御夫AE星和火焰恒星云

御夫AE星和火焰恒星云

ByNASA中文

2023年3月1日 The Flaming Star Nebula Image Credit & Copyright: Thomas Röell Explanation: Is star AE Aurigae on fire? No. Even though AE Aurigae is named the Flaming Star and the surrounding nebula IC 405 is named the Flaming Star Nebula, and even though the nebula appears to some like a swirling flame, there is no fire. Fire, typically defined as the rapid molecular acquisition of oxygen, happens only when sufficient oxygen is present and is not important in such high-energy, low-oxygen environments such as stars. The bright star AE Aurigae occurs near the center of the Flaming Star Nebula and is so hot it glows blue, emitting light so energetic it knocks electrons away from surrounding gas. When a proton recaptures an electron, light is…

优胜美地瀑布上空的ZTF彗星

优胜美地瀑布上空的ZTF彗星

ByNASA中文

2023年2月21日 Comet ZTF over Yosemite Falls Image Credit & Copyright: Tara Mostofi Explanation: They are both falling. The water in Yosemite Falls, California, USA, is falling toward the Earth. Comet ZTF is falling toward the Sun. This double cosmic cascade was captured late last month as fading Comet C/2022 E3 (ZTF) had just passed its closest to planet Earth. The orange star just over the falls is Kochab. With the exception of a brief encounter with a black bear, the featured image was a well-planned composite of a moonlit-foreground and long-duration background exposures – all designed to reconstruct a deep version of an actual single sight. Although Comet ZTF is now fading as it glides back to the outer Solar System, its path is determined…

ZTF彗星与火星

ZTF彗星与火星

ByNASA中文

2023年2月13日 Comet ZTF and Mars Image Credit & Copyright: Donato Lioce Explanation: No, Comet ZTF is not going to hit Mars. Nicknamed the Green Comet for its bright green coma, C/2022 E3 (ZTF) did, however, pass almost in front of the much-more distant planet a few days ago, very near in time to when the featured picture was taken. The two sky icons were here captured behind a famous Earth icon — the Matterhorn, a mountain in the Italian Alps with a picturesque peak. Both the foreground and background images were taken on the same evening by the same camera and from the same location. The comet’s white dust tail is visible to the right of the green coma, while the light blue ion tail…

彗星与大、小北斗

彗星与大、小北斗

ByNASA中文

2023年2月7日 A Comet and Two Dippers Image Credit & Copyright: Petr Horalek / Institute of Physics in Opava Explanation: Can you still see the comet? Yes. Even as C/2022 E3 (ZTF) fades, there is still time to see it if you know where and when to look. Geometrically, Comet ZTF has passed its closest to both the Sun and the Earth and is now headed back to the outer Solar System. Its orbit around the Sun has it gliding across the northern sky all month, after passing near Polaris and both the Big and Little Dippers last month. Pictured, Comet ZTF was photographed between the two dippers in late January while sporting an ion tail that extended over 10 degrees. Now below naked-eye visibility, Comet…

ZTF彗星的三重景观

ZTF彗星的三重景观

ByNASA中文

2023年1月31日 A Triple View of Comet ZTF Image Credit & Copyright: Javier Caldera & Miguel Gracia Explanation: Comet ZTF has a distinctive shape. The now bright comet visiting the inner Solar System has been showing not only a common dust tail, ion tail, and green gas coma, but also an uncommonly distinctive antitail. The antitail does not actually lead the comet — it is just that the head of the comet is seen superposed on part of the fanned-out and trailing dust tail. The giant dirty snowball that is Comet C/2022 E3 (ZTF) has now passed its closest to the Sun and tomorrow will pass its closest to the Earth. The main panel of the featured triple image shows how Comet ZTF looked last week…

ZTF彗星的彗尾

ZTF彗星的彗尾

ByNASA中文

2023年1月9日 Tails of Comet ZTF Image Credit & Copyright: Jose Francisco Hernández Explanation: Comet ZTF may become visible to the unaided eye. Discovered early last year, this massive snowball has been brightening as it approaches the Sun and the Earth. C/2022 E3 (ZTF) will be closest to the Sun later this week, at which time it may become visible even without binoculars to northern observers with a clear and dark sky. As they near the Sun, comet brightnesses are notoriously hard to predict, though. In the featured image taken last week in front of a picturesque star field, three blue ion tails extend to the upper right, likely the result of a variable solar wind on ions ejected by the icy comet nucleus. The comet’s…