The color of an object that is observed is determined by the properties of light, the object's interaction with light, and the perception of color by the observer. The speed at which an object moves does not directly determine its color when observed.
Color is a result of the interaction between light and matter. When light interacts with an object, it can be absorbed, transmitted, or reflected. The object's material composition and surface properties determine how it interacts with different wavelengths of light. The wavelengths of light that are reflected or transmitted by the object then determine the colors we perceive.
The perception of color is based on the wavelengths of light that reach our eyes. Our eyes contain specialized cells called cones that are sensitive to different ranges of wavelengths. When light enters our eyes and interacts with these cones, it stimulates them, and our brain interprets this stimulation as different colors.
The speed at which an object moves relative to an observer can affect the perceived color, but this is due to a phenomenon known as the Doppler effect. The Doppler effect describes how the perceived frequency or wavelength of waves, including light waves, changes relative to an observer when the source of the waves and the observer are in motion relative to each other.
If an object is moving away from an observer, the perceived wavelength of the light it emits or reflects will be longer, resulting in a shift towards the red end of the visible spectrum (known as redshift). Conversely, if the object is moving towards the observer, the perceived wavelength will be shorter, resulting in a shift towards the blue end of the spectrum (known as blueshift).
However, it's important to note that the Doppler effect primarily affects the perceived wavelength and not the intrinsic color of the object. The actual color of an object, determined by its interaction with light, remains the same regardless of its motion.