Gliding through the stars, Comet C/2025 R2 (SWAN) displays a bright cyan coma and a strikingly long, detailed ion tail in this image from September 16, 2025. The comet’s tail is shaped by the solar wind, with intricate kinks and disconnections revealing real-time interactions between the comet’s plasma and the charged particles streaming from the Sun. The vivid greenish hue of the coma comes from diatomic carbon fluorescing under sunlight.

Captured with careful tracking to follow the comet’s motion, the image reveals both the fine filamentary structure of the tail and the sharp star field beyond. The scene is a reminder that comets are dynamic travelers, changing in brightness and appearance as they approach and recede from the Sun.

On the night of May 1, two tiny comets made a close encounter in the Earth's night sky. The smaller one on the left is C/2020 T2 Palomar, while the larger one on the right is C/2020 R4 ATLAS. In fact, they were still hundreds of millions of kilometers apart but happened to appear in the same direction of the Earth's perspective. The two comets went their separate ways soon after, and it will be a long time before they meet each other again.
Location: Galaxy Remote Observatory, Kangbao, Hebei, China
Time: May 1, 2020
Telescope: SharpStar 150 2.8 HNT
Camera: QHY268C
Mount: iOptron CEM60
Guide: QHYCCD OAG-M
Guide camera: QHY5L-II-M
Frames: 139×30 seconds
Integration: 1.2 hours
Acquired by APT
Processed by PixInsight and PhotoShop

Copyright: [Steed Yu][1]