PT2124 EXO TERRA Moonlight 40 watt – The bulb simulates natural moonlight to allow nootumal vlewlng without disturbing the animal? day and night cycle. The light emitted is bluish due to the use of blue glass. The heat generated by the bulb is minimal but enough to provide tropical night time temperatures. The lower wattage of these bulbs does not interfere with natural night drops in temperature.