摘要

North Pole Grid	South Pole Grid

PIA09257: Io in Motion
Io is the most volcanically active body in the Solar System. Volcanoes erupt massive volumes of silicate lava, sulphur and sulphur dioxide, constantly changing Io's appearance. This new basemap of Jupiter's moon Io was produced by combining the best images from both the Voyager 1 and Galileo Missions. Although the subjovian hemisphere of Io was poorly seen by Galileo, superbly detailed Voyager 1 images cover longitudes from 240 W to 40 W and the nearby southern latitudes. A monochrome mosaic of the highest resolution images from both Galileo and Voyager 1 was assembled that includes 51 Voyager 1 images with spatial resolutions sometimes exceeding the 1 km/pixel scale of the final mosaic. Because this mosaic is made up of images taken at various local times of day, care must be taken to note the solar illumination direction when deciding whether topographic features display positive or negative relief. In general, the illumination is from the west over longitudes 40 to 270 W, and from the east over longitudes 270 W to 40 W. Color information was later superimposed from Galileo low phase angle violet, green, and near-infrared (756 nanometer wavelength) images. The Galileo SSI camera's silicon CCD was sensitive to longer wavelengths than the vidicon cameras of Voyager, so that distinctions between red and yellow hues can be more easily discerned. The "true" colors that would be visible to the eye are similar but much more muted than shown here. Image resolutions range from 1 to 10 km/pixel along the equator, with the poorest coverage centered on longitude 50 W.

This mosaic is in an equal area cylindrical map projection, centered onlongitude 180, with grid lines at 30 degree intervals. Full scale versions of this mosaic, and the data products used to generate it, can be obtained from the USGS Astrogeology website, https://astrogeology.usgs.gov/Projects/JupiterSatellites/.

About the Animation

Animation file: Image:Iorotateing1day.ogg

In the same way that the Moon always has the same side facing Earth, Io always has the same side facing Jupiter. The movie shows two speeded-up rotations of Io (a single rotation really takes 1.77 days), and begins with a view of the Jupiter-facing hemisphere. With rotation in an easterly direction, after two seconds the volcano Prometheus (on the equator) comes into view. The massive red deposit around Pele (seconds 5-10) is the most distinctive expression of volcanic activity on Io, and just to the north-west is the horse shoe-shaped Loki Patera, the most powerful volcano on Io.

The animation was made using a computer program that wrapped the Io mosaic around a sphere to produce a globe. In all, 360 images were used, each differing by one degree in longitude from the previous image.

Source: http://photojournal.jpl.nasa.gov/catalog/PIA09257 (direct link)

本图像或视频收录于美国国家航空航天局 （NASA）喷气推进实验室（Jet Propulsion Laboratory），其照片编号是： PIA09257 此标签不表示文件的著作权状态。任何文件在附有此标签的同時还需要一个有效的著作权标签。请参阅许可协议说明页面以了解更多信息。 其他语言： العربية ∙ беларуская (тарашкевіца) ∙ български ∙ català ∙ čeština ∙ dansk ∙ Deutsch ∙ English ∙ español ∙ فارسی ∙ français ∙ galego ∙ magyar ∙ հայերեն ∙ Bahasa Indonesia ∙ italiano ∙ 日本語 ∙ македонски ∙ മലയാളം ∙ Nederlands ∙ polski ∙ português ∙ русский ∙ sicilianu ∙ slovenščina ∙ Türkçe ∙ українська ∙ 简体中文 ∙ 繁體中文 ∙ +/−

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