each day the Sun arcs overhead, tracing a glowing path through the sky. Cloud cover causes dark gaps in the daily Sun trails. In December, the Sun trails begin lower down and are short, corresponding to a time near the northern hemisphere's winter solstice date. They grow longer and climb higher in the sky as the June 21st summer solstice approaches.

Via Astronomy Picture of the Day
Photo by Justin Quinnell

Predicting the Existence of Neptune

Posted Tue, 09/23/2008 - 11:25 by Nick Winterhalter
613AA3FF-BCCC-4B3E-BC0F-225A479643F9.jpg 3B9A3306-53EF-4CFA-AA7A-EC7D990BE87B.jpg
Neptune and Triton — Image credit: NASA/JPL

1846: German astronomer Johann Gottfried Galle, knowing exactly where to look, confirms the existence of an eighth planet in the solar system, Neptune.

Galle was not the first astronomer to see Neptune -- Galileo, puzzled by the changing position of what he thought was a fixed star, had sketched the movement in 1613 but never published his findings. Others had seen it, too, but Galle, working at the Berlin Observatory, was the first to observe Neptune while understanding exactly what he was looking at.

By the time Galle fixed his gaze upon Neptune, the existence of a planet beyond Uranus was widely predicted and its position had been intensely calculated. In fact, other astronomers were quarreling over who owned the priority of discovery.

Link to Wired article by Tony Long

Galaxy's Youngest Supernova Remnant

Posted Wed, 05/14/2008 - 12:15 by Nick Winterhalter

At just 140 years old, this recently discovered supernova remnant is the youngest yet found. Obscured by dust until X-ray and radio telescopes revealed it, "G1.9+0.3" came into being shortly after the United States' Civil War.

200807251129.jpg

Supernova remnants are caused when the debris thrown outwards by the explosion crashes into surrounding material, generating a shell of hot gas and high-energy particles that glows brightly in X-rays, radio waves and other wavelengths for thousands of years. In the case of G1.9+0.3 the material is expanding outwards at almost 35 million miles per hour, or about 5% the speed of light, an unprecedented expansion speed for a supernova remnant. Another superlative for G1.9+0.3 is that it has generated the most energetic electrons ever seen in a supernova remnant.

Link to Chandra X-Ray Observatory article

The Channels of Mars

Posted Tue, 04/22/2008 - 18:47 by Nick Winterhalter

The myopic and colour blind Schiaparelli (neither of which, in all seriousness, hampered his renown as a meticulously observant astronomer) included in his map -- which he continued to augment all through the 1880s, and which served as the cartographic authority on the Martian landscape in planetary astronomy for two decades -- linear features that he saw criss-crossing the surface of Mars, which he referred to as 'canali'. This Italian word translates to English as either 'channels' or 'canals', and although Schiaparelli was implying the more naturalistic descriptor, 'channels', somehow 'canals' became the accepted terminology.

666813BE-4133-4854-BC41-B9A07364DE96.jpg

Via Bibliodyssey