Volatiles facts for kids

In planetary science, volatiles are special chemical ingredients that turn into gas very easily. Think of them as the "easy-to-evaporate" stuff! They are elements and compounds that have a low boiling point. This means they don't need much heat to change from a liquid or solid into a gas.

You can often find volatiles in the crust or the atmosphere of a planet or moon. Common examples include nitrogen, water, and ammonia.

What Are Volatiles?

Volatiles are chemicals that have a low boiling point. This means they can change into a gas at relatively cool temperatures. For example, water boils at 100 degrees Celsius (212 degrees Fahrenheit) on Earth, but other volatiles like methane or carbon dioxide can boil at much colder temperatures.

• Water (H₂O): The most famous volatile, essential for life.
• Carbon Dioxide (CO₂): The gas we breathe out, and a big part of Mars's atmosphere.
• Methane (CH₄): A gas found on giant planets like Jupiter and Saturn.
• Ammonia (NH₃): Another gas, also found on icy moons and gas giants.
• Nitrogen (N₂): The main gas in Earth's atmosphere.

These are different from "refractory" materials, which have very high boiling points. Refractory materials are things like rocks and metals, which stay solid even when it's very hot.

Where Do We Find Volatiles?

Volatiles are found all over our Solar System, but their location depends on how close they are to the Sun.

In the Inner Solar System

Planets like Earth, Mars, and Venus are in the inner, warmer part of the Solar System.

• Earth: We have lots of water in our oceans, ice caps, and as vapor in the atmosphere. Nitrogen and oxygen make up most of our air.
• Mars: Mars has a thin atmosphere mostly of carbon dioxide. It also has water ice at its poles and possibly under its surface.
• Venus: Venus has a very thick atmosphere of carbon dioxide, making it super hot.

In the Outer Solar System

Further from the Sun, it's much colder. This means volatiles can stay frozen as ice.

• Gas Giants: Planets like Jupiter, Saturn, Uranus, and Neptune are mostly made of gases like hydrogen, helium, methane, and ammonia. These are all volatiles!
• Icy Moons: Many moons orbiting the gas giants, like Europa (around Jupiter) or Enceladus (around Saturn), are covered in thick layers of water ice. Some even have oceans of liquid water under their icy crusts.
• Comets: These "dirty snowballs" are mostly made of frozen volatiles like water ice, carbon dioxide ice, and methane ice. When they get close to the Sun, these ices turn into gas, creating the comet's tail.

Why Are Volatiles Important?

Volatiles play a huge role in how planets form and change.

For Life

Water is the most important volatile for life as we know it. All living things need water to survive. The presence of liquid water on Earth is a key reason why life could develop here