An astronaut in outer space, far from the atmosphere of the Earth, will observe the sky to appear in which colour?

Introduction / Context:
This general science question asks about the appearance of the sky to an astronaut in outer space. On Earth, we are used to seeing the sky as blue during the day, mainly because of the scattering of sunlight by the atmosphere. In space, however, conditions are very different, and understanding this difference helps clarify basic concepts in optics and atmospheric science.

Given Data / Assumptions:

• The observer is an astronaut in outer space, not within the lower layers of the Earth's atmosphere.
• The astronaut is looking at the sky, that is, the region away from the Sun and other bright celestial bodies.
• We assume that there is essentially no atmosphere around the astronaut in deep space.

Concept / Approach:
On Earth, the sky looks blue because molecules and small particles in the atmosphere scatter shorter wavelength blue light more than other colours, a phenomenon called Rayleigh scattering. In outer space, there is no appreciable atmosphere to scatter sunlight. Without scattering, there is no diffuse light filling the sky. The astronaut sees bright points where stars, planets or the Sun are located, and darkness elsewhere. This darkness appears as a black sky, even when the Sun is shining on the astronaut.

Step-by-Step Solution:
Recall that colour perception depends on light reaching the eye from different directions. On Earth, the atmosphere spreads sunlight across the sky, so we see a blue dome. In outer space, the vacuum has extremely few particles. Without air molecules, sunlight travels in straight lines and is not scattered into other directions. Therefore, except along the direct line of sight to the Sun or illuminated objects, there is no light coming from other directions. Where there is no light, the human eye perceives black. As a result, an astronaut in space sees the Sun as a very bright disc, stars as bright points, and the background as a black sky. This leads directly to the conclusion that the sky appears black in outer space.

Verification / Alternative check:
Photographs taken from spacecraft, the International Space Station and during Moon missions consistently show a black sky, even when the surface of the Moon or parts of the spacecraft are brightly lit by the Sun. These images confirm the theoretical explanation: in the absence of an atmosphere to scatter light, space remains dark except where objects are directly illuminated. Thus, the astronaut's personal observation matches what we see in space photography and physics textbooks.

Why Other Options Are Wrong:
Option A, white, would require uniform bright light coming from all directions, which does not occur in vacuum. Option C, blue, is the colour characteristic of Earth's daytime sky due to atmospheric scattering, but the astronaut in space is above most of the atmosphere and will not see a blue dome. Option D, red, is sometimes seen at sunrise or sunset on Earth due to scattering of other wavelengths, but again this effect relies on atmosphere. None of these colours describes the appearance of the sky in deep space.

Common Pitfalls:
Some candidates mistakenly transfer their everyday experience of a blue sky on Earth directly to space and choose blue. Others think of images of nebulae or galaxies and imagine a colourful sky. However, such images are often long exposure photographs or enhanced. To avoid this mistake, focus on the presence or absence of atmosphere and the role of scattering: without it, space looks black except for discrete luminous bodies.

Final Answer:
An astronaut in outer space will observe the sky to be black, so option B is correct.