How come Edward sparkles under a light?

I guess bcuz it wasn't enuff light? Idek. Maybe there was most light when she waas being born??? Idek... Isn't there a like windom on the roof of they're house? I'm not so sure. But, maybe bcuz of tht reason?

well it is fork washington it is aways raining so there is no sun, becuse they dont go too school when it is sunny. in the house it is basacle made of glass so the sun would get in it. is the only place they dont have too hide so there is glass windows becuse every once in a while vampire want too see the sun too lol:)

because edward only spakels under sun light not light from a light bulb

Edward sparkles in the light but when in school where there is light too,thats because he only sparkles when he gets sunlight not when he gets light from bulbs and he only goes outside when its rainy অথবা dark.

probably not enough light অথবা its bright but no sun