November 3, 2006
Fantastic Images of the Sun
The Solar Optical Telescope (SOT) onboard Japan's Hinode spacecraft has opened its doors and started snapping pictures. Shown below is a "first light" image taken Oct. 23rd. The light and dark blobs are solar granules, masses of hot gas that rise and fall like water boiling atop a hot stove. Each granule is about the size of a terrestrial continent. SOT has no trouble seeing such detail from Earth-orbit 93 million miles away.
"We have confirmed that SOT is achieving a very high angular resolution of 0.2 arcseconds, a primary objective of the instrument," says the Japan Aerospace Exploration Agency (JAXA) in a statement released Oct. 31st. One arcsecond is an angle equal to 1/3600 of a degree"”or approximately the width of a human hair held thirty feet away.Hinode (Japanese for Sunrise, formerly known as Solar B) was launched on Sept 22nd from the Uchinoura Space Center in Kyushu, Japan. "It's on a mission to study the sun"”specifically sunspots, which give rise to powerful flares and solar storms," says John Davis, the NASA Solar-B project scientist at NASA's Marshall Space Flight Center. Astronomers have been studying sunspots since the days of Galileo four hundred years ago, but they still don't know how to predict flares. Data from Hinode may solve the mystery.
Hinode carries three advanced space telescopes:
The Solar Optical Telescope (SOT) provides crystal-clear images of features on the sun's surface. A vector magnetograph attached to the SOT will be able to trace sunspot magnetic fields, which harbor energy for explosive flares. (Engineers are still bringing the vector magnetograph online.)
The X-ray telescope (XRT) can see million-degree gas caught in the magnetic grip of sunspots and, higher up, floating in the sun's atmosphere, the corona. For reasons no one understands, the sun's corona is much hotter than the sun's surface"”another mystery Hinode may help solve. First light for the XRT was achieved on Oct 25th: image.
The Extreme Ultraviolet Imaging Spectrometer (EIS) is a device that can tune into specific spectral lines emitted by ions in the sun's atmosphere. By watching these lines shift back and forth (the Doppler Shift), astronomers can keep track of solar material as it moves around. Dynamic movies from the EIS will not only entertain, but also provide crucial clues to solve the dual mystery of flares and coronal heating. First light for the EIS was obtained on October 28th