As the environment of space cannot support life, being close to a perfect vacuum and close to absolute zero, life-forms either require a spacesuit or bodily modifications to survive in it when venturing outside of a spaceship or space station.
There are various types of celestial body (天体, Tentai) which can be found in space, including stars (星, Hoshi), planets (惑星, Wakusei, at times referred to by 星, Hoshi), moons (月, Tsuki), asteroids (小惑星, Shōwakusei), comets (彗星, Suisei) and nebulae (星雲, Seiun, occasionally referred to by 雲, Un, Cloud).
Stars come in a variety of spectral classes and sizes, from dwarf stars (矮星, Waisei) to giants (巨星, Kyosei) and supergiants (超巨星, Chō Kyosei). A star with planets orbiting it is also referred to as a sun (太陽, Taiyō). A system of stars and planets is either referred to as a solar system (太陽系, Taiyōkei) or a star/stellar system (星系, Seikei). There are also close groups of stars, referred to as a star cluster (星団, Seidan). Million of stars and stellar systems make up a gigantic cluster known as a galaxy (銀河, Ginga). When large stars reach the end of their lifespans, they can produce an explosion known as a supernova (超新星, Chōshinsei). In the case of the largest stars, the remains of the star can undergo gravitational collapse, forming a black hole (ブラックホール, Burakkuhōru).
Planets are smaller than stars but generally larger than most of the celestial bodies below star size. The size of a planet is linked to what type of planet it is, with the smaller planets mainly being comprised of rocky material while the larger ones, referred to as gas giants, are mainly comprised of gas. Planets are sometimes orbited by smaller celestial bodies, known as moons.
An asteroid is a smaller rocky celestial body than a planet, though not orbiting one as a moon, with large asteroids sometimes referred to as planetoids. Comets are similar icy celestial bodies, which when passing close to a sun, heat up and start outgassing, creating a visible atmosphere around the nucleus known as a coma, sometimes with a tail extending behind the comet.
A nebula is an interstellar cloud of gas and dust, usually vast in size. They are often regions where new stars are formed. Nebulae can also be formed from the remains of stars which have shed their outer layers at the end of their lives. Certain gas clouds may exhibit conditions similar to those found in a storm .
Constellations (星座, Seiza) are patterns formed by the locations of the stars in the observed celestial sphere, from their position relative to the observer's location in space. As such, constellations differ between locations and constellation books are only sold on the planets they are visible from. Constellations are often used in the process of navigating using the stars .
When the fabric of space is ripped by a large distortion, such as the one produced by the Golden Ghost Ship exiting subspace, large shockwaves, as large as a supernova, can be produced which travel across space .
- Main article: Subspace
Subspace is a special space apart from regular space, which exists simultaneously in parallel and has the same coordinates, but possesses different physical laws. It is primarily used for faster-than-light communication and travel. Certain distortions in one can cause disturbances in the others .