Mare Crisium - Sea of Crises

图像

图注： The image shows the lunar Mare Crisium, the “Sea of Crises,” as seen by NASA’s Lunar Reconnaissance Orbiter in 2015. The photo size is 750 × 750 km, about the size of Germany. Mare Crisium is located in the Moon’s Crisium basin, near the great Mare Tranquillitatis on the near side of the Moon. It is visible from Earth and is characterized by a relatively smooth and flat surface surrounded by cliffs and highlands. The basin that now contains the Mare Crisium was formed by a massive impact event likely during the Nectarian period approximately 3.9 billion years ago. During this time in lunar history, major basins including the Crisium basis were formed by large impact events. Later in lunar history, the basin was flooded by lava to form the dark and flat plain we see today. Its floor is about 1.8 kilometers below the typical lunar surface level. The study of lunar maria provides insights into the volcanic history and impact processes that have affected the Moon and other celestial objects.
来源： NASA, Lunar Reconnaissance Orbiter
来源链接

词汇表: 月球 , 月海
分类： 太阳系

授权许可： 公共领域 公共领域 图标

文件 ( 图像 6.78 MB)

The Pillars of Creation in comparison

图像

图注： The 'Pillars of Creation' are a renowned astronomical feature situated within the Eagle Nebula in the Serpens constellation. The illustration provides a direct comparison between images captured by the Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST), showcasing the pillars, which span several light years in diameter, in both visible light (also known as optical light) and infrared light. On the left are the pillars as seen by Hubble in visual light, taken in 2014. It displays dark pillars against an opaque background, with only a handful of visible stars. Conversely, the counterpart on the right is Webb’s near-infrared view published in 2022, penetrating the dust and revealing numerous stars of varying sizes. Their distance from Earth is approximately 6,500 to 7,000 light years. Within these pillars, new stars are constantly forming, making them a subject of extensive study by astronomers. Composed mostly of cool molecular hydrogen and small amounts of interstellar dust, they are subject to erosion by the intense ultraviolet radiation emitted by nearby massive and newborn stars, a process known as photoevaporation.
来源： NASA, ESA, CSA, STScI
来源链接

词汇表: 红外天文学 , 红外望远镜 , 光学天文学 , 恒星形成 , 可见光谱 , 尘埃云
分类： 银河系与星际介质 , 恒星

授权许可： 知识共享许可协议 Attribution 2.0 Generic 知识共享许可协议 Attribution 2.0 Generic 图标

文件 ( 图像 12.03 MB)

Map of de-facto time zones on Earth

图像

图注： Due to the Earth's spherical shape and its rotation around its own axis, local noon – the moment in time when, for an observer at a specific geographic location, the Sun reaches its highest position in the sky varies with longitude. That is why a time coordinate, such as Universal Time (UT or UTC), might be of advantage for specifying moments in time in a unified way. But a global time coordinate will be out of synch with the local day-night rhythm in most locations on Earth. A compromise is to divide Earth into zones each comprising 15 degrees of longitude, and in each zone define time as UTC plus or minus an integer number of hours, with the offset chosen so as to make time match as closely with local time at the middle longitude of the time zone. In practice, political considerations have altered the time zone boundaries somewhat. When a country straddles several time zones, it is not uncommon for the country's government to choose one of those time zones to define the country's official time. This map, originally created by the CIA and updated by several Wikimedia Commons users, shows the current definitions of the world's time zones. The IAU OAE is not the original author of this map. The designations employed and the presentation of the material on this maps do not imply the expression of any opinion whatsoever on the part of the IAU or the IAU OAE concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
来源： Wikimedia Users UnaitxuGV, Heitordp and others based on a map created by the U.S. Central Intelligence Agency (CIA)
来源链接

词汇表: 格林尼治标准时区（GMT） , 经度 , 时区 , 世界时（UT）
分类： 地球

授权许可： 公共领域 公共领域 图标

文件 ( 图像 2.88 MB)

Pioneer Plaques

图像

图注： The Pioneer 10 and 11 spacecraft are the first human-made objects to leave the solar system and venture into interstellar space. To inform potentially intelligent species about our existence, they both carry small metal plaques identifying their time, place of origin and information about their builders. They provide the location of our solar system in the Milky Way by depicting the Solar System's position relative to 14 pulsars, with radiating lines that include information about their frequencies. A model of a hydrogen atom undergoing one particular atomic transition is depicted. The wavelength and frequency of this transition are used to express sizes and frequencies of the other items shown in the plaque. A more detailed view of Earth's position in the solar system, with the spacecraft's trajectory moving away from Earth, passing Mars and Jupiter is displayed at the bottom. The plaque also depicts a naked man and woman alongside the spacecraft to provide a sense of scale. The man’s hand is raised as a friendly gesture. The 6-inch by 9-inch gold-anodized aluminum plate has the design engraved on it. It was attached to the support struts of the spacecraft's antenna to try to to protect it from erosion by any interstellar dust the spacecraft may encounter on its journey. Designed by Carl Sagan and Frank Drake, with artwork by Linda Salzman Sagan, these plaques are meant to communicate the origin of the spacecraft to any extraterrestrial life that might encounter them. While Pioneer 10 is on a course towards the star Aldebaran in the Taurus constellation, which will take about two million years to reach, Pioneer 11 is heading in a different direction towards the constellation of Aquila. It will take approximately four million years to pass close to some of the constellation’s stars.
来源： NASA Ames
来源链接

词汇表: 外星智能
分类： 天文学与社会 , 系外行星与天体生物学 , 太空探索

授权许可： 公共领域 公共领域 图标

文件 ( 图像 5.94 MB)