Jupiter, I SEE U

Oct, 2011

2011 深秋十月的天象，木星(Jupiter)无疑是最佳目标，每天太阳落山后在西南方向木星是最显著的星(-4等),肉眼可见。

架好了器材，想试试auto-starGuide的功能好不好使，启动motor的时候发现镜筒升不上去，被支架卡住了，ZZ说是不是装反了，仔细一看，可不是。Rookie mistake...

加好了支架，用红外夜视瞄准镜（就是某些枪械上用的东东）对准西南方最亮的那颗星，放上25mm的目镜，开始搜索。别看已经用红外夜视镜确定了位置,但是想要在一个狭小的观测范围内找到目标不是一件轻松的事。开始调整的幅度比较大，左扭右恍的还是找不到。还是慢点儿吧，小心的左右上下移动，目标应该不会偏离太远。忽然目镜中出现一个很亮的点，调整了一下焦距，亮点越来越清晰，终于木星出现了（见插图, 目前还木有专门的相机，所以从网上抓了一个图。和当时看到的景色一模一样）。

Jupiter in a small telescope

木星表面大气的分层和他的四个主要卫星（IO, Europa, Ganymede,Callisto）清晰可见。想到现在看到的和几百年前伽利略用自制的望远镜第一次观测木星看到的一样的图画。想象伽利略当时瞪大的惊讶的眼神，还有我瞪大的眼睛；历史仿佛在这一瞬间连在了一起。后来换了9mm的目镜，木星的样子更加清晰的展现在我的眼前。ZZ也看到了木星的样子，很兴奋，连说这个望远镜是买值了。邻居出来遛狗也凑热闹看看，开玩笑说他看见了“外星人”...

Fast facts about Jupiter

• Jupiter is the largest planet in the solar system. More than 1,300 Earths could fit inside it, and all the other planets together make up only about 70 percent of Jupiter’s volume.
• It takes Jupiter about 12 years to orbit the Sun once, but only about 10 hours to rotate completely, making it the fastest-spinning of all the solar system’s planets.
• Jupiter rotates so rapidly that its polar diameter, 83,082 miles (133,708 kilometers), is only 93 percent of its equatorial diameter, 88,846 miles (142,984 km).
• Jupiter reflects 52 percent of the sunlight falling on it, more than any other planet except Venus (65 percent).
• Jupiter’s four large moons — Io, Europa, Ganymede, and Callisto — are easily visible through small telescopes. Io takes less than two days to orbit its planet, so its relative position visibly changes in an hour or so — less when it appears close to Jupiter.
• Our line of sight lies in the plane of the jovian moons’ orbits, so we see occultations (when a moon moves behind Jupiter), eclipses (when Jupiter’s shadow falls on a moon), and transits (when a moon passes in front of Jupiter) at various times.
• Jupiter’s moon Ganymede is the solar system’s largest satellite, with a diameter of nearly 3,300 miles (5,300 km), which is greater than that of Mercury.