Question

how we are able to see planets and sun colours in vacume in space

Answer 1

The brightness (lack of darkness) that you are used to outdoors on a sunny day is different than what you would see in the vacuum of space. Sunlight falling on Earth is scattered by the molecules in the atmosphere. Short wavelength light is scattered most, which gives you a blue sky (mainly from nitrogen molecules scattering light). Because the light is scattered, some of it reaches your eye regardless of the direction you are looking. Also, unlike space, the great outdoors has many objects around you: the ground, water, buildings, plants, cars, etc which all reflect some light towards your eye, increasing the appearance of being surrounded by light.

In space, there is no atmosphere to scatter the light towards your eye, and depending on the direction you are looking, nothing to reflect the light towards your eye. This means, unless you are looking directly at a light source, or something reflecting a light source (ie: the earth, the shuttle, the ISS), the non-lit area would appear dark. However, if you look directly at a light source, such as the sun, the intensity of the light would appear much brighter than from Earth because there is no atmosphere to scatter some of the light away from your eye.