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Glossary term: 拱极星

Description: 在地球上的大多数地方,都能在地平线以上一定距离的天空中看到北天极或南天极。对于处于这样一个位置的观测者来说,随着时间的流逝,星星似乎在围绕着天极旋转:每颗恒星都在天空中划出一个圆圈,其中心是地轴指向的天极。在圆圈与观测者地平线相交的两点,即东点和西点,该恒星将分别升起和落下。对于距离天极足够近的恒星,其划出的圆圈将完全位于地平线之上。我们的观测者将永远看不到这些恒星升起或落下。这些永不落下的恒星被称为拱极星。

哪些恒星是拱极星取决于观测者的地理纬度和恒星的赤纬——后者是恒星所在位置与天赤道之间的夹角。在北半球,如果一颗恒星的赤纬大于90°减去观测者的地理纬度,那么它就是拱极星。在南半球,我们需要考虑到地理南纬和恒星的南赤纬都带有负号。考虑到这些负号,在南半球,如果一颗恒星的赤纬小于-90°减去观测者的地理纬度,那么它就是拱极星。

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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

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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全景天空图像。在一圈形状像门框的石头上方,明亮弯曲的星轨似乎形成了圆圈

石阵与星环,巨石阵上方的星轨,作者:Till Credner,德国

Caption: 国际天文学联合会 OAE 天文摄影比赛星轨类第二名。 天文学即使不是最古老的科学,也是其中之一,因此千百年来与各种文化都有着千丝万缕的联系。这张图片以巨石阵为背景,在某种程度上传达了这种联系。关于天文学家所说的考古天文学遗址,以及它们与天空的联系(如季节、月相等),有很多研究。古今中外的文明对天空中的景象都有自己的看法和解释,这不仅与文化有关,也与人们的日常活动和季节活动有关。通常被称为 "星轨 "的 "同心圆 "是天空视运动的结果,实际上是地球自转的结果。图像中心上方出现的小点是Polaris--北极星。只有北半球的观测者才能看到北极星。北极星的高度可以用来推断观测者的实际纬度。巨石阵位于北纬 51°左右。这张照片摄于世界上最著名的古代遗址之一,它把我们带回了过去,让我们对千年前生活在那里的人们所讲述的故事产生了好奇。
Credit: Till Credner/IAU OAE

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Bright star trails for arcs around the center of the image behind the silhouette of a tree

Half day exposure to the north star, by Fabrizio Melandri, Italy

Caption: First place in the IAU OAE Astrophotography Contest, category Star trails. This star trail image shows the apparent movement of the stars in the night sky, which results from the Earth’s rotation around its polar axis. The trees in the foreground serve as an anchor as we turn with the Earth. The bright white semi-circle in the center of the image is the North (Pole) star – Polaris, which is located very close to the North Celestial Pole. One way to imagine that the Earth is at center of hollow crystal sphere, and the stars are embedded on this sphere, as the Earth spins on its axis, an observer on Earth sees the stars rising and setting, following an arc, because the horizon prevents the observer from the full arc for stars that are further away from the Celestial Pole. The North Celestial Pole (and its opposite the South Celestial Pole) is essentially formed by extending the line of the Earth’s axis. Capturing this image requires the photographer to take a long exposure with the camera on a tripod and pointing towards the Pole Star (North Hemisphere). In the Southern Hemisphere there is no star as close as Polaris is to the Celestial Pole, so the position of the South Celestial Pole is found using the South Cross and Pointer Stars (Alpha and Beta Centauri). Although overall the image has a slight blue tint, it does capture the varying colours of stars, it is easy to distinguish between the higher temperature blue stars and the lower temperature of the whitish stars, and even lower temperature reddish stars. The reason for this variation in colour is because higher temperature stars emit more in shorter wavelengths (bluer), compared to lower temperature stars which emit in longer wavelengths (redder).
Credit: Fabrizio Melandri/IAU OAE

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The ladle-shaped Big Dipper with the orange star Arcturus to its left. Right is the diffuse disk-shaped Andromeda galaxy

