  ESASky is a science-driven discovery portal to explore the multi-wavelength
sky and visualise and access multiple astronomical archive holdings. The tool
is a web application that requires no prior knowledge of any of the missions
involved and gives users world-wide simplified access to the highest-level
science data products from multiple astronomical space-based astronomy missions
plus a number of ESA source catalogues. The first public release of ESASky
features interfaces for the visualisation of the sky in multiple wavelengths,
the visualisation of query results summaries, and the visualisation of
observations and catalogue sources for single and multiple targets. This paper
describes these features within ESASky, developed to address use cases from the
scientific community. The decisions regarding the visualisation of large
amounts of data and the technologies used were made in order to maximise the
responsiveness of the application and to keep the tool as useful and intuitive
as possible.
