影片：李奥纳德彗星的一小时

影片：李奥纳德彗星的一小时

ByNASA中文

2022年1月25日 Video: Comet Leonard over One Hour Video Credit & Copyright: Matipon Tangmatitham (NARIT); Text: Matipon Tangmatitham Explanation: Which direction is this comet heading? Judging by the tail, one might imagine that Comet Leonard is traveling towards the bottom right, but a full 3D analysis shows it traveling almost directly away from the camera. With this perspective, the dust tail is trailed towards the camera and can only be seen as a short yellow-white glow near the head of the comet. The bluish ion tail, however, is made up of escaping ions that are forced directly away from the Sun by the solar wind — but channeled along the Sun’s magnetic field lines. The Sun’s magnetic field is quite complex, however, and occasionally solar magnetic…

摄于澳洲的李奥纳德彗星特写

摄于澳洲的李奥纳德彗星特写

ByNASA中文

2022年1月12日 Comet Leonard Closeup from Australia Image Credit & Copyright: Blake Estes (itelescope.net) Explanation: What does Comet Leonard look like up close? Although we can’t go there, imaging the comet’s coma and inner tails through a small telescope gives us a good idea. As the name implies, the ion tail is made of ionized gas — gas energized by ultraviolet light from the Sun and pushed outward by the solar wind. The solar wind is quite structured and sculpted by the Sun’s complex and ever changing magnetic field. The effect of the variable solar wind combined with different gas jets venting from the comet’s nucleus accounts for the tail’s complex structure. Following the wind, structure in Comet Leonard’s tail can be seen to move outward…

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…

李奥纳德彗星的长尾

李奥纳德彗星的长尾

ByNASA中文

2022年1月3日 Comet Leonard’s Long Tail Image Credit & Copyright: Jan Hattenbach Explanation: You couldn’t see Comet Leonard’s extremely long tail with a telescope — it was just too long. You also couldn’t see it with binoculars — still too long. Or with your eyes — it was too dim. Or from a city — the sky was too bright. But from a dark location with a low horizon — your camera could. And still might — if the comet survives today’s closest encounter with the Sun, which occurs between the orbits of Mercury and Venus. The featured picture was created from two deep and wide-angle camera images taken from La Palma in the Canary Islands of Spain late last month. Afterwards, if it survives, what…

李奥纳德彗星的超长彗尾

李奥纳德彗星的超长彗尾

ByNASA中文

2021年12月30日 The Further Tail of Comet Leonard Image Credit & Copyright: Daniele Gasparri Explanation: Comet Leonard, brightest comet of 2021, is at the lower left of these two panels captured on December 29 in dark Atacama desert skies. Heading for its perihelion on January 3 Comet Leonard’s visible tail has grown. Stacked exposures with a wide angle lens (also displayed in a reversed B/W scheme for contrast), trace the complicated ion tail for an amazing 60 degrees, with bright Jupiter shining near the horizon at lower right. Material vaporizing from Comet Leonard’s nucleus, a mass of dust, rock, and ices about 1 kilometer across, has produced the long tail of ionized gas fluorescing in the sunlight. Likely flares on the comet’s nucleus and buffeting by…

詹姆斯·韦伯太空望远镜发射烟尘后方的李奥纳德彗星

詹姆斯·韦伯太空望远镜发射烟尘后方的李奥纳德彗星

ByNASA中文

2021年12月27日 Comet Leonard behind JWST Launch Plume Image Credit & Copyright: Matipon Tangmatitham (NARIT) Explanation: Which one of these two streaks is a comet? Although they both have comet-like features, the lower streak is the only real comet. This lower streak shows the coma and tail of Comet Leonard, a city-sized block of rocky ice that is passing through the inner Solar System as it continues its looping orbit around the Sun. Comet Leonard has recently passed its closest to both the Earth and Venus and will round the Sun next week. The comet, still visible to the unaided eye, has developed a long and changing tail in recent weeks. In contrast, the upper streak is the launch plume of the Ariane V rocket that…

圣诞彗星的彗尾

圣诞彗星的彗尾

ByNASA中文

2021年12月25日 The Tail of a Christmas Comet Image Credit & Copyright: Rolando Ligustri (CARA Project, CAST) and Lukas Demetz Explanation: The tail of a comet streams across this three degree wide telescopic field of view captured under dark Namibian skies on December 21. In outburst only a few days ago and just reaching naked eye visibility Comet Leonard (C/2021 A1) is this year’s brightest comet. Binoculars will make the diffuse comet easier to spot though, close to the western horizon after sunset. Details revealed in the sharp image show the comet’s coma with a greenish tinge, and follow the interaction of the comet’s ion tail with magnetic fields in the solar wind. After passing closest to Earth on December 12 and Venus on December 18,…

三行星与一颗彗星

三行星与一颗彗星

ByNASA中文

2021年12月23日 Three Planets and a Comet Image Credit & Copyright: Tunc Tezel (TWAN) Explanation: Are you still looking for that perfect holiday gift for an astronomer? If your night sky is dark and horizon clear enough, the Solar System may have done your shopping for you. Send them outside after sunset to see three planets and a comet. In this snapshot of the December solstice evening sky from the village of Kirazli, Turkey the brightest celestial beacon is Venus, close to the southwestern horizon at the right. Look left and up to find Saturn shining between clouds. Follow that line farther left and up to bright Jupiter, the Solar System’s ruling gas giant. This year’s surprise visitor to the inner Solar System, Comet Leonard (C/2021…

彗星与火流星

彗星与火流星

ByNASA中文

2021年12月20日 The Comet and the Fireball Image Credit & Copyright: Cory Poole Explanation: This picture was supposed to feature a comet. Specifically, a series of images of the brightest comet of 2021 were being captured: Comet Leonard. But the universe had other plans. Within a fraction of a second, a meteor so bright it could be called a fireball streaked through just below the comet. And the meteor’s flash was even more green than the comet’s coma. The cause of the meteor’s green was likely magnesium evaporating from the meteor’s pebble-sized core, while the cause of the comet’s green was likely diatomic carbon recently ejected from the comet’s city-sized nucleus. The images were taken 10 days ago over the Sacramento River and Mt. Lassen in…

从太空看李奥纳德彗星

从太空看李奥纳德彗星

ByNASA中文

2021年12月15日 Comet Leonard from Space Image Credit & Copyright: Zhuoxiao Wang, Yangwang-1 Space Telescope, Origin.Space Explanation: What does Comet Leonard look like from space? Today’s featured image from Origin.Space’s Yangwang-1 space telescope shows not only the currently bright comet — but several other space delights as well. Taken in optical and ultraviolet light, C/2021 A1 (Leonard) is visible with an extended tail near the image center as it appeared five days ago. The Earth is visible on the lower right, while layers of the Earth’s atmosphere glow diagonally from the lower left to the upper right. The trails of two satellites can be seen in front of a myriad of distant stars that dot the background on the upper left. The faint bands of light…