Dreamlike Starry Sky and Airglow

Caption: Winner in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   This spectacular image shows a range of prominent constellations visible in the night sky over the desert of inner Mongolia, taken in August 2019. The yellowish star in the bottom left side is Arcturus, one of the brightest stars in the night sky, and the brightest in the constellation Boötes. The handle of the Big Dipper points towards this bright star and the Dipper is also visible above Boötes. The Northern Dipper (Bei Dou) is a traditional Chinese constellation. It is considered a chariot in which the Judges for Nobility are sitting. Arcturus is considered a single-star asterism, named the Horn, which forms part of the Chinese super-constellation for the spring, the Azure Dragon of the East. The front of the Northern Dipper points towards the star at the top of the photograph which is now called Polaris, the northern Pole Star. In ancient China, there was no bright star at the pole, so the stars in the nearest vicinity of the pole were considered to belong to the emperor and his family in the constellation the Purple Forbidden Palace. At least as early as mediaeval times, Polaris was considered part of the constellation of the Great Emperor of Heaven. Corona Borealis is also visible in the top right corner of this image, although not in its completeness. It is called the Coiled Thong in China. With its characteristic semi-circular shape, this is one of the smaller constellations of the 88 modern ones, but also can be traced back at least three or four millennia through the Roman “Crown”, the Greek wedding “Wreath”, and the Babylonian “Asterism of Dignity”. The modern name literally means “Northern Crown” in Latin. At the upper-right edge of the image, we find the part of the modern constellation Cassiopeia that is considered the Flying Corridor and an Auxiliary Road in ancient China. The W-shape of Cassiopeia is cut off by the edge of the photograph but the constellations to its south and southeast, Andromeda and Perseus, are clearly recognisable. Prominently we see the Andromeda galaxy, the most distant object that is visible to the unaided eye. It is located at the outermost outliers of the band of the Milky Way, which could explain why it has not been mentioned explicitly in ancient star catalogues, as it was mistakenly thought to be part of the Milky Way. The photograph also shows clearly reddish parts of the Milky Way that don’t appear bright to the naked eye, and also open clusters that are formed from the same molecular cloud, i.e., groups of stars with similar ages. This region is part of many big and small asterisms in traditional Chinese uranology.
Credit: Likai Lin/IAU OAE

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The Big Dipper, seven bright stars shaped like a ladle, viewed in 4 seasons, each time at a different angle

Big Dipper in Four Seasons

Caption: Winner in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   As Earth moves around the Sun, the positions of the stars in the night sky appear to change over the course of the year. This is well exemplified in this mosaic, with images taken in all four seasons throughout 2020 in the region of Veneto, Italy, showing the apparent motion of the Ursa Minor and Ursa Major constellations. Ursa Minor, the Little Bear, is a constellation of the northern hemisphere, and it contains the northern celestial pole, in our current epoch marked by a bright star called Polaris or the Pole Star. For centuries Polaris has been used for navigation in the northern hemisphere, as it has been almost at the exact pole position for roughly 200 years. In the Middle Ages and antiquity, there was no pole star; the celestial north pole lay in a dark region and the Greeks considered the “Little She-Bear” as a companion of the “Great She-Bear”, which is more easily recognizable. The brightest stars of these constellations were alternatively also considered as chariots by the Greeks, as written in Aratus’s famous didactic poem from the 3rd century before the common era. The most famous asterism in Ursa Major, composed of seven stars, has different names across the (northern) world. While considered as a chariot by the Greeks, it is “The Northern Dipper” in China, and “The Seven Oxen” for the ancient Romans. It was also the navigational purpose that led to the name The Great She-Bear, Ursa Major; for the Greeks, travelling towards the direction of the horizon above which Ursa Major appears meant moving towards the land of the bears (northern Europe). An animal is clearly recognizable when taking into account all the fainter stars in the vicinity of the seven bright ones. They considered it a female bear because Greek mythology connects this animal with the nymph Callisto, whose story describes the initiation rituals for women. In the top left, we see an image taken on a spring evening, while the image below shows the same portion of the sky on a summer evening. Going counterclockwise, we see the sky during autumn in the bottom right image, while the top right finally shows this portion of the sky in the winter. Note that the relative positions of Ursa Minor and the Big Dipper don’t change, but all stars appear to be moved in a circle around Polaris. This star pointing due north lies at the point where Earth’s rotational axis intersects the celestial sphere. The shift of constellations throughout the year is therefore a globe-clock or a globe-calendar, used by ancient civilizations to measure the year, and to predict the changes of seasons. It helps to establish, for instance, the best time for sowing and sailing as winds change with the seasons.
Credit: Giorgia Hofer/IAU OAE

