庞士-布鲁克斯彗星指向相反的彗尾

庞士-布鲁克斯彗星指向相反的彗尾

Comet Pons-Brooks Develops Opposing Tails
Image Credit & Copyright: Rolando Ligustri & Lukas Demetz

Explanation: Why does Comet Pons-Brooks now have tails pointing in opposite directions? The most spectacular tail is the blue-glowing ion tail that is visible flowing down the image. The ion tail is pushed directly out from the Sun by the solar wind. On the upper right is the glowing central coma of Comet 12P/Pons–Brooks. Fanning out from the coma, mostly to the left, is the comet’s dust tail. Pushed out and slowed down by the pressure of sunlight, the dust tail tends to trail the comet along its orbit and, from some viewing angles, can appear opposite to the ion tail. The distant, bright star Alpha Leporis is seen at the bottom of the featured image captured last week from Namibia. Two days ago, the comet passed its closest to the Earth and is now best visible from southern skies as it dims and glides back to the outer Solar System.

Tomorrow’s picture: mystery martian

庞士-布鲁克斯彗星指向相反的彗尾
影像提供与版权: Rolando Ligustri & Lukas Demetz

说明: 为何庞士-布鲁克斯彗星的彗尾现在的指向相反？它最壮观的彗尾，是向影像下方流泛、受到太阳风的推动而指离太阳的泛蓝离子尾。而在影像右上角，可见到庞士-布鲁克斯彗星（12P/Pons–Brooks）的明亮彗发。此外，还有从彗发伸出基本指向左侧的扇形尘尾。受到太阳光压推动和减速的尘尾，通常落在彗星后方的轨道上，而从某些视角观看，有时看似与离子尾的指向相反。在这幅上星期摄于纳米比亚的主题影像之底缘附近，还可见看到遥远且明亮的厕一（天免座α星）。两天前，这颗目前最佳观测位地点在南半球的彗星，掠过了离地球最近的位置，并随着它滑向太阳系外围而不断的变暗。

明日的图片: mystery martian