李奥纳德彗星摇摆的彗尾

李奥纳德彗星摇摆的彗尾

ByNASA中文

2022年1月10日 Comet Leonard’s Tail Wag Image Credit: NASA, NRL, STEREO-A; Processing: B. Gallagher Explanation: Why does Comet Leonard’s tail wag? The featured time-lapse video shows the ion tail of Comet C/2021 A1 (Leonard) as it changed over ten days early last month. The video was taken by NASA’s Solar Terrestrial Relations Observatory-Ahead (STEREO-A) spacecraft that co-orbits the Sun at roughly the same distance as the Earth. Each image in this 29-degree field was subtracted from following image to create frames that highlight differences. The video clearly shows Comet Leonard’s long ion tail extending, wagging, and otherwise being blown around by the solar wind — a stream of fast-moving ions that stream out from the Sun. Since the video was taken, Comet Leonard continued plunging toward…

瓦尔帕罗拉山口上空的海尔-波普彗星

瓦尔帕罗拉山口上空的海尔-波普彗星

ByNASA中文

2021年12月08日 Comet Hale-Bopp Over Val Parola Pass Image Credit & Copyright: A. Dimai, (Col Druscie Obs.), AAC Explanation: Comet Hale-Bopp, the Great Comet of 1997, became much brighter than any surrounding stars. It was seen even over bright city lights. Away from city lights, however, it put on quite a spectacular show. Here Comet Hale-Bopp was photographed above Val Parola Pass in the Dolomite mountains surrounding Cortina d’Ampezzo, Italy. Comet Hale-Bopp’s blue ion tail, consisting of ions from the comet’s nucleus, is pushed out by the solar wind. The white dust tail is composed of larger particles of dust from the nucleus driven by the pressure of sunlight, that orbit behind the comet. Comet Hale-Bopp (C/1995 O1) remained visible to the unaided eye for 18…

NEOWISE彗星移动的彗尾

NEOWISE彗星移动的彗尾

ByNASA中文

2020年8月12日 The Shifting Tails of Comet NEOWISE Image Credit & Copyright: Ignacio Llorens Explanation: Keep your eye on the ion tail of Comet NEOWISE. A tale of this tail is the trail of the Earth. As with all comets, the blue ion tail always points away from the Sun. But as Comet C/2020 F3 (NEOWISE) rounded our Sun, its ion tail pointed in slightly different directions. This is because between 2020 July 17 and July 25 when the featured images were taken, the Earth moved noticeably in its orbit around the Sun. But the Earth’s motion made the Sun appear to shift in the sky. So even though you can’t see the Sun directly in the featured image(s), the directions of the ion tails reveal…

NEOWISE彗星的颀长彗尾

NEOWISE彗星的颀长彗尾

ByNASA中文

2020年7月16日 The Long Tails of Comet NEOWISE Image Credit & Copyright: Petr Horalek Explanation: This Comet NEOWISE (C/2020 F3) now sweeps through our fair planet’s northern skies. Its long tails stretch across this deep skyview from Suchy Vrch, Czech Republic. Recorded on the night of July 13/14, the composite of untracked foreground and tracked and filtered sky exposures teases out details in the comet’s tail not visible to the unaided eye. Faint structures extend to the top of the frame, over 20 degrees from the comet’s bright coma. Pushed out by the pressure of sunlight itself, the broad curve of the comet’s yellowish dust tail is easy to see by eye. But the fainter, more bluish tail is separate from the reflective comet dust. The…

NEOWISE彗星的彗尾

NEOWISE彗星的彗尾

ByNASA中文

2020年7月11日 The Tails of Comet NEOWISE Image Credit & Copyright: Miloslav Druckmuller (Brno University of Technology) Explanation: Comet NEOWISE (C/2020 F3) is now sweeping through northern skies. Its developing tails stretch some six degrees across this telescopic field of view, recorded from Brno, Czech Republic before daybreak on July 10. Pushed out by the pressure of sunlight itself, the comet’s broad, yellowish dust tail is easiest to see. But the image also captures a fainter, more bluish tail too, separate from the reflective comet dust. The fainter tail is an ion tail, formed as ions from the cometary coma are dragged outward by magnetic fields in the solar wind and fluoresce in the sunlight. In this sharp portrait of our new visitor from the outer…