✦ Magic and Science in Action
Mo’ Saci Science is a friendly hub for understanding GPS, GNSS and the technology behind knowing where anything is. Satellites, signals and trackers, made clear.
MoSaciScience is not Mosaic Science. Looking for the magazine? Visit Mosaic Science.
operational satellites
altitude in orbit
everyday accuracy
global GNSS systems
Saci is a one-legged trickster from Brazilian folklore who wears a red magical cap. As people who build with science and technology, we think the best ideas come from keeping that childlike wonder alive. So we put “Mo’ Saci” into science, and pointed all that curiosity at one beautifully practical question: how do we always know where things are?
Read our story →Start here
Pick a path. Everything connects.
The 60-second version
A constellation of 30+ satellites circling Earth twice a day, each broadcasting its position and a precise time.
Ground stations that track every satellite, check its health and keep its clock honest to the nanosecond.
The receiver in your phone, car or tracker that listens to several satellites and works out exactly where it is.
The constellations
GPS is one of four global networks circling overhead right now. Most modern receivers listen to all of them at once. Hover a system to follow its satellites.
Fresh from the blog
If you suspect someone is tracking your car, a careful search usually finds the device fast. Here is where hidden GPS trackers hide, how to sweep for them, and what to do next.
Buying a GPS tracker takes two minutes. Using one lawfully takes a little more thought. Here is how ownership, consent and state law decide whether tracking a vehicle is legal.
The blue dot looks certain, but every GPS fix carries an error budget. Here are the real accuracy numbers, what pushes them wider, and how phones and dedicated trackers compare.
Where to go next
We explain the science and do not sell hardware. When readers ask where tracking actually gets used, these are the pages worth a look.
Stay curious
Send it our way. We turn the best questions into clear, friendly guides.