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What Gases Are Found in Outer Space?

Outer space consists of a huge vacuum. Through gravitational pull, planets and other astronomical bodies, like the Earth, suck out most of the gas and particles in outer space. The most dominant gases still found in the vacuum of outer space are hydrogen and helium. There are other elements present, but they tend to be labeled together into one term known as "interstellar dust."

The Interstellar Medium
- Outer space -- also known as the "interstellar medium" -- contains hydrogen, helium and interstellar dust in very small amounts. According to the University of New Hampshire Experimental Plasma Group, the average density of these particles in the interstellar medium is only "about one atom per cubic centimeter" as opposed to the air on Earth, which has "a density of approximately 30,000,000,000,000,000,000 molecules per cubic centimeter."
Hydrogen
- Hydrogen can be found anywhere in the universe, including the vast reaches of outer space. Hydrogen makes up about 75 percent of all atoms in outer space and holds one of the top spots nearby as it is the third most abundant on Earth. Hydrogen's chemical composition is also the simplest of all elements; most of the time, a hydrogen atom contains only one proton and one electron. This simplicity makes it tasteless, odorless and colorless.
Helium
- Helium makes up 24 percent of the gas present in outer space, making it the second most abundant element in outer space. This inert gas cannot exist in compound form; its simplistic structure of helium makes it the second simplest element as well, consisting only of two neutrons, two electrons and two protons. It is also tasteless, odorless and colorless. Helium has the lowest boiling point among all elements at minus 452 degrees Fahrenheit.
Interstellar Dust
- Hydrogen and helium make up the majority of gas found in outer space, but there are other trace elements present in outer space known as interstellar dust. This "dust" composition consists of several other elements and makes up less than 1 percent of all elements found in outer space. Interstellar dust differs from the dust on Earth; it is composed of very small irregular particles containing carbon, ice, iron compounds and silicates.

Astronomy