星系和彗星
(原标题: Galaxies and a Comet)
2023-10-20
浏览次数: 18
在这张10月12日拍摄于加州琼湖上空的清晰望远镜图像中，星系比比皆是。这幅天象横跨近2度，位于训练有素的北方天象星座的边界内。在距离我们2350万光年远的左上角，有一个巨大而美丽的螺旋星系NGC 4258，被一些人称为Messier 106。引人注目的边缘螺旋NGC 4217位于中央上方和右侧，距离我们约6000万光年。刚刚穿过这片美丽的视野的是彗星C/2023 H2莱蒙，它是去年4月在莱蒙山调查的图像数据中发现的。这颗彗星更像是一颗酸橙绿色的昏迷，伴随着一条微弱的、狭窄的离子尾巴向画面的顶部延伸。这颗内太阳系的访客目前距离我们不到7光分，用双筒望远镜仍然很难发现，但它正变得越来越亮。彗星C/2023 H2莱蒙将在10月29日到达近日点，也就是它离太阳最近的点，而在11月10日到达近地点，也就是它离我们美丽的星球最近的点，因为它将从早晨过渡到傍晚的北方天空。
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Galaxies abound in this sharp telescopic image recorded on October 12 in dark skies over June Lake, California. The celestial scene spans nearly 2 degrees within the boundaries of the well-trained northern constellation Canes Venatici. Prominent at the upper left 23.5 million light-years distant is big, beautiful spiral galaxy NGC 4258, known to some as Messier 106. Eye-catching edge-on spiral NGC 4217 is above and right of center about 60 million light-years away. Just passing through the pretty field of view is comet C/2023 H2 Lemmon, discovered last April in image data from the Mount Lemmon Survey. Here the comet sports more of a lime green coma though, along with a faint, narrow ion tail stretching toward the top of the frame. This visitor to the inner Solar System is presently less than 7 light-minutes away and still difficult to spot with binoculars, but it's growing brighter. Comet C/2023 H2 Lemmon will reach perihelion, its closest point to the Sun, on October 29 and perigee, its closest to our fair planet, on November 10 as it transitions from morning to evening northern skies.
© Dan Bartlett