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北斗七星逐渐向左侧地平线下方移动,而右侧则有一颗彗星在天空中升起。

北斗七星和新智彗星 C2020 F3

Caption: 这段延时摄影记录了2020年7月拍摄的三帧画面中标志性的北斗七星的轨迹。影像在意大利的三个地点拍摄:拉瓦雷多三峰(Tre Cime di Lavaredo)奥隆佐迪卡多雷、里特山(Monte Rite)奇比亚纳迪卡多雷,以及拉佐牧场(Casera Razzo)维戈迪卡多雷。这场视觉奥德赛展示了北斗七星的迷人轨迹,并在夜空中绘制出天体画卷。它不仅描绘了这个著名星群的轨迹,还捕捉到2020年7月照亮天空的罕见新智彗星 C/2020 F3 这一非凡的天文事件,为我们的夜空增添了光彩。
Credit: 乔尔贾·霍弗/国际天文学联合会教育办公室 (CC BY 4.0)

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北斗七星在天空中下沉,其柄部扫过的圆圈比星群的碗部更大。

莫诺湖上空的北斗七星

Caption: 北斗七星优雅地移动于加利福尼亚州莫诺湖超凡脱俗的凝灰岩层之上。延时摄影捕捉了北斗七星穿过北方地平线直至下合的过程。在莫诺湖的纬度(+38°)上,北斗七星的星星几乎都是环极星,除了阿尔凯德(Alkaid)。北极星位于地平线之上38°的位置,正好在视野的右上角之外。月光将大地笼罩在柔和的光晕中,随着月亮落下,光晕逐渐变暗,整个场景陷入黑暗之中。
Credit: Fabrizio Melandri/IAU OAE (CC BY 4.0)

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一座传统的中国建筑。上方的星星围绕北极星形成一个圆形图案。

故宫星轨

Caption: 2022 年 3 月拍摄的这张照片中,北京故宫矗立在星轨编织的夜空芭蕾之下,见证着古老的天体之间的联系。紫禁城在设计时考虑到了宇宙的排列,呼应了北极星的方位,北极星又叫 Polaris,是长期以来指引航海者的天体之锚,象征着天空的稳定。人们相信皇帝是北极星在人间的化身,是连接天地的桥梁。在这张用智能手机拍摄的和谐的一小时曝光照片中,星星的轨迹描绘了它们夜间穿越苍穹的旅程,它们向北极星汇聚,体现了建筑设计和天体轨迹的精确性。
Credit: Stephanie Ziyi Ye/IAU OAE (CC BY 4.0)

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Related Diagrams


Cassiopeia appears as a double-u shape tilted up at the left end by about 45 degrees

Cassiopeia Constellation Map

Caption: The constellation Cassiopeia along with its bright stars and its surrounding constellations. Cassiopeia is surrounded by (going clockwise from the top):Cepheus, Andromeda, Perseus and Camelopardalis. Cassiopeia is a northern constellation that is visible from all of the northern hemisphere and equatorial regions of the southern hemisphere. It is most visible in the evenings in the northern hemisphere late autumn and southern hemisphere late spring. The open star clusters M52, M103, NGC 457 and NGC 663 all lie in this constellation. These are marked with yellow circles. Two dwarf elliptical galaxies NGC 147 and NGC 185 lie in the southern part of the constellation. These are marked with red ellipses and are gravitationally bound to the larger Andromeda galaxy which lies to the south in the constellation of Andromeda. 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. Neither the constellation boundaries, 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

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Ursa Minor appears as a small ladle with the end of the handle, the location of Polaris, at the north pole

Ursa Minor Constellation Map

Caption: The constellation Ursa Minor along with its bright stars and its surrounding constellations. Ursa Minor is surrounded by (going clockwise from the top): Cephus, Camelopardalis and Draco. Ursa Minor is notable as its brightest star, Polaris is the northern pole star. Ursa Minor is visible from the entire northern hemisphere with some parts of the constellation being visible from equatorial regions of the southern hemisphere. It is also circumpolar for temperate and arctic regions of the northern hemisphere. Polaris, lying very close the north celestial pole is circumpolar for the whole of the northern hemisphere. The constellation is most visible in the evenings in the northern hemisphere summer and southern hemisphere winter. This diagram maps an area around the north celestial pole. Here lines of constant right ascension converge. The right ascension values (in hours) of these lines are marked on the x-axis above and below the diagram. Some of the lines of constant declination (in degrees) are marked on the y-axis. 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. Neither the constellation boundaries, 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

