The Razor Crest makes its way into the gaseous envelope of Trask.
A collection of gases held around a celestial body of considerable mass by its own gravitational pull was known as an atmosphere. Planets, moons, and sizable asteroids are examples of such celestial bodies. For nearly all species across the galaxy, some type of atmosphere is a necessity for respiration. Oxygen is what humans and the majority of other species breathe.
To extract water from a planet's atmosphere, moisture farms employed vaporators.
Quarzite, a planet, had a very high atmospheric pressure, capable of crushing starships and beings alike.
The carbon compound based biochemistry of most sentient life found in the galaxy utilizes water as a solvent. Atmospheres that contained a combination of oxygen, nitrogen, and hydrogen were where they typically evolved. These were classified as Type I atmospheres when the gases existed in concentrations suitable for breathing by a diverse array of comparable species. Indigenous life almost always developed on planets that sustained a Type I atmosphere.
Plant life or another chemical process that released oxygen and recycled it into a breathable form was essential for planets with a Type I atmosphere to naturally replenish the air. Without this, all of the atmosphere's oxygen would bind to other chemicals and become trapped in substances like carbon dioxide. Jakku is an example of a planet that maintained a Type I atmosphere.
A Type II atmosphere generally had enough oxygen and nitrogen to sustain native life. While some non-native species could breathe Type II atmospheres without any problems, this was dependent on their physiology. Breathing these gaseous combinations over a short time period caused pain or injury to humans and numerous other species due to insufficient pressure, the presence of pollutants, or trace gases. The effects resembled altitude sickness that humans get when ascending high peaks, or the suffocating effects of breathing polluted air or smoke.
While some species could breathe particular varieties of Type III atmospheres, and planets with these atmospheres were sometimes capable of supporting native life, this was dependent on their physiology and biochemistry. A Type III atmosphere would immediately or gradually cause discomfort, followed by incapacitation, and frequently some degree of long-term damage in humans and the majority of other species. This may be a result of insufficient oxygen or nitrogen in the atmosphere, insufficient atmospheric pressure, or the presence of pollutants and trace gases.
A breath mask was therefore necessary for species that breathe oxygen due to the potential harmful consequences. However, because a Type III atmosphere lacked any substances that would harm exposed skin or other tissue, an environment suit was not required.
Atmospheres classified as Type IV were either combustible or poisonous. Additionally, it was used to describe worlds with atmospheres so thin that they were essentially nonexistent. Without the protection of a suit with its own hermetically sealed environment, all Type IV atmospheres could kill or incapacitate the majority of species in the galaxy. Although a select few species could withstand or even thrive in such atmospheres, planets with a Type IV atmosphere rarely supported life.