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In this image released Thursday, Feb.
3, 2005, by NASA/JPL, a mosaic of 35 individual infrared
exposures made on Feb. 4, 2004, at the W.M. Keck I
Observatory, Mauna Kea, Hawaii, shows what scientists say are
the sharpest views of Saturn's temperature emissions ever
taken from the
ground.
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Astronomers using a giant telescope atop a volcano
have discovered a hot spot at the tip of Saturn's south pole. The
infrared images captured by
the Keck I telescope at the W.M. Keck Observatory atop Mauna Kea on the
Big Island suggest a warm polar vortex
- a large-scale weather pattern likened to a jet stream on
Earth that occurs in the upper atmosphere. It's the first such hot vortex
ever discovered in the solar system.
The team of scientists say the images are the sharpest thermal views of
Saturn ever taken from the ground. Their work will be published in
Friday's editions of the journal Science.
This warm polar cap is believed to contain the highest temperatures on
Saturn; the scientists did not give a temperature estimate.
On Earth, the Arctic Polar Vortex is typically located over eastern
North America in Canada and plunges cold arctic air to the northern Plains
in the United States.
Polar vortices are found on Earth, Jupiter, Mars and Venus, and are
colder than their surroundings. The new images from the Keck Observatory
show the first evidence of a polar vortex at much warmer temperatures.
"Saturn's is the first hot polar vortex that we've seen because it's
been sitting in the sunlight for about 18 years," said Glenn S. Orton, a
scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Saturn, which takes many earth years to orbit the sun, just had its
summer solstice in 2002.
"If the increased southern temperatures are solely the result of
seasonality, then the temperature should increase gradually with
increasing latitude, but it doesn't," Orton said. "We see that the
temperature increases abruptly by several degrees near 70 degrees south
and again at 87 degrees south.
Scientists may learn more from the data coming from the infrared spectrometer on the Cassini
spacecraft currently orbiting Saturn, Orton said.
(Reuters) |
天文学家们使用巨型望远镜在一座火山顶上观测太空，结果发现土星南极顶端有一个“热点”。凯克I望远镜位于夏威夷大岛基亚山顶的凯克天文台上，它捕捉到的红外线图像显示土星南极顶端有温暖的极地涡流。涡流是一种波及范围较广的天气形态，类似于地球高层大气中的急流。这是迄今为止人类第一次在太阳系里发现如此高温的涡流。
科学家小组表示，该图像是从地球上观察土星所能看到的最强烈的上升热气流。他们的研究结果将发表在周五出版的《科学》期刊上。
尽管科学家并未做出具体的气温评测，但他们相信这处“温暖”极冠包含着土星上的最高气温。
在地球上，北极的极地涡流主要集中在北美洲东部的加拿大，将寒冷的北极空气卷入美国北部平原。
人们在地球、木星、火星和金星上都发现了极地涡流，它们比周围的气候环境更冷。来自凯克天文台的新图像成为存在更温暖的极地涡流的最早的证据。
“人类在土星上发现了第一个温热的极地涡流，因为18年来它一直处在阳光照射下。”科学家格伦·S·奥顿说，他是美国宇航局喷气推进实验室（位于加州帕萨迪纳市）的科研人员。
土星绕太阳公转一周要花很多年的时间。2002年，土星刚刚度过了它的夏至。
奥顿说：“如果不断升高的南方气温仅仅是季节性变化的结果，那么气温应该随着纬度的增加逐渐升高，但事实却并非如此。我们发现温度在南纬70度附近突然升高了几度，同样的情况再次发生在87度附近。”
奥顿说，科学家们也许能从“卡西尼”太空船上的红外线分光计采集的数据中了解更多这方面的情况。“卡西尼”目前正围绕土星旋转。
（中国日报网站译） |
Updated: 2005-02-07 15:13