Planetary defense system
A planetary defense system, also called an orbital defense system or planetary defense battery was a network of space-based and/or ground-based defenses intended to protect a planet from attack.

Federation examples

In the 23rd century, Earth was protected by the Earth Defense Network. ()

''In 2258 of the alternate reality, Earth's border protection grids had several access codes which were known to Starfleet captains. Nero captured  and tortured him to learn the codes. ()

The inner Sol system was defended by the Mars Defense Perimeter, which was breached in early 2367 by a Borg cube en route to Earth. ()

In 2369, when Starfleet assumed operational control of Deep Space 9, the station became a planetary defense system for Bajor as one of its main duties was to protect the planet from hostile attack. ()

In 2372, the sabotage of Earth's power relay grid left Earth "defenseless" as sensors, transporters, and surface-based defense installations were taken offline. ()

During the Dominion War, Betazed had antiquated and undermanned planetary defense systems, which proved little match for an invading Dominion force in 2374. ()

By 2385, Mars was protected by a deflector shield and a defense net that included orbiting satellites. These systems were deactivated or compromised by rogue synths during the Attack on Mars. ()

Non-Federation examples

The Romulan Star Empire used cloaked mines to defend recently annexed planets in the 22nd century. () 

In 2267, the  encountered Apollo's hand near the planet Pollux IV. This enormously-powerful force field was capable of stopping the ship from approaching the planet, preventing it from firing its weapons, and also preventing escape. ()

The Aldeans, until 2364, used a high-powered repulsor beam to repel any unwanted ships from Aldea's orbit, as well as a powerful shield and a cloaking device. ()

The Echo Papa 607 weapon system of Minos could act as an effective planetary defense system, repelling attackers in space and on land. ()

A moon in the Gamma Quadrant, home of the Ennis and the Nol-Ennis, had a sophisticated array of orbiting satellites which inhibited transporter functions, and also actively sought out and attacked orbiting vessels. ()

After the Klingon invasion of the Cardassian Union in 2372, the Klingon Empire deployed orbital defense systems around the planets they had captured. ()

The planetary defense systems of Korma included system-5 disruptors. They were overwhelmed by Klingon forces in 2372. ()

A planet of the Mokra Order visited by  in 2372 was defended by numerous surface-based phased ion cannons. ()

Chancellor Gowron moved the Klingon military headquarters from Qo'noS to Ty'Gokor in 2373. Ty'Gokor was protected by a powerful defensive shield and a tachyon detection grid, along with a large number of warships and space stations. ()

In late 2374, during the Dominion War, the Cardassians developed unmanned Cardassian orbital weapon platforms to protect planets. The platforms were deployed in the Chin'toka system and around Cardassia Prime. ()

As of 2399, Vashti possessed a standard Romulan planetary defense system comprised of orbital killer drones, described as "primitive but effective". It had been bought secondhand and installed with the help of the Fenris Rangers. ()

As of 3189 Ni'Var had a network of defense satellites.

Appendices

See also 
 Defense perimeter
 Invasion defense antenna
 Phaser battery

Background information 
A cut bit of dialogue in the script of  would have established that in 2063 Earth did not have planetary defense systems.

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