: : : My 10 year old niece has a science question from her teacher. Does gravity affect light, and can it be bent? : : : Any help would be great.

: : You, physically, cannot bend light, yet if light is passing a mass of great quantity, the mass of the light : : will be accelerated by the large mass, and the light will be in the direction of the mass. The amount of bend in the : : beam of light may not be notible, but there will always be a slight bend in the light if it is being accelerated by another mass.

: Are you saying that photons have mass? I thought this wasn't so?

:You say: The mass of light will be accelerated. Not true! Mass can not travel at the speed of light in the first place, only energy. Second the speed of light is a universal constant and cannot be accelerated. It's called a universal constant because it will move at 300,000 kps no matter what perspective you look at it from. For example, if you are riding in a car traveling 60 mph and you throw a baseball out of the window at 10 mph, naturally the baseball will be traveling at 70 mph. If you are riding in the same car and say you shine a flashlight out the window, the light will not be affected by the speed of the car. It will still travel at 300,000 kps. Anyway, sorry about getting off the subfject. Yes, light can be bent by a massive object. Have you daughter use this example and she will be be o.k. The reason the sunrise and the sunset are red, is because light from the sun is being bent by the earth's gravity. When the sun is directly above your position on earth, it is noon, and the sky appears blue. This is because white light is made up of all colors. The colors of light have different wave lengths. Blue is on the shorter side, therefor when light travels through the atmosphere to your eyes, more of the blue light waves make it through. The wider waves are blocked by the particles in the atmosphere. Now when the sun begins to set at the horizon, the light from the sun has a greater distance to travel to get to your eyes than it did when it was directly above you. You can actually see the sun for a few minutes after it sinks below the horizon because the light is bending around the earth. Anyways, since the light is bending and therefor has a farther distance to travel, (remember the shortest distance between two paths is a strait line, like when the sun is above you) then it also has more obsitcles (or particles) to travel through. So, now even the short blue waves get blocked and only the shortest waves make it to your eyes. The shortes visible waves are the redish colored waves and bam!!! you get a sunset.