If an object were to be thrown at a speed close to the speed of light, several interesting phenomena would occur due to the effects of special relativity. However, it's important to note that achieving such velocities is currently beyond the realm of our technological capabilities, and this scenario is purely hypothetical for now.
As an object approaches the speed of light, its mass would increase significantly according to the relativistic mass-energy equivalence. The object would require an enormous amount of energy to accelerate it to such speeds, and the effects of relativity would become more pronounced.
From an observer's perspective, if they were able to witness the object traveling through the air towards its target, several visual effects would become apparent. These effects are a result of time dilation, length contraction, and relativistic aberration.
Time Dilation: Time would appear to slow down for the object as it approaches the speed of light. The object's internal processes, such as the ticking of a clock on board, would appear to slow down when observed from a stationary reference frame. This means that, relative to an outside observer, the object would seem to move in slow motion.
Length Contraction: From the observer's point of view, the length of the object in the direction of its motion would appear to contract. This contraction is a consequence of relativistic effects and would make the object appear shorter in the direction of travel.
Relativistic Aberration: The light emitted or reflected by the object would undergo relativistic aberration, causing the object to appear distorted or foreshortened in the direction of motion. This effect is similar to how a straw in water appears bent due to the refractive index of water.
As the object moves through the air, the air molecules would be affected by its high velocity, resulting in interactions such as ionization and the creation of shockwaves. These effects would depend on the specific conditions and properties of the object and the surrounding medium.
It's important to note that these effects become more pronounced as the object's speed approaches the speed of light. However, as mentioned earlier, reaching such speeds with macroscopic objects is currently not feasible with our existing technology.