You have to attack it with ground troops. Go to the Colonies screen, select the planet with it and then go to the "Facilities" tab. You should be given the option to attack it once you select it.

It's mainly used for fleet posture.

This thread will tell you pretty much everything you need to know. matrixgames.com/forums/tm.asp?m=2973167

<t> Does anyone get performance drops when you zoom in or out? This usually occurs during the colonization phase.<br/>
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Also after I click on the top menu for fleets or ships, it lags and takes 3-5 seconds to come up.<br/>
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I've already tried reducing nebula quality and star density ...

Thanks for making this guide! It really cleared up my confusion about how to use resupply ships.

Also,where do you see the total amount of fuel your fleet needs?