Power-Button Symbols on a Laptop
Laptops use a variety of power-button symbols, some common and some obscure. Blessed is the laptop owner whose laptop's power button has a symbol on it. And wise is he who recognizes the symbol as that of the power button. Let it be so. Amen.
The below figure displays a sordid sampling of laptop computer power-button symbols.
The moon icon in the above figure labels a sleep button. This might be in addition to the power button, although on most modern laptops the sleep button and power button are one and the same.
The moon icon is still used on many laptops to indicate when the computer is in sleep, or standby, operation. So, you may find that symbol on your laptop row-of-symbols and lights thing, but not associated with any specific button.