Rainbows appear curved because of the way light is refracted (or bent) as it passes through water droplets in the air. The light enters the water droplet, reflects off the back of the droplet, and then exits the droplet at a slightly different angle, creating the curved shape we see.
No, rainbows can only appear curved due to the way light is refracted through water droplets. However, under certain conditions, such as viewing a rainbow from above, it may appear to be a complete circle.
The order of colors in a rainbow (red, orange, yellow, green, blue, indigo, violet) is due to the way light is refracted and dispersed through water droplets. Each color has a different wavelength, and as the light is bent, the colors separate and create the distinct order we see in a rainbow.
Yes, rainbows can be seen on other planets that have the right conditions for light to be refracted and dispersed through water droplets in the atmosphere. For example, rainbows have been observed on Saturn's moon Titan.
No, not all rainbows look the same. The size, intensity, and even the number of colors in a rainbow can vary depending on factors such as the size and shape of the water droplets, the angle of the sun, and the observer's location. There can also be double rainbows, lunar rainbows, and even supernumerary rainbows, which have additional bands of color.