Watch LaterAdded 05:19 說太空 Yes, scientists are actually building an elevator to space – Fabio Pacucci
Watch LaterAdded 04:20 說太空 Why is NASA sending a spacecraft to a metal world? – Linda T. Elkins-Tanton
Watch LaterAdded 05:30 說太空 Light seconds, light years, light centuries: How to measure extreme distances – Yuan-Sen Ting