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Ursa Major appears as a ladle with the handle to the east & the cup to the west. Lines of fainter stars extend to the south

Ursa Major Constellation Map

Caption: The constellation Ursa Major along with its bright stars and its surrounding constellations. Ursa Major is surrounded by (going clockwise from the top): Draco, Camelopardalis, Lynx, Leo Minor, Leo, Coma Berenices, Canes Venatici and Boötes. Ursa Major is famous for the prominent asterism often known in English as the Big Dipper or the Plough. This prominent northern asterism has a wide variety of names from cultures across the world. While most constellations and asterisms are made up of unrelated stars that randomly appear close together on the sky, five of the stars in the Big Dipper are part of the Ursa Major Moving Group, a group of stars moving through space together that likely formed in the same location 300 million years ago. The two stars on the right-hand end of the Big Dipper on this diagram form a pair of pointer stars that can be used to locate Polaris, the northern pole star which lies in the constellation of Ursa Minor. Ursa Major is a northern constellation and is visible from northern and equatorial regions. Parts of the constellation are visible from all but the most antarctic parts of the southern hemisphere but not all temperate regions of the southern hemisphere can see all of the Big Dipper. Conversely the Big Dipper and much of the rest of the constellation are circumpolar in arctic and many temperate regions of the northern hemisphere. Ursa Major is most visible in the evening in the northern hemisphere spring and southern hemisphere autumn. Two prominent galaxies appear in the northern part of this constellation, the spiral galaxy M81 and M82, a possible spiral galaxy whose structure is difficult to observe from the Earth as it appears edge-on. Both are shown here as red ellipses. The planetary nebula M97 (the Owl Nebula) lies in the middle of the constellation and is marked by a green circle superimposed on a plus symbol. 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. Neither the constellation boundaries, 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

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Apus has an northward-pointing isosceles triangle on the east end of an east-west line.

Apus Constellation Map

Caption: The constellation Apus with its bright stars and surrounding constellations. Apus is surrounded by (going clockwise from the top): Triangulum Australe, Circinus, Musca, Chamaeleon, Octans, Pavo and Ara. Apus is a southern constellation lying close to the south celestial pole. As such it is visible at some point in the year from the entire southern hemisphere but is only visible from the most equatorial regions of the northern hemisphere. Apus is circumpolar for all temperate and antarctic regions of the southern hemisphere. It is most visible in the evenings in the northern hemisphere summer and southern hemisphere autumn. The globular cluster NGC 6101 can be found in Apus. It is marked here with a yellow circle with a plus symbol superimposed on it. This diagram maps an area around the south celestial pole. Here lines of constant right ascension converge. The right ascension values (in hours) of these lines are marked on the x-axis above and below the diagram. Lines of constant declination (in degrees) are marked on the y-axis. 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. Neither the constellation boundaries, 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

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Auriga looks like a head with a pointed hat on. The ecliptic runs East to West below Auriga

Auriga Constellation Map

Caption: The constellation Auriga with its bright stars and surrounding constellations. Auriga is surrounded by (going clockwise from the top): Camelopardalis, Perseus, Taurus, Gemini and Lynx. Capella, the brightest star in Auriga, is the sixth brightest star in the night sky. As a northern constellation, Auriga is visible from the whole of the northern hemisphere at some point in the year. The whole of the constellation is visible to equatorial regions of the southern hemisphere with parts of it visible to temperate southern regions. The whole constellation is circumpolar from arctic regions. The constellation is best viewed in the evening in the late northern hemisphere winter and late southern hemisphere summer. Auriga lies in the plane of the Milky Way and thus hosts a number of open clusters. Of these M36, M37 and M38 are marked on this diagram with yellow circles. IC 405, also known as the flaming star nebula, is marked here with a green square. 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. Neither the constellation boundaries, nor the lines joining the stars appear on the sky. The blue line at the bottom of the diagram marks the ecliptic.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope

