Academic journal article
By Wilkinson, John
Teaching Science , Vol. 58, No. 4
There's always something new happening in the field of Astronomy. This includes the immediate environment surrounding Earth, the Solar system and the universe. This article looks at some of the recent research astronomers have been undertaking this year. Each article has reference to a web site so teachers can find out more information or ask their students to investigate further.
MORE METHANE ON TITAN
NASA's Cassini spacecraft has found long-standing methane lakes in the 'tropics of Saturn's moon, Titan. One of the tropical lakes appears to be about half the size of Utah's Great Salt Lake, with a depth of at least one metre. The result, which is a new analysis of Cassini data, is unexpected because models had assumed the longstanding bodies of liquid would only exist at the poles.
Understanding how lakes or wetlands form on Titan helps scientists learn about the moon's weather. Like Earth's hydrological cycle, Titan has a 'methane' cycle, with methane rather than water circulating. in Titan's atmosphere, ultraviolet light breaks apart methane, initiating a chain of complicated organic chemical reactions. But existing models haven't been able to account for the abundant supply of methane. Methane is a progenitor of Titan's organic chemistry, which likely produces interesting molecules like amino acids, the building blocks of life.
Global circulation models of Titan have theorised that liquid methane in the moon's equatorial region evaporates and is carried by wind to the north and south poles, where cooler temperatures cause methane to condense. When it falls to the surface, it forms the polar lakes.
The latest results come from Cassini's visual and infrared mapping spectrometre, which detected the dark areas in the tropical region known as Shangri-La, near the spot where the European Space Agency's Huygens probe landed in 2005. When Huygens landed, the heat of the probe's lamp vaporized some methane from the ground, indicating it had landed in a damp area.
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory manages the mission for NASA's Science Mission Directorate, Washington. The visual and infrared mapping spectrometre team is based at the University of Arizona, Tucson. See photo 1.
More Cassini information is available at http://www. nasa.gov/cassini and http://saturn.jpl.nasa.gov.
ULTRA FINE LOOPS IN THE SUN'S CORONA
A key to understanding the dynamics of the sun and what causes the great solar explosions there, relies on deciphering how material, heat and energy swirl across the sun's surface and rise into the upper atmosphere, or corona. Tracking the constantly moving material requires state-of-the-art telescopes with the highest resolution possible. By combining images from NASA's Solar Dynamics Observatory (S DO) and a new generation telescope called the New Solar Telescope (NST) at Big Bear Solar Observatory in Big Bear City, California, scientists have for the first time observed a new facet of the system: especially narrow loops of solar material scattered on the sun's surface, which are connected to higher lying, wider loops. These ultra fine loops and their wider cousins may also help with the quest to determine how temperatures rise throughout the corona. According to a paper in the Astrophysical Journal on May 1, 2012, the loops are ten times narrower and at least ten times cooler than the higher loops often seen by SDO.
Magnetic maps produced by the researchers showed that the loops lined up with fine lanes on the sun that separate what's known as granules--cells on the star's surface that can be loosely understood as bubbles of boiling solar material that rise up from below. After the material, or plasma, rises up into the granules, it sweeps out to the sides, and flows back down these intergranular lanes. …