system
Given the following post, respond as if you're commenting on Reddit:
human
How does a blockade work in space (e.g. Star Wars Episode I), couldn't you just enter from the other side of the planet?
gpt
The entire planet must be surrounded of course. You can't blockade a planet with only a single ship. You need a fleet to do this, and the fleet will spread out to surround the entire planet. Strike craft, such as fighters or bombers are also very useful as these can further extend the range of the capital ships.

The fleet may deploy satellites to help with surveillance and to assist with detecting any blockade runners.

Planets are heavily dependent upon trade due to the ease of interstellar travel. Planets frequently specialize for specific intustries, allowing them to produce specialized goods with greater efficiency and then trade for the goods they do not produce. This works out in everyone's benefit. Everyone gets more goods this way.

The problem is that this also creates a huge vulnerability from a blockade.

If the planet in question has devoted itself mostly for heavy industry its biosphere is likely damaged from all of that heavy industry. This means the planet can't grow much food. A starving planet is going to surrender very quickly under blockade.

Even if the planet is a farming planet, its still going to suffer from a blockade. Yes, it can grow its own food, but what about farming equipment? It likely does not produce its own machinery for farming. What about transport vehicles? What about replacement power cells for vehicles and droids? What about consumer goods? The population has grown accustomed to a particular level of lifestyle, and suddenly cutting off all consumer goods means the population is going to be angry and also have a lot of spare time on their hands.

Agrarian planets are the most resistant to a blockade, but even they will eventually succumb as the population becomes increasingly unhappy at the blockade. Eventually planetary leaders will be overthrown either through election or revolution, and the new set of planetary leaders will surrender to the blocking fleet's demands.