Why does satellite internet have such different latency?
Because latency over satellite is dominated by orbital altitude, and the difference between orbits is a factor of forty.
Geostationary orbit (GEO), at roughly 35,786 km. A satellite there orbits at the same rate the Earth turns, so it appears fixed in the sky — which is why a dish can be aimed once and left.
The cost is geometry. A signal must travel up and back down, and the reply must do the same: four traversals of 35,786 km, over 140,000 km in total. At the speed of light that is around 480ms of pure propagation delay, before any processing. In practice round-trip times of 600ms or more are typical.
Low Earth orbit (LEO), at roughly 550 km — sixty times closer. Propagation delay falls to a few milliseconds, and real-world latency of 20–50ms is achievable, comparable with many terrestrial connections.
The trade-off LEO makes. A satellite at that altitude crosses the sky in minutes, so:
You need a constellation — thousands of satellites, so one is always overhead.
The terminal must track and hand over between satellites continuously, which is why LEO dishes are electronically steered phased arrays rather than simple reflectors.
Ground stations or inter-satellite laser links are needed to get traffic back to the terrestrial internet.
Satellites deorbit within a few years and must be continually replaced.
What latency actually affects. Bandwidth can be high on both; it is interactivity that differs. GEO makes video calls awkward, gaming impractical, and web browsing sluggish because each page involves many round trips. Streaming works fine on either, because it buffers.
Other characteristics of satellite links: rain fade, where heavy precipitation attenuates the signal, more pronounced at higher frequencies; shared capacity per beam or cell, so performance depends on local subscriber density; and a clear view of the sky requirement that trees and buildings defeat.
MEO sits between the two and is used for some services.
Where satellite genuinely wins: anywhere terrestrial infrastructure is absent or uneconomic — remote properties, ships, aircraft, disaster response and temporary sites.