Big data has been a focus of research in science, technology, economics, and social studies. Many countries have already incorporated big data research into their national strategies. This paper elaborates upon the origin, connotation, and development of big data from both a spatial and temporal perspective. It proposes that scientific big data will become a new solution in scientific research as the paradigm changes from being model-driven to data-driven. This paper defines the concept of “scientific big data” and proposes strategies for solving “big data problems”. Theoretical frameworks and data systems for Digital Earth are discussed with a clear conclusion that scientific big data is a prominent feature of Digital Earth. As an example, spatial cognition of the formation mechanism of China’s Heihe-Tengchong Line—a geo-demographic demarcation line dividing China into two parts—is discussed within the context of big data computation and analysis for Digital Earth.