Astronomy

This article answers the question "Will a planetary conjunction cause disasters on Earth?" by introducing the definitions of planetary conjunction and five-star conjunction, explaining that the gathering and dispersing of planets is a normal astronomical phenomenon, stating that the saying "auspicious omens appear in the sky" was flattery from ministers in the feudal era, and that the gravitational superposition of planetary conjunctions will not trigger disasters on Earth.

This article focuses on the phenomenon that Venus transits occur at intervals of 8 years and sometimes require more than 100 years between transits. It explains the formation reasons and laws of this phenomenon from the perspectives of the orbital period of Venus and the Earth, the angle between the orbital planes, the conjunction period, and the influence of celestial gravity.

This article explains the formation principle of the phases of the moon and the appearance time and positional characteristics of different phases of the moon, such as the new moon, the waning moon, the crescent moon, the gibbous moon, and the crescent moon. It also explains that "a half-moon rising" is never the cause of the crescent moon, and at the same time, it confirms that the phase of the moon in the Tang Dynasty poem "Mengqiao Night Mooring" is a crescent moon.

This article addresses the question of "why the moon on the horizon appears particularly large", explaining that this phenomenon is an illusion and introducing various causal explanations such as the Ponzo illusion, the influence of distance perception, and the visual-motor effect. It points out that there is currently no universally accepted answer to this question.

This article focuses on the question of "why some stars in the sky are bright and others are dim", explaining that the brightness of stars is determined by their own luminosity (proportional to the surface area and surface temperature of the star to the fourth power, with less luminosity called dwarf stars, more luminosity called giant stars, and extremely high luminosity called supergiant stars) and the distance to the observer (brightness is inversely proportional to the square of the distance), and introduces the concepts of apparent magnitude and absolute magnitude, showing that only absolute magnitude can reflect the true luminosity of stars.

This article focuses on the topic of astronomers measuring the distances to celestial bodies, and introduces the principles, application scopes, and related scientific discoveries and research progress of various measurement methods, including the triangulation parallax method, photometric distance measurement methods using standard candles such as Cepheids and Type Ia supernovae, and the Hubble's law redshift distance measurement method.

This article focuses on the question of "why should the moon become the new home of telescopes", introducing the advantages of space telescopes compared to ground-based telescopes, as well as the control difficulties and interference from Earth's obstruction faced in the construction of large space telescopes. It explains that the moon, with multiple advantages such as no atmospheric interference, low gravity, weak geological activity, and the ability to expose observations of distant and faint objects for longer periods of time, is suitable as a new location for telescope construction.

This article focuses on the topic of "why send telescopes into space", introducing that the Earth's atmosphere absorbs X-rays, gamma rays, and other multi-band electromagnetic waves emitted by celestial bodies, and atmospheric turbulence can reduce observation resolution, so it is necessary to send telescopes into space. It also explains the launching methods of telescopes corresponding to different observation bands, and mentions the Hubble Space Telescope and its successor, the James Webb Space Telescope.

This article focuses on the question of where it is better to build an observatory, and introduces the reasons why mountains and deserts are suitable for building observatories, as well as the advantages of Antarctic Ice Dome A as a more optimal observation site and the related situation of China's construction of the Antarctic Survey Telescope there

This article focuses on the question of why many small mirrors are used to assemble a large mirror surface. Taking the Keck telescope as an example, it introduces the technology of assembling mirror surfaces and explains that large-diameter single-piece telescope lenses face problems such as difficulty in supporting infrastructure, transportation difficulties, high manufacturing costs, etc. Assembling mirror surfaces can solve these problems, but it requires overcoming technical challenges such as collimation and phase matching.

This article focuses on the question of what the next-generation astronomical telescopes will be like, introducing the large aperture of the mosaic mirrors of the world's top-tier astronomical telescopes, the two mainstream models of multiple telescopes working in collaboration and representative devices, and elaborating on the parameter characteristics and development of different types of next-generation astronomical telescopes, including large-aperture mosaic mirrors such as the Thirty Meter Telescope and the European Extremely Large Telescope, multi-mirror collaborative telescopes like the Giant Magellan Telescope, and the LSST telescope, which combines large aperture with wide field of view.

This article explains why giant telescopes need to use active optics and fiber optics technology. It points out that active optics technology can actively overcome the problem of mirror deformation in large-aperture telescopes to improve imaging quality, which is divided into two types: spliced mirror active optics and thin mirror active optics. Fiber optics technology can solve the problem of the burden of large-scale backend instruments and measurement accuracy, and also enable multi-target observation to improve observation efficiency.