But creating the nanostructure—a few thousandths the size of a living cell—wasn't as simple. A team of materials engineers and chemists worked together using DNA to assemble the structure. Constructed to resemble a planet, the nanostructure, also named the "core-satellite," has smaller moons tethered to it by strands of DNA, essential not only as glue but also as a biological component to recognize other molecules within a living organism. When faced with the right DNA molecules, the DNA tethers contract and expand and the satellites move in relation to the core, altering the optical properties of the structure. Since the structure is able to absorb and scatter light as the structure changes, researchers can tell what is happening at a molecular level by measuring color changes. Such measurements could provide essential information about cell processes to the medical and scientific fields.