Hubble finds new Neptune moon: NASA

Hubble finds new Neptune moon: NASA

U.S. space agency NASA said Monday its Hubble Space Telescope has found a new moon orbiting the distant blue-green planet Neptune, the 14th known to be circling the giant planet.

The moon, designated S/2004 N 1, is estimated to be no more than 12 miles (19 kilometers) across, making it the smallest known moon in the Neptunian system, NASA said.

It is so small and dim that it is roughly 100 million times fainter than the faintest star that can be seen with the naked eye, and it even escaped detection by NASA's Voyager 2 spacecraft, which flew past Neptune in 1989 and surveyed the planet's system of moons and rings, the agency said.

Mark Showalter of the U.S. nonprofit science research group SETI Institute found the moon on July 1, while studying the faint arcs, or segments of rings, around Neptune.

"The moons and arcs orbit very quickly, so we had to devise a way to follow their motion in order to bring out the details of the system," he said in a statement. "It's the same reason a sports photographer tracks a running athlete -- the athlete stays in focus, but the background blurs."

The method involved tracking the movement of a white dot that appears over and over again in more than 150 archival Neptune photographs taken by Hubble from 2004 to 2009.

Showalter noticed the white dot about 65,400 miles (one million kilometers) from Neptune located between the orbits of the Neptunian moons Larissa and Proteus. Showalter plotted a circular orbit for the moon, which completes one revolution around Neptune every 23 hours, NASA said.

海王星又添一顆小衛(wèi)星

新華網(wǎng)華盛頓７月１５日電（記者林小春）美國航天局１５日宣布,"哈勃"太空望遠(yuǎn)鏡發(fā)現(xiàn)了海王星的又一顆衛(wèi)星.至此,海王星擁有的衛(wèi)星數(shù)量上升至１４顆.

美國航天局當(dāng)天發(fā)表聲明說,這顆衛(wèi)星直徑不超過１９公里,是海王星所有衛(wèi)星中最小的.它在距海王星約１０５萬公里的圓形軌道上運(yùn)轉(zhuǎn),周期為２３小時.它的亮度比我們從地球上肉眼能看到的最暗淡的星星還要弱一億倍,以至于１９８９年"旅行者"２號探測器飛經(jīng)海王星時,也沒有發(fā)現(xiàn)它.

有趣的是,"哈勃"太空望遠(yuǎn)鏡其實(shí)９年前就抓拍到它的蹤影,但直到本月１日,美國科研組織"搜尋外星文明研究所"的馬克·肖沃爾特在研究海王星的弧段數(shù)據(jù)時,才偶然發(fā)現(xiàn)它的存在.

在"哈勃"拍到的照片上,這顆衛(wèi)星呈現(xiàn)為一個白點(diǎn).進(jìn)一步分析發(fā)現(xiàn),２００４年至２００９年間,共有１５０多張"哈勃"拍攝的海王星照片上存在這個白點(diǎn)."誰都可能成為這顆衛(wèi)星的發(fā)現(xiàn)者,"肖沃爾特說.