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Camelopardalis has no very bright stars and no well-defined shape

Camelopardalis Constellation Map

Caption: The constellation Camelopardalis with its bright stars and surrounding constellations. Camelopardalis is surrounded by (going clockwise from the top): Cepheus, Cassiopea, Perseus, Auriga, Lynx, Ursa Major, Draco and Ursa Minor. Camelopardalis is a large constellation but contains relatively few bright stars. Camelopardalis is a northern constellation and as such the whole constellation is visible for the whole northern hemisphere at some point in the year. It is also visible from equatorial parts of the southern hemisphere with some parts visible to temperate southern regions. The whole constellation is circumpolar for all arctic and more northerly temperate regions of the northern hemisphere. Camelopardalis is best viewed in the evening in the late northern hemisphere winter and late southern hemisphere summer. The spiral galaxies NGC 2403 and IC 342 lie in Camelopardalis and are marked here with red ellipses. This diagram maps an area around the north celestial pole. Here lines of constant right ascension converge. The right ascension values of these lines are marked on the x-axis above and below the diagram. Some of the lines of constant declination are marked on the y-axis. 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. Neither the constellation boundaries, 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

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Cepheus appears as a head wearing a pointy hat tilted anticlockwise by 45 degrees

Cepheus Constellation Map

Caption: The constellation Cepheus along with its bright stars and surrounding constellations. Cepheus is surrounded by (going clockwise from the top): Camelopardalis, Ursa Minor, Draco, Cygnus, Lacerta and Cassiopeia. Cepheus is a large constellation. Its most notable star is Delta Cephei, the prototype for the class of variable stars known as Cepheid variables. These are variable stars which can be used to estimate distances both within our galaxy and to nearby galaxies. Cepheus lies close to the north celestial pole. As such it is circumpolar for arctic and temperate regions of the northern hemisphere. The whole of the constellation is also visible at some point in the year in equatorial regions of the northern hemisphere with parts of it visible in equatorial regions of the southern hemisphere. It is best viewed in the evening in the northern hemisphere late autumn and southern hemisphere late spring. The open cluster NGC 188 lies in Cepheus and is marked here with a yellow circle. The nebula NGC 7023 also lies in the constellation and is marked with a green square. The red ellipse in the lower right marks the position of the spiral galaxy NGC 6946. This diagram maps an area around the north celestial pole. Here lines of constant right ascension converge. The right ascension values of these lines are marked on the x-axis above and below the diagram. Some of the lines of constant declination are marked on the y-axis. 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. Delta Cephei is marked with a circle around a dot as it is a variable star. Mu Cephei is also a variable star marked here as an open circle. 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. Neither the constellation boundaries, 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

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Chamaeleon appears as flat rectangle orientated East-West with a line extending to the West (the right here)

Chamaeleon Constellation Map

Caption: The constellation Chamaeleon with its bright stars and surrounding constellations. Chamaeleon is surrounded by (going clockwise from the top): Carina, Volans, Mensa, Octans, Apus and Musca. Chamaeleon lies close to the south celestial pole and this the whole of the constellation is visible from the whole southern hemisphere at some point in the year. All or part of the constellation can be seen from equatorial regions of the northern hemisphere. The whole constellation is circumpolar for all but the most equatorial regions of the southern hemisphere. Chamaeleon is best viewed in the evenings in the northern hemisphere spring and southern hemisphere autumn. This diagram maps an area around the south celestial pole. Here lines of constant right ascension converge. The right ascension values of these lines are marked on the x-axis above and below the diagram. The solid circle around the pole marks a line of -80° declination with the larger, incomplete circles above it marking -70° and -60° declination respectively. 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. Neither the constellation boundaries, 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 署名 4.0 国际 (CC BY 4.0) icons


Circinus appears as a thin isosceles triangle pointing to the south-west (lower right)

