双子流星雨

双子流星雨

ByNASA中文

2021年11月16日 Geminids from Gemini Image Credit & Copyright: Wang Jin Explanation: Where are all of these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Gemini. That is why the major meteor shower in December is known as the Geminids — because shower meteors all appear to come from a radiant toward Gemini. Three dimensionally, however, sand-sized debris expelled from the unusual asteroid 3200 Phaethon follows a well-defined orbit about our Sun, and the part of the orbit that approaches Earth is superposed in front of the constellation of Gemini. Therefore, when Earth crosses this orbit, the radiant point of falling debris appears in Gemini. Featured here, a composite of many images taken during the 2020 Geminids…

加拿大路易斯湖上空的火流星

加拿大路易斯湖上空的火流星

ByNASA中文

2021年10月12日 Fireball over Lake Louise Image Credit & Copyright: Hao Qin Explanation: What makes a meteor a fireball? First of all, everyone agrees that a fireball is an exceptionally bright meteor. Past that, the International Astronomical Union defines a fireball as a meteor brighter than apparent magnitude -4, which corresponds (roughly) to being brighter than any planet — as well as bright enough to cast a human-noticeable shadow. Pictured, an astrophotographer taking a long-duration sky image captured by accident the brightest meteor he had ever seen. Clearly a fireball, the disintegrating space-rock created a trail so bright it turned night into day for about two seconds earlier this month. The fireball has been artificially dimmed in the featured image to bring up foreground Lake Louise…

星系与宇宙沙粒

星系与宇宙沙粒

ByNASA中文

2021年8月14日 Island Universe, Cosmic Sand Image Credit & Copyright: Marzena Rogozinska Explanation: Stars in our own Milky Way Galaxy are scattered through this eye-catching field of view. From the early hours after midnight on August 13, the 30 second exposure of the night sky over Busko-Zdroj, Poland records the colorful and bright trail of a Perseid meteor. Seen near the peak of the annual Perseid meteor shower it flashes from lower left to upper right. The hurtling grain of cosmic sand, a piece of dust from periodic comet Swift-Tuttle, vaporized as it passed through planet Earth’s atmosphere at almost 60 kilometers per second. Just above and right of center, well beyond the stars of the Milky Way, lies the island universe known as M31 or…

英仙座流星雨和失落的流星

英仙座流星雨和失落的流星

ByNASA中文

2021年8月9日 Perseus and the Lost Meteors Image Credit & Copyright: Tomas Slovinsky (Slovakia) & Petr Horalek (Czech Republic; Institute of Physics in Opava) Explanation: What’s the best way to watch a meteor shower? This question might come up later this week when the annual Perseid Meteor Shower peaks. One thing that is helpful is a dark sky, as demonstrated in the featured composite image of last year’s Perseids. Many more faint meteors are visible on the left image, taken through a very dark sky in Slovakia, than on the right image, taken through a moderately dark sky in the Czech Republic. The band of the Milky Way Galaxy bridges the two coordinated images, while the meteor shower radiant in the constellation of Perseus is clearly…

火流星的光与声

火流星的光与声

ByNASA中文

2021年03月15日 Meteor Fireballs in Light and Sound Image Credit & Copyright: Thomas Ashcraft (Radio Fireball Observatory) Explanation: Yes, but have you ever heard a meteor? Usually, meteors are too far away to make any audible sound. However, a meteor will briefly create an ionization trail that can reflect a distant radio signal. If the geometry is right, you may momentarily hear — through your radio — a distant radio station even over static. In the featured video, the sounds of distant radio transmitters were caught reflecting from large meteor trails by a sensitive radio receiver — at the same time the bright streaks were captured by an all-sky video camera. In the video, the bright paths taken by four fireballs across the sky near Lamy,…

色彩缤纷的四分仪流星

色彩缤纷的四分仪流星

ByNASA中文

2021年02月02日 A Colorful Quadrantid Meteor Image Credit & Copyright: Frank Kuszaj Explanation: Meteors can be colorful. While the human eye usually cannot discern many colors, cameras often can. Pictured is a Quadrantids meteor captured by camera over Missouri, USA, early this month that was not only impressively bright, but colorful. The radiant grit, likely cast off by asteroid 2003 EH1, blazed a path across Earth’s atmosphere. Colors in meteors usually originate from ionized elements released as the meteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and nickel glowing green. Red, however, typically originates from energized nitrogen and oxygen in the Earth’s atmosphere. This bright meteoric fireball was gone in a flash — less than a second — but it left a wind-blown…

