The statement that there is no light in outer space is not entirely accurate. Outer space is not completely devoid of light, but it is characterized by extremely low densities of matter, including gas and dust particles, which are necessary for light to interact and be scattered or absorbed.
In the vast expanse of space, there are numerous sources of light, such as stars, galaxies, and other cosmic objects. These sources emit electromagnetic radiation, including visible light and various other wavelengths across the electromagnetic spectrum. However, light travels in straight lines unless it interacts with matter.
When light passes through a medium like our atmosphere or interstellar space, it can be affected in several ways. In our atmosphere, light interacts with gas molecules, water vapor, and dust, scattering and absorbing certain wavelengths. This scattering is responsible for phenomena like the blue color of the sky during the day.
In interstellar space, there are much lower densities of matter, and thus light encounters fewer obstacles. However, it can still interact with the thin interstellar medium, consisting of gas and dust clouds. These clouds can absorb and scatter some of the light passing through them, leading to the phenomenon known as interstellar extinction. However, even in these cases, some light manages to travel long distances and reach us, allowing us to observe stars and other celestial objects.
So, while space may appear dark to the human eye due to the lack of a substantial medium to scatter and reflect light, there are indeed sources of light out there, including planets, stars, galaxies, and other cosmic objects. Scientists have developed instruments and telescopes capable of detecting and analyzing these various forms of light, enabling us to explore and understand the vastness of the universe.