Circinus Constellation Map

Caption: The constellation Circinus with its brighter stars and surrounding constellations. Circinus is surrounded by (going clockwise from the top): Lupus, Centaurus, Musca, Apus, Triangulum Australe and Norma. Circinus is a relatively small constellation with few bright stars. Circinus is a southern constellation and is thus the whole constellation is visible from the whole southern hemisphere at some point in the year. The whole constellation can also be seen from some equatorial regions of the northern hemisphere with parts of the constellation visible from the remaining equatorial regions and some northern hemisphere temperate locations. The constellation is circumpolar for all antarctic and some southern hemisphere temperate regions. Circinus is best viewed in the evening in the northern hemisphere summer and southern hemisphere winter. The open cluster NGC 5823 lies in Circinus and is marked here with a yellow circle. 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. Neither the constellation boundaries, 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 署名 4.0 国际 (CC BY 4.0) icons


The stars in Dorado form a rough line from south-east to north-west. The LMC lies on the southern boundary of Dorado

Dorado Constellation Map

Caption: The constellation Dorado with its bright stars and surrounding constellations. Dorado is surrounded by (going clockwise from the top): Pictor, Caelum, Horologium, Reticulum, Hydrus, Mensa and Volans. Dorado is a southern constellation and thus the whole constellation is visible at some point in the year from the whole southern hemisphere. The whole constellation is also visible to equatorial regions of the northern hemisphere. Dorado is circumpolar for temperate and antarctic regions of the southern hemisphere. This constellation is best viewed in the northern hemisphere winter and southern hemisphere summer. The Large Magellanic Cloud (LMC), a satellite galaxy of the Milky Way, lies in Dorado and the neighboring constellation Mensa. The outline of the Large Magellanic Cloud is marked here as a roughly circular loop in green. The open cluster NGC 2070 lies at the heart of the Tarantula Nebula. This is marked here with a green square. 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. Neither the constellation boundaries, 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 署名 4.0 国际 (CC BY 4.0) icons


Draco has the shape of a backward letter s rotated by 90 degrees

Draco Constellation Map

Caption: The constellation Draco with its bright stars and surrounding constellations. Draco is surrounded by (going clockwise from the top): Cepheus, Ursa Minor, Boötes, Hercules, Lyra and Cygnus. Draco is a sprawling northern constellation, parts of which lie close to the celestial north pole. As such the whole constellation is visible at some point in the year from the whole northern hemisphere and a thin sliver of the southern hemisphere near the equator. Parts of the constellation are visible from all other southern equatorial and some southern temperate regions. Draco is best viewed in the evenings in the northern hemisphere summer and southern hemisphere winter. The planetary nebula NGC 6543 (also known as the Cat’s Eye Nebula) lies in Draco. It is marked here with a green circle superimposed on a plus sign. This diagram maps an area around the north celestial pole. Here lines of constant right ascension converge. The right ascension values of these lines are marked on the x-axis above and below the diagram. Some of the lines of constant declination are marked on the y-axis. 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. Neither the constellation boundaries, 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 署名 4.0 国际 (CC BY 4.0) icons


Horologium has the shape of a distorted backwards question mark

Horologium Constellation Map

Caption: The constellation Horologium with its bright stars and surrounding constellations. Horologium is surrounded by (going clockwise from the top): Eridanus, Hydrus, Reticulum, Dorado and Caelum. Horologium is a southern constellation and thus is visible in the whole southern hemisphere at some point in the year. The whole constellation is also visible from equatorial parts of the northern hemisphere with parts of it visible to some northern temperate regions. Horologium is circumpolar in antarctic and some temperate regions of the southern hemisphere. This constellation is best viewed in the evenings in the northern hemisphere winter and southern hemisphere summer. The globular cluster NGC 1261 lies in Horologium, it is marked here 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. Neither the constellation boundaries, 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 署名 4.0 国际 (CC BY 4.0) icons

Related Activities


Navigation in the Ancient Mediterranean and Beyond

Navigation in the Ancient Mediterranean and Beyond

astroEDU educational activity (links to astroEDU website)
Description: Learn the ancient skill of Celestial Navigation

License: CC-BY-4.0 Creative Commons 署名 4.0 国际 (CC BY 4.0) icons

Tags: History , Geography , Celestial navigation
Age Ranges: 14-16 , 16-19
Education Level: Middle School , Secondary
Areas of Learning: Discussion Groups , Modelling , Social Research
Costs: Low Cost
Duration: 1 hour 30 mins
Group Size: Group
Skills: Analysing and interpreting data , Asking questions , Communicating information , Developing and using models , Planning and carrying out investigations , Using mathematics and computational thinking