Why this observatory fires lasers at satellites

NERC's Space Geodesy Facility, hidden away in the English countryside, fires lasers at satellites. Because it turns out that knowing a satellite's position exactly is really, really difficult. More about the Facility: http://sgf.rgo.ac.uk/ Thanks to Jay Dickieson for the suggestion! 🟥 MORE FROM TOM: https://www.tomscott.com/ (you can find contact details and social links there too) 📰 WEEKLY NEWSLETTER with good stuff from the rest of the internet: https://www.tomscott.com/newsletter/ ❓ LATERAL, free weekly podcast: https://lateralcast.com/ https://youtube.com/lateralcast/ ➕ TOM SCOTT PLUS: https://youtube.com/tomscottplus 👥 THE TECHNICAL DIFFICULTIES: https://youtube.com/techdif