黑体辐射

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图注： 不同温度黑体的辐射曲线。x 轴表示波长，y 轴表示黑体表面每平方米在每个波长下每秒发射的能量。 温度越高的物体，波长越短，发出的最大能量光也越蓝。尽管图中最冷的天体发出的红光达到峰值，但其他较热的天体发出的红光都比最冷的天体多。
来源： IAU OAE/Niall Deacon

词汇表: 黑体辐射 , 电磁辐射 , 波长
分类： 物理学

授权许可： 知识共享许可协议 署名 4.0 国际 (CC BY 4.0) 知识共享许可协议 署名 4.0 国际 (CC BY 4.0) 图标

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黑体辐射--紫外线灾难

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为 OAE 制作

图注： 不同温度黑体的辐射曲线。x 轴表示波长，y 轴表示黑体表面每平方米在每个波长下每秒发射的能量。 温度越高的物体，波长越短，发出的最大能量光也越蓝。尽管图中最冷的天体发出的红光达到峰值，但其他较热的天体发出的红光都比最冷的天体多。 虚线显示的是现代量子力学之前的经典理论所预测的辐射量。对于任何温度高于零的黑体，这一预测在较短波长处都趋于无穷大，被称为 "紫外线灾难"。
来源： IAU OAE/Niall Deacon

词汇表: 黑体辐射 , 电磁辐射 , 波长
分类： 物理学

授权许可： 知识共享许可协议 署名 4.0 国际 (CC BY 4.0) 知识共享许可协议 署名 4.0 国际 (CC BY 4.0) 图标

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Chamaeleon Constellation Map

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图注： 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.
来源： Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope
来源链接

词汇表: 视星等 , 天球坐标 , 拱极星 , 星座 , 赤纬 , 赤经（RA） , 南天极 (SCP)
分类： 肉眼天文学

授权许可： 知识共享许可协议 署名 4.0 国际 (CC BY 4.0) 知识共享许可协议 署名 4.0 国际 (CC BY 4.0) 图标

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International Date Line

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图注： The International Date Line (shown here as a solid line) is a specific meridian which roughly follows the meridian of longitude 180°. The International Date Line passes north–south between Russia and Alaska, through the Pacific Ocean including parts of Micronesia and Polynesia, and to the east of Australia/New Zealand before reaching the South Pole on Antarctica. The International Date Line marks the boundary where calendar dates change by one. Therefore, regions to the west of the International Date line are one calendar day ahead of regions to the east. The International Date Line does not always exactly follow the meridian of longitude 180°. This is partly to stop some territory of a country falling on the other side of the International Date Line than the rest of that country (the Aleutian Islands in the United States being a good example). Some countries also choose which side of the International Date Line they lie on. Samoa changed which side of the date line it lay on in 2011. At this point the International Date Line was moved to lie to the east of Samoa having previously passed to the west of Samoa. On the opposite side of the world the dashed line marks the prime meridian (the meridian of longitude 0°). This is a line that passes through the Royal Greenwich Observatory in the UK. All time zones are measure relative to Universal Time which is the zero point for all timezones. The time zones marked at the top of the diagram are the timezones in the shaded regions excluding the effects of daylight savings time.
来源： Maria Cristina Fortuna/IAU OAE

词汇表: 时区 , 世界时（UT） , 本初子午线 , 国际日期变更线
分类： 天文学与社会 , 地球

授权许可： 知识共享许可协议 署名 4.0 国际 (CC BY 4.0) 知识共享许可协议 署名 4.0 国际 (CC BY 4.0) 图标

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