Is there a VGA to Thunderbolt/mini DisplayPort adapter?
VGA is an analog signal and your Cinema requires digital so you need more than a simple cable. You need an appropriate interface box, called a VGA to DVI Scaler, such as the Gefen VGA to DVI Scaler Plus. (Shown for reference only—this is not a recommendation.)

You will also need the appropriate adaptor to use the DVI signal with your monitor.

Please note that I don't have experience with these products and can't guarantee results—particularly if your Display is the thunderbolt-equipped model. Contact the vendors to assure yourself that it will work.