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Glossary term: 巨蟹座

Description: 巨蟹座是黃道帶上的一個星座,也就是說,組成這個星座的恆星位於與黃道(由地球繞太陽運行的軌跡所確定的平面)相交的那部分天空。因此,從地球上看,我們會發現太陽和行星經常落在巨蟹座中。就太陽而言,這發生在每年7月下旬到8月上旬(當然,那時我們看不到巨蟹座中的恆星)。兩千年前,每年北半球夏至時,直射北迴歸線的太陽位於巨蟹座,這便是北迴歸線在英文中被稱為“巨蟹座回歸線”的緣由。但由於歲差的關係,如今每年北半球夏至時太陽不再位於巨蟹座。巨蟹座是國際天文學聯合會定義的88個現代星座之一,但其歷史可以追溯到更久遠的年代——它是公元2世紀的天文學家克羅狄斯·托勒密(Claudius Ptolemy)命名的48個星座之一。

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Term and definition status: The original definition of this term in English have been approved by a research astronomer and a teacher
The translation of this term and its definition is still awaiting approval

This is an automated transliteration of the simplified Chinese translation of this term

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

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道路上空的銀河曲線。照片左下方,兩顆明亮的恆星連成一條線,指向一個風箏狀的星群。

夜空中最亮的星

Caption: 2022年國際天文學聯合會(IAU)OAE天文攝影比賽靜態天體圖案類別榮譽獎作品。 這張照片於2016年3 月在印度尼西亞爪哇島的婆羅摩騰格塞梅魯國家公園拍攝,展現了銀河形成的拱橋和許多突出的星座,包括了夜空中最顯著的亮星。 在照片左下角,我們可以看到南門二和馬腹一,前者較低,後者較高,都位於的巨大的半人馬座中。可由它們的指引找到南十字座,南十字座的長軸指向南天極,而南天極大致位於地平線上,這是因為爪哇島幾乎位於赤道上。南十字座幾乎完全被雲層遮擋,照片中只能看到四顆明亮的星星。而南船座中的恆星組成的贗十字星群,在稍遠處的銀河上方也明顯可見,容易使人混淆。 真正的南十字座和贗十字星群之間的粉紅色斑點是船底座星雲,距離地球約8500光年,位於船底座,肉眼看不到。在船底座,我們還可以看到夜空中第二亮的恆星——老人星,它就在銀河和地面道路之間。 更亮的是天狼星,夜空中最亮的恆星。天狼星位於大犬座,大犬座是獵戶座的兩隻獵犬之一。獵戶座在照片的右半部分,地平線附近雲層的上方。獵戶座的腰帶上有三顆明亮的恆星,其連線左上指向天狼星,右下指向堪堪露出地平線的畢宿五。 獵戶座包含了天空中最亮的幾顆恆星,是色彩最豐富的星座,因為它擁有參宿七——銀河下方靠右的一顆藍色亮星,以及參宿四——參宿七右上方較高位置的一顆紅色亮星。在它們之間,三顆恆星組成了著名的星群——獵戶座腰帶。獵戶座大星雲就在獵戶座腰帶旁邊,這是一個恆星形成區,其明亮的中心即便用肉眼看也清晰可見,在這張照片中也是如此清晰。 在參宿四的上方,銀河的另一側,可以看到明亮的南河三,其英文名稱Procyon的字面意思是”在狗之前“。在希臘神話中,它被看作由單顆恆星組成的星群,是與獵戶座相伴的小獵犬,後來演變成了現代的小犬座。 在照片右上角,巨蟹座的蜂巢星團很容易辨認。在其下方,可以看到雙子座的北河二和北河三,它們在這張照片中並不顯眼。與之形成鮮明對比的是,御夫座的明亮白色恆星五車二,在照片右邊緣中部的雲層中閃閃發光。 在地面道路周圍可以看到一些光汙染。
Credit: Giorgia Hofer/IAU OAE

License: CC-BY-4.0 Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons

Related Diagrams


Cancer appears as an inverted “Y” on the sky, with its vertex almost exactly on the ecliptic which runs ESE to WNW

