Ancient Indian knowledge systems, as expressed in texts like the Vedas, Puranas and Surya Siddhanta, hold a deep understanding of solar energy, agriculture, environmental equilibrium and celestial physics. These fundamental ideas, developed over thousands of years, show functional similarities to modern remote sensing applications. For instance, modern techniques like multispectral satellite imagery, NDVI measurement and digital elevation models to quantitatively assess similar variables have parallels to ancient methods for monitoring seasonality patterns, vegetation health and water supplies associated with solar movement, phenology and hydrology. This paper conducts a comparative analysis to investigate the connection between the ancient Indian astronomical, meteorological understanding and contemporary Earth observation techniques. The main question driving this study is how effectively the ancient Indian astronomical and agro-hydrological systems interact with modern remote sensing and environmental monitoring technologies and how this ancient knowledge can support modern sustainability projects? The study uses a comparative framework based on three observable criteria to evaluate this: (i) accuracy of environmental indicators (e.g., lunar phases vs. satellite-based phenology) (ii) temporal alignment of crop calendars and (iii) spatial correlation between traditional water harvesting practices and GIS-based watershed models. For instance, seasonal farming guidance was provided by ancient Indian Nakshatra-based farm calendars synchronized with solar-lunar cycles. The technique is still applied in climate-based crop modelling today. Similarly, site-oriented hydrological design principles used today in contemporary-day watershed planning as well as in remote sensing-derived water assessments are encapsulated by traditional water-harvesting structures like stepwells and johads. Surya Siddhanta provides clear-cut calculations of the distances of planets and the Earth’s circumference, display a mathematical finesse that is equivalent to recent heliocentric theories and geodetic data. Whereas, the advanced water conservation and preservation techniques of the Harappan civilization include reservoirs, canals and drainage systems which align with today’s hydrological principles and sustainable irrigation practices. Ultimately, this research contributes to the growing discourse on the relevance of indigenous and ancient knowledge systems within contemporary scientific fields. The integration of historical knowledge with modern technological advancements not only enriches scientific dialogue but also emphasizes the necessity of all inclusive, interdisciplinary methods to address issues related to water resources, climate variability and global agricultural sustainability.