Vulpecula Constellation Map

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Caption: The constellation Vulpecula with its brighter stars and surrounding constellations. Vulpecula is surrounded by (going clockwise from the top): Cygnus, Lyra, Hercules, Sagitta, Delphinus and Pegasus. Vulpecula 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 and temperate regions of the southern hemisphere. Vulpecula is best viewed in the evening in the northern hemisphere early autumn and southern hemisphere early spring. The planetary nebula M27, commonly known as the Dumbbell Nebula lies in Vulpecula and is marked here with a green cross superimposed on a plus sign. The open cluster NGC 6885 also lies in Vulpecula 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
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Glossary Terms: Apparent Magnitude , Celestial Coordinates , Constellation , Declination , Planetary Nebula , Right Ascension (RA) , Open Cluster
Categories: Naked Eye Astronomy

License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons

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Tucana Constellation Map

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Caption: The constellation Tucana with its bright stars and surrounding constellations. Tucana is surrounded by (going clockwise from the top): Grus, Indus, Octans, Hydrus, Eridanus and Phoenix. Tucana is a southern constellation and thus the whole constellation is visible at some point in the year throughout the southern hemisphere. The whole constellation is visible to some equatorial regions of the northern hemisphere with parts of the constellation visible to the remaining northern equatorial regions. Tucana is best viewed in the northern hemisphere autumn and southern hemisphere spring. The Small Magellanic Cloud (SMC), a satellite galaxy of the Milky Way lies in Tucana with a small part spilling over into the neighbouring constellation of Hydrus. The SMC is marked here with a green loop in the south east of Tucana. The globular clusters NGC 104, also known as 47 Tucanae or 47 Tuc, and NGC 362 lie in Tucana and are marked here with yellow circles with plus signs superimposed on them. While these two clusters appear close to the SMC on the sky, they are both significantly closer than that satellite galaxy. 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
Credit Link

Glossary Terms: Apparent Magnitude , Celestial Coordinates , Constellation , Declination , Globular Cluster , Right Ascension (RA) , Small Magellanic Cloud (SMC)
Categories: Naked Eye Astronomy

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Serpens Cauda Constellation Map

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Caption: A map of part of the constellation Serpens. Serpens is unique amongst IAU constellations in that it is divided into two non-contiguous parts. The part of Serpens shown here is known as Serpens Cauda, representing the tail of the serpent. This part of Serpens is surrounded by (going clockwise from the top): Ophiuchus, Sagittarius, Scutum and Aquila. Serpens Cauda spans the celestial equator thus parts of the constellation are visible at some point in the year across the Earth. The whole constellation is visible to all but the most arctic and antarctic regions. Serpens Cauda is best viewed in the evening in the northern hemisphere summer and southern hemisphere winter. The Eagle Nebula and its associated star cluster are marked here as M16 with a yellow circle. This region was the location of the famous “pillars of creation” image taken by the Hubble Space Telescope. 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 of the diagram marks the ecliptic. Neither the constellation boundaries, nor the lines joining the stars, nor the ecliptic, appear on the sky.
Credit: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope
Credit Link

Glossary Terms: Apparent Magnitude , Celestial Coordinates , Celestial Equator , Constellation , Declination , Nebula , Right Ascension (RA) , Open Cluster , Sagittarius
Categories: Naked Eye Astronomy

License: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons

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Serpens Caput Constellation Map

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Caption: A map of part of the constellation Serpens. Serpens is unique amongst IAU constellations in that it is divided into two non-contiguous parts. The part of Serpens shown here is known as Serpens Caput, representing the head of the serpent. This part of Serpens is surrounded by (going clockwise from the top): Corona Borealis, Boötes, Virgo, Libra, Ophiuchus and Hercules. Serpens Caput spans the celestial equator thus parts of the constellation are visible at some point in the year across the Earth. The whole constellation is visible to temperate and equatorial regions of the southern hemisphere and all of the northern hemisphere except a small region around the north pole. Serpens Caput is best viewed in the evening in the northern hemisphere summer and southern hemisphere winter. The globular cluster M5 lies in Serpens Caput. 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
Credit Link

Glossary Terms: Apparent Magnitude , Celestial Coordinates , Celestial Equator , Constellation , Declination , Globular Cluster , Libra , Right Ascension (RA) , Virgo
Categories: Naked Eye Astronomy

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Annual Parallax

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Created for the OAE

Caption: Distance determination has historically been a challenge for astronomy. One of the primary ways to measure distance is to use annual parallax. The Earth orbits around the Sun over the course of a year meaning that it moves from one side of the Sun (shown here as position A) to the other side of the Sun (position B) over the course of six months. It then moves back to its original position over the remaining six months. This movement subtly changes the perspective an observer on Earth sees the night sky from. This is similar to the change in viewing perspective you may get when viewing a scene from your left eye and then your right eye. The change of viewing perspective causes nearby objects to shift in position in your vision. The annual motion of the Earth around the Sun changes the perspective of the observer enough to shift the observed positions of celestial objects. How big this effect is depends on the distance to the celestial object. Nearby stars will have bigger shifts in observed position than more distant stars. The positional shift is known as the trigonometric or annual parallax (which we will call α here) and is defined as the shift in position of a star compared to what an observer at the center of the Solar System (the Sun) would see. In this diagram we see the star viewed from perspectives six months apart (positions A and B). When observed from position A the star’s shift in position will be α while when observed at position B it will be –α. Thus the relative difference in the stars position between being observed at position A and position B will be 2α. The size of the trigonometric or annual parallax in arcseconds is approximately 1 divided by the distance in parsecs. An arcsecond (often represented by a ″ symbol) is the angular diameter a one-metre-long stick would have when viewed from 206 km away. A parsec (often abbreviated to pc) is 3.26 light years or 30.86 trillion kilometres. This is 206,265 astronomical units (the typical distance between the Earth and the Sun). No other star is closer than 1 pc to the Sun so all stars in the sky have trigonometric parallaxes less than one arcsecond. While trigonometric parallaxes have long been used to measure the distances to objects in our Solar System or nearby stars, recent advances have pushed the boundaries of these distance measures further. The Gaia satellite has pushed the boundaries of parallax measurements to over a thousand parsecs. Arrays of radio telescopes can also very accurately measure the positions of very distant objects and thus their trigonometric parallax. Note the Earth and Sun are not to scale here and the Earth’s axial tilt is not accurately represented.
Credit: Aneta Margraf/IAU OAE

Glossary Terms: Angular Diameter , Annual Parallax , Astronomical Unit , Parallax
Categories: Observational Astronomy

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