This article reviews the development and frontier challenges of infrared sensing technology in two major domains: "looking upward" for deep space exploration and "looking downward" for Earth observation. In deep space exploration, represented by the James Webb Space Telescope (JWST), this technology is constantly approaching the physical limits of observation through methods such as ultra-large apertures, very long wavelength band, and ultra-low temperature cooling, aiming to reveal the mysteries of the early universe. The article also elucidates the primary evolution of infrared detection payloads aboard various satellites across different eras, highlighting their representativeness and characteristics. Infrared Earth observation technology has progressed from low spatial resolution and a limited number of bands over a wide swath to improved temporal, spatial, spectral, and radiometric resolution over broad spatial and spectral ranges. New technologies such as large-aperture low-background optics, long-wavelength high-sensitivity detectors, on-chip intelligent sensing, and big data twin systems, as well as the large-scale development of "real-time remote sensing" integrating communication, navigation, and remote sensing, and commercial aerospace, will help build the foundation of "Infrared Digital Earth", enhance human beings′ real-time understanding and accurate prediction of the evolution of anomalous events in the Earth′s multi-spheres and various complex cyclic processes, promoting the popularization of infrared Earth observation technology.