Celestia Forums

I either have an actual problem or I am being a complete idiot, but I cannot figure out how to install an add on into Celestia. whenever I try to move the add on folders into the Celestia folders (Extras, Textures, ect.) My computer tells me that this operation cannot be completed because Celestia cannot be modified. I have tried to move the folders into many different locations inside Celestia without any luck Including moving the individual add on files into the correct Celestia folders by the file suffix. I am using a second gen. (late 2008 MacBook Pro) with an Intel Core 2 Duo processor and a Nvidia GeForce 9400M graphics chip. Please help!

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Unfortunately I am the systems admin. not only that I am the only one with an account on my notebook there are no guest accounts.

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Why is having only one account bad? and as to the download I just downloaded it from the Celestia website, 1.5 first and then 1.5.1 later on when it was released I don't recall doing anything unusual in the process.