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据美国《科学》杂志在线报道，该碎屑盘围绕着鲸鱼座中的一颗恒星运行(如图)。与众不同的是，碎屑盘的一侧比另一侧向太空中延伸了数千万公里，而计算机模型也无法模拟碎屑盘的形状和密度。研究人员推测，一些大质量的天体——很可能是另一颗恒星——最近从碎屑盘的附近掠过，从而将其向一端牵引，并最终减少了碎屑盘的密度。这幅合成图像是由美国宇航局(NASA)的哈勃望远镜和夏威夷的W.M. Keck天文望远镜共同拍摄的。

       今年7月11日，广州天文爱好者叶泉志(中山大学学生)和台湾鹿林天文台合作，发现了1颗新彗星，被国际天文联合会命名为“C／2007N3(Lulin)”彗星，这是广州天文爱好者首次发现的新彗星，也是我国天文爱好者第二次发现的新彗星。

　　当今，叶泉志是中国天文爱好者的一颗超新星。2005年10月，17岁的叶泉志就成为第1个发现NEAT小行星的中国人。2007年3月，叶泉志成为第1个获得了苏梅克近地天体奖的中国人和亚洲人。

　　叶泉志发现的C／2007N3新彗星有何特色，肉眼能不能看到？据广东天文学会的专家介绍：叶泉志发现新彗星的命名编号，C代表非周期彗星，N代表7月上半月。译成中文是“2007年7月上半月第3颗被确认的彗星，属非周期彗星”。

　　据测算，此彗星在2009年1月7日过近日点，距离太阳只有1.8亿公里；2月20日过近地点，距离地球只有0.6亿公里，亮度为5.9星等，肉眼勉强可见。如果借助双筒望远镜观察，这颗彗星就会尽收眼底。由于此彗星还有1年半的时间才能达到最明亮，届时亮度还会有新的变化，还会带来新的惊喜。

　　据悉，发现此彗星时，亮度为18.5等。目前，此彗星亮度已升至17等，采用口径400毫米的天文望远镜，可以目睹到这颗彗星的风采。

F rigid geysers are spewing material up through cracks in the crust of Pluto's companion Charon, recoating parts of its surface in ice crystals. These geysers could be turning this distant world into the equivalent of an outer solar system ice machine.

Evidence for these ice deposits comes from high-resolution spectra obtained using the Gemini Observatory's Adaptive Optics system, ALTAIR, coupled with near-infrared instrument NIRI. The observations, made with the Frederick C. Gillett Gemini North Telescope on Hawaii's Mauna Kea, show the fingerprints of ammonia hydrates and water crystals spread in patches across Charon, and are the best evidence yet for the existence of these compounds on worlds such as Charon.

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Like a hawk's eyes, the high resolution cameras on NASA's Cassini spacecraft have spotted yet another small, previously unknown moon circling giant Saturn and one which may indicate the existence of other small bodies in the same region. The tiny world--presently thought to be only about 2 kilometers (1 mile) wide--orbits at 197,700 kilometers (122,800 miles) from Saturn. Until a name for the moon is chosen by the International Astronomical Union, the moon has been given the provisional designation S/2007 S 4.

The moon was first spotted in Cassini images taken on May 30, 2007. Subsequent searches through images taken by Cassini over the previous three years turned up additional detections of the moon and helped researchers refine their calculations of its orbital path.

S/2007 S 4 orbits Saturn between the paths of Methone and Pallene, two small moons, about 4 kilometers (2.6 miles) wide, also discovered in Cassini images in 2004. All three moons orbit between much larger Mimas and Enceladus.

Moons surrounding the giant planets generally are not found where they originally formed because tidal forces from the planet can cause them to drift from their original locations. In drifting, they may sweep through 'resonances'--i.e., locations where other moons disturb them--and suffer orbit-changing perturbations. The new moon, like Methone, is in such a resonance with Mimas and appears to have undergone such an evolution.

"The fact that both Methone and S/2007 S 4 are dynamically locked with Mimas gives us a clue about their orbital history," said Carl Murray, a professor at Queen Mary, University of London, and the member of the Cassini Imaging Team leading the work on the new moon. "There are numerous examples of these resonant mechanisms between moons in the Saturn system and they probably arise due to tides. In the case of these two small moons, the resonance ensures that they cannot hit Mimas, at least in the short term."

Because the orbits of all three small moons lie close together, researchers think they may be remnants of a larger population.

"This trio of objects could be remnants of a collision or perhaps they are the lucky survivors of a larger population of material that failed to form a moon," said Murray. "Either way there does seem to be a family connection. If we could get good data about their surfaces with Cassini, we could begin to unravel some of these mysteries."

Cassini imaging scientists are already busy looking for future opportunities to zoom in on the new moon and refine its orbit, and to search for other companions.

"We've already identified times in the near future when we can take some pre-planned images and re-target them to get a closer look at this new body," said Carolyn Porco, imaging team leader and director of CICLOPS at the Space Science Institute. "And of course we're always on the lookout for additional moons. There are likely to be more of these very small bodies out there, and we hope to find them."

By chance, Cassini will approach the newly discovered moon at a distance of 11,700 kilometers (7,300 miles) at the end of December 2009, assuming the mission is extended beyond the summer of 2008, its nominal end. Images taken at that time could be useful for understanding the moon's shape, composition, and history.

Two NASA robots are surveying a rocky, isolated polar desert within a crater in the Arctic Circle. The study will help scientists learn how robots could evaluate potential outposts on the moon or Mars. The robots, K10 Black and K10 Red, carry 3-D laser scanners and ground-penetrating radar. The team arrived at Haughton Crater at Devon Island, Canada, on July 12 and will operate the machines until July 31.

Scientists chose the polar region because of the extreme environmental conditions, lack of infrastructure and resources, and geologic features. Additionally, Haughton Crater is geographically similar to Shackleton Crater at the South Pole of the moon. Both are impact craters that measure roughly 12.4 miles in diameter.

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编号为ＨＤ１８９７３３ｂ的行星

        在太阳系外一颗巨大气态行星的大气层中，充满高温水蒸气，这颗行星就像在“蒸桑拿”。这是一个国际天文学家小组的最新发现，也是天文学家首次有确凿证据表明太阳系外存在“水行星”。

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融合中的星系团

       北京时间7月20日消息　据国外媒体报道，借助XMM-牛顿和“钱德拉”红外望远镜，科学家们日前观测到了一次罕见的星系碰撞现象。

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        据国外媒体7月20日报道，天文学家表示，又一个新的土星卫星被发现了，至此，土星卫星凑齐了60个。

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