Though sadly millilightseconds is not supported on macOS, at least, so you have to go: 3 millilightyears / 365 / 86400 Of course, round 365 to whatever av

Though sadly millilightseconds is not supported on macOS, at least, so you have to go: 3 millilightyears / 365 / 86400 Of course, round 365 to whatever average number of days you believe in :-)