Cancer Constellation Map

Caption: The zodiac constellation Cancer and its surrounding constellations. Starting from the top of the diagram and going clockwise, these are Lynx, Gemini, Canis Minor, Hydra, Leo and Leo Minor. The ecliptic (shown here as a blue line) passes almost exactly through the middle of the constellation, this is the path the Sun appears to take across the sky over the course of a year. The Sun is in Cancer from late July to mid August. The other planets of the Solar System can often be found in Cancer. Cancer lies just north of the celestial equator and is thus visible at some time in the year from all of planet Earth except for the most antarctic regions of the world. Cancer is most visible in the evenings in the northern hemisphere spring and southern hemisphere autumn. Two star clusters are visible in Cancer: M44, an open cluster often called the Beehive Cluster, and M46, a denser open cluster with about four times more stars than M44. These clusters are indicated by yellow circles with a dotted border on the map. The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labelled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the line marking the ecliptic, nor the lines joining the stars appear on the sky.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by IAU/Sky & Telescope

License: CC-BY-4.0 Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons


Leo resembles a lion standing on the ecliptic (which runs ESE to WNW) with its nose pointed northwest.

Leo Constellation Map

Caption: The zodiac constellation Leo and its surrounding constellations. Starting from the top of the diagram and going clockwise, these are Leo Minor, Cancer, Sextans, Hydra, Crater, Virgo and Ursa Major. The brightest star in Leo, Regulus, lies almost exactly on the ecliptic (shown here as a blue line): the path the Sun appears to take across the sky over the course of a year. The Sun spends the period from mid August to mid September in Leo. The other planets in the Solar System can often be found in Leo. Leo spans the celestial equator and is thus part of it is visible at some time in the year from all of planet Earth with some of the constellation obscured for the most arctic and antarctic regions of the world. Leo is most visible in the evenings in the northern hemisphere spring and southern hemisphere autumn. Several objects can be seen in Leo, including M65 and M66 – two galaxies in the Leo Triplet, a trio of galaxies including NGC 3628, not listed here. In addition, M96, a spiral galaxy, can be seen as a fuzzy object using a small telescope, and Messier 105, an elliptical galaxy. Each of these objects are labelled on the map as red ellipses. The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labelled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the line marking the ecliptic, nor the lines joining the stars appear on the sky.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by IAU/Sky & Telescope

License: CC-BY-4.0 Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons


Hydra is shaped like a snake going from the south east to the north west

Hydra Constellation Map

Caption: The constellation Hydra with its bright stars and surrounding constellations. Hydra is surrounded by (going clockwise from the top): Leo, Cancer, Canis Minor, Monoceros, Puppis, Pyxis, Antlia, Centaurus, Lupus, Libra, Virgo, Corvus, Crater and Sextans. Hydra is a large constellation that covers over a quarter of the celestial sphere in right ascension. It also spans the celestial equator and thus part of the constellation is visible from everywhere on the Earth at some point in the year. All parts of the constellation are visible at some point for all but the most antarctic parts of the southern hemisphere and to equatorial and most temperate regions of the northern hemisphere. However the wide span of the constellation means that all of it may not be visible at the same time in many of these regions. Hydra is best viewed in the northern hemisphere spring and southern hemisphere autumn. The famous spiral galaxy M83, also known as the Pinwheel Galaxy, lies in Hydra. It is marked here with a red ellipse. The planetary nebula NGC 3242 can also be found in Hydra. It is marked here with a green circle with a plus sign superimposed on it. The open cluster M48 is marked here with a yellow circle while the globular cluster M68 is marked with a yellow circle with a plus sign superimposed on it. The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. The blue line on the diagram marks the ecliptic. Neither the constellation boundaries, nor the line marking the ecliptic, nor the lines joining the stars appear on the sky.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope

License: CC-BY-4.0 Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons


Lynx appears as an uneven line going from the south east to the north west

Lynx Constellation Map

Caption: Lynx is a northern constellation and thus the whole constellation is visible at some point in the year throughout the northern hemisphere. The whole constellation is also visible in equatorial regions of the southern hemisphere with parts of the constellation visible in southern temperate regions. Lynx is best viewed in the evenings in the northern hemisphere winter and southern hemisphere summer. The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. The blue line at the bottom right of the diagram marks the ecliptic. Neither the constellation boundaries, nor the line marking the ecliptic, nor the lines joining the stars appear on the sky.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope

License: CC-BY-4.0 Creative Commons 姓名標示 4.0 國際 (CC BY 4.0) icons