Help! How to avoid these Invasions

Only those ships that are in orbit will defend the planet automatically, not those ships surrounding the planet.

When ships are built they are "in orbit". After you have launched them, you can put them back into orbit by sending them directly to the planet (click on the actual planet!)

And only one ship can defend at a time, unless you have the orbital fleet manager on that planet.

Hope this helps!

Always keep at least one Ship in orbit.

I normally have about two small ships with some weapon in orbit on each of my planets (and no orbital fleet manager)

I think hes talking about sentry. Thier right sentry doesn't work that way. You have to keep some ships in orbit.

I wish sentry worked liked that.

This is where sensors help, if your sens range is less than the attacker's speed you will not see the fleet coming until they get to your planet.

I find also that zooming out all the way (until you get to the symbols) helps me spot enemy fleets coming in.

But the bottom line is that you have to run the intercepts yourself.

V1m advises paying attention whilst at war!

Once you Launch a ship from a planet it will no longer auto defend.
Orbital fleet manager allows the planet to use multiple ships (Up to Logistic Max) for defense. With out it you only use one ship at a time.

So in short never launch all your ships or send some from other faster producing planets if in need of defense.

Once you build the "Eyes of the Universe" each of your ships will have a sensor range of 15. Place FAST fleets along your borders to intercept any incoming threats. You will have to spot the threats and move your ships yourself (no auto feature). This way you can protect your empire with fewer ships.

I actually advise NEVER defending your planets with ships in orbit as long as you have a military left (if you don't have any military, a bunch of junk ships in orbit can stall the AI while you rush build). If your planets are technically undefended, the AI--even at the very highest difficulty levels--will send its transports unescorted to make "attacks of opportunity" against your "undefended" worlds. If you're paying attention, which you should be, you can simply pick them off with your fleets (or dinky 1-attack tiny little crap ship). Tactical geniuses they are not.   

On the other hand, if you officially guard your planets, the AI will send in warships to clean yours out.  

Don't guard your planets with ships in orbit. Its a waste of good ships. If the AI declares war, and you have a standing military that's equal to it, INVADE! Turn all research to weapons and seize the intiative. When the AI declares war, it doesn't attack immediately, and has its ships unstrategically positioned through its empire.

Strike fast and hard at a few high quality (near) planets, and build transports. Your ships should manage to wipe 'em out and take the planets. After that, patrol aggressively (read 10+ moves away) from the planet, and make sure you have long range sensors. If you can't see 'em, you can't shoot em.

And never hit the turn button twice. That's just asking for it.

Don't guard your planets with ships in orbit. Its a waste of good ships. If the AI declares war, and you have a standing military that's equal to it, INVADE! Turn all research to weapons and seize the intiative. When the AI declares war, it doesn't attack immediately, and has its ships unstrategically positioned through its empire.

Which is why I ask the devs to force the AI to never declare war except if he is ready to take on the initiative IMMEDIATLY, like every warlord would do when he opens fire.

If you have the economy to support the extra ships or have few enough planets, it's worth having a little extra insurance, and besides your ships get bonus to attack power while it's in orbit. But yeah just pay attention to your borders and space and no enemy can break through.

I would not recommend keeping planets unguarded. If an unescorted transport gets through you will lose a lot of population, even if you win.