From single cells to our planet-recent advances in using mass spectrometry for spatially resolved metabolomics.

Spatial information in the form of 3D digital content has been increasingly integrated into our daily lives. Metabolomic studies parallel this trend with spatial and time resolved information being acquired. Mass spectrometry imaging (MSI), which combines qualitative and quantitative molecular information with spatial information, plays a crucial role in mass spectrometry-based metabolomics. The lateral spatial resolution obtained by MSI continues to improve and allows mass spectrometers to be used as molecular microscopes-enabling the exploration of the cellular and subcellular metabolome. Towards the other end of the scale, MS is also being used to map (image) molecules on our skin, habitats, and entire ecosystems. In this article, we provide a perspective of imaging mass spectrometry for metabolomic studies from the subcellular to planetary scale.