On June 12, at the International Grand Science Program Forum of the Second "the Belt and Road" Science and Technology Exchange Conference held in Chengdu, Sichuan Province, the leading unit of the International Meridian Circle Program (IMCP), the National Space Science Center of the Chinese Academy of Sciences, signed cooperation agreements with the Solar Geophysical Science Committee of the International Association for Science and Technology, the Korean Polar Research Center, the National Space Research and Development Agency of Nigeria, Thailand's Xianhuang University of Technology, and Uganda's Muni University. This marks the scientific community's pioneering launch of the International Meridian Circle Science Program. The Earth's space mainly includes the upper atmosphere, ionosphere, and magnetosphere over 100 kilometers above the Earth's surface, up to the top of the magnetosphere about 10 Earth radii, which is the most closely related space area to human activities in the solar terrestrial space. Affected by solar activity, the Earth's space environment can undergo sudden and frequent drastic changes, and even trigger non-traditional natural disasters, known as space weather. The monitoring, forecasting, and response of space weather are global challenges that require the joint efforts of global space weather monitoring and research forces to carry out scientific breakthroughs. In March 2025, the second phase of the national major scientific and technological infrastructure, the Ziwu Project, officially passed the acceptance inspection and established the most comprehensive space weather ground-based regional monitoring network in the world. On the basis of the Meridian Project, Chinese scientists took the lead in advocating the establishment of the most complete monitoring chain for the meridian circle from 120 ° E to 60 ° W on land, expanding and forming a globally integrated multidisciplinary and multi-element detection network to achieve three-dimensional observation of the solar terrestrial space environment at all latitudes, all weather, and without setting sun; At the same time, combined with space-based exploration, we will conduct in-depth research on the characteristics and changes of the Earth's space environment, reveal the mechanism driven by both solar eruptions and Earth activities, construct a data-driven space weather model and high-precision forecasting products for the international meridian circle, and provide scientific basis for responding to global space weather disasters, peaceful use of space, and promoting the construction of a community with a shared future for mankind in the field of outer space. Wang Chi, director of the National Space Science Center of the Chinese Academy of Sciences and academician of the CAS Member, introduced that the International Meridian Circle Science Program aims to build a global monitoring chain of the solar terrestrial system and decode the process and laws of space weather. Its scientific goal is to recognize a system - the Earth's space system; Clarify two influences - the top-down influence from solar activity and the bottom-up influence from the Earth system; Uncovering three major challenges - the multi factor, multi temporal and spatial scale characteristics and change patterns of global and typical regions in the space environment, the propagation and evolution of solar eruptions in the solar terrestrial space, the relationship between space weather and global change, and natural disasters on Earth. At the same time, in order to achieve scientific goals, the International Meridian Circle Big Science Program plans to establish the "IMCP International Organization" to coordinate and promote the implementation of the International Meridian Circle Big Science Program as a whole, and complete four major tasks including "conducting innovative research, organizing collaborative monitoring, sharing data information, and deepening cooperation and exchange". It is reported that as of now, the International Meridian Circle Science Program has signed cooperation agreements or confirmed cooperation intentions with 36 international organizations and foreign research institutions, including the International Association for Science and Technology's Committee on Solar Terrestrial Physics and the International Committee on Space Research. Wang Chi revealed that the International Meridian Circle Large Science Program will be implemented for at least 11 years, completing the exploration and research of the solar terrestrial space environment for more than one solar activity cycle, building a space weather community with extensive participation and close cooperation among world scientists, "using diverse observation methods and global layout to promote major theoretical innovations and breakthroughs in detection technology in the field of space weather, providing scientific support for enhancing the ability to defend against global space weather disasters, and providing unique solutions and important contributions to the understanding of a livable Earth and the peaceful use of outer space. (New Society)