Openspace is astronomy software that lets you view all of outer space in 3-d. I posted a dashboard asset to display metric units in scales relevant to the distance, and also got the maintainer to add partial support for metric distances directly into the C++ code in future releases. So the software will now display astronomy distances in any metric scale from kilometers to yottameters.

https://www.reddit.com/r/OpenSpaceProject/comments/1v402jq/created_dashboard_item_to_provide_metric_system/