远方的小行星

远方的小行星

ByNASA中文

2021年01月31日 Asteroids in the Distance Image Credit: NASA, ESA, Hubble; R. Evans & K. Stapelfeldt (JPL) Explanation: Rocks from space hit Earth every day. The larger the rock, though, the less often Earth is struck. Many kilograms of space dust pitter to Earth daily. Larger bits appear initially as a bright meteor. Baseball-sized rocks and ice-balls streak through our atmosphere daily, most evaporating quickly to nothing. Significant threats do exist for rocks near 100 meters in diameter, which strike the Earth roughly every 1000 years. An object this size could cause significant tsunamis were it to strike an ocean, potentially devastating even distant shores. A collision with a massive asteroid, over 1 km across, is more rare, occurring typically millions of years apart, but could…

承载龙宫小行星的样品舱返回地球

承载龙宫小行星的样品舱返回地球

ByNASA中文

2020年12月14日 Capsule Returns from Asteroid Ryugu Video Credit: JAXA, Hayabusa2 Explanation: The streak across the sky is a capsule returning from an asteroid. It returned earlier this month from the near-Earth asteroid 162173 Ryugu carrying small rocks and dust from its surface. The canister was released by its mothership, Japan’s Hayabusa2, a mission that visited Ryugu in 2018, harvested a surface sample in 2019, and zoomed back past Earth. The jettisoned return capsule deployed a parachute and landed in rural Australia. A similar mission, NASA’s OSIRIS- REx, recently captured rocks and dust from a similar asteroid, Bennu, and is scheduled to return its surface sample to Earth in 2023. Analyses of compounds from these asteroids holds promise to give humanity new insights about the early…

玉龙雪山上空的火星和流星

玉龙雪山上空的火星和流星

ByNASA中文

2020年11月21日 Mars and Meteor over Jade Dragon Snow Mountain Image Credit & Copyright: Jeff Dai (TWAN) Explanation: A brilliant yellowish celestial beacon, Mars still dazzles in the night. Peering between clouds the wandering planet was briefly joined by the flash of a meteor in this moonless dark sky on November 18. The single exposure was taken as the Earth swept up dust from periodic comet Tempel-Tuttle during the annual Leonid Meteor Shower. The view of a rugged western horizon looks along the Yulong mountain range in Yunnan province, southwestern China. Yulong (Jade Dragon) Snow Mountain lies below the clouds and beyond the end of the meteor streak. Tomorrow’s picture: dark marking on the sky 玉龙雪山上空的火星和流星 影像提供与版权: Jeff Dai（戴建峰） (TWAN) 说明: 明亮泛黄的火星，仍然是夜空很炫目的天体，而在11月18日这个无月的夜晚，云隙后方的火星有转瞬即逝的流星为伴。拍摄这张单曝光影像之时，在每年一度的狮子座流星雨期间，地球正好穿过坦普─塔托彗星遗留的尘埃。影像里嵯峨的西方地平线，为中国西南隅云南省的玉龙山脉之绵延雪峰。在云层下方，流星痕直指的山头即为玉龙雪山。 明日的图片: dark marking on…

英仙座流星

英仙座流星

ByNASA中文

2020年8月10日 Perseids from Perseus Image Credit & Copyright: Petr Horálek Explanation: Where are all these meteors coming from? In terms of direction on the sky, the pointed answer is the constellation of Perseus. That is why the meteor shower that peaks tomorrow night is known as the Perseids — the meteors all appear to came from a radiant toward Perseus. In terms of parent body, though, the sand-sized debris that makes up the Perseids meteors come from Comet Swift-Tuttle. The comet follows a well-defined orbit around our Sun, and the part of the orbit that approaches Earth is superposed in front of the Perseus. Therefore, when Earth crosses this orbit, the radiant point of falling debris appears in Perseus. Featured here, a composite image taken…