Caption: 國際天文學聯合會 OAE 天文攝影比賽星軌類第二名。 天文學即使不是最古老的科學，也是其中之一，因此千百年來與各種文化都有著千絲萬縷的聯繫。這張圖片以巨石陣為背景，在某種程度上傳達了這種聯繫。關於天文學家所說的考古天文學遺址，以及它們與天空的聯繫（如季節、月相等），有很多研究。古今中外的文明對天空中的景象都有自己的看法和解釋，這不僅與文化有關，也與人們的日常活動和季節活動有關。通常被稱為 "星軌 "的 "同心圓 "是天空視運動的結果，實際上是地球自轉的結果。圖像中心上方出現的小點是Polaris--北極星。只有北半球的觀測者才能看到北極星。北極星的高度可以用來推斷觀測者的實際緯度。巨石陣位於北緯 51°左右。這張照片攝於世界上最著名的古代遺址之一，它把我們帶回了過去，讓我們對千年前生活在那裡的人們所講述的故事產生了好奇。
Credit: Till Credner/IAU OAE

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

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

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

Caption: 這段延時攝影記錄了2020年7月拍攝的三幀畫面中標誌性的北斗七星的軌跡。影像在意大利的三個地點拍攝：拉瓦雷多三峰（Tre Cime di Lavaredo）奧隆佐迪卡多雷、裡特山（Monte Rite）奇比亞納迪卡多雷，以及拉佐牧場（Casera Razzo）維戈迪卡多雷。這場視覺奧德賽展示了北斗七星的迷人軌跡，並在夜空中繪製出天體畫卷。它不僅描繪了這個著名星群的軌跡，還捕捉到2020年7月照亮天空的罕見新智彗星 C/2020 F3 這一非凡的天文事件，為我們的夜空增添了光彩。
Credit: 喬爾賈·霍弗/國際天文學聯合會教育辦公室 (CC BY 4.0)

Caption: 北斗七星優雅地移動於加利福尼亞州莫諾湖超凡脫俗的凝灰岩層之上。延時攝影捕捉了北斗七星穿過北方地平線直至下合的過程。在莫諾湖的緯度（+38°）上，北斗七星的星星幾乎都是環極星，除了阿爾凱德（Alkaid）。北極星位於地平線之上38°的位置，正好在視野的右上角之外。月光將大地籠罩在柔和的光暈中，隨著月亮落下，光暈逐漸變暗，整個場景陷入黑暗之中。
Credit: Fabrizio Melandri/IAU OAE (CC BY 4.0)

Caption: 2022 年 3 月拍攝的這張照片中，北京故宮矗立在星軌編織的夜空芭蕾之下，見證著古老的天體之間的聯繫。紫禁城在設計時考慮到了宇宙的排列，呼應了北極星的方位，北極星又叫 Polaris，是長期以來指引航海者的天體之錨，象徵著天空的穩定。人們相信皇帝是北極星在人間的化身，是連接天地的橋梁。在這張用智能手機拍攝的和諧的一小時曝光照片中，星星的軌跡描繪了它們夜間穿越蒼穹的旅程，它們向北極星匯聚，體現了建築設計和天體軌跡的精確性。
Credit: Stephanie Ziyi Ye/IAU OAE (CC BY 4.0)

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

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

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

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

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

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

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

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

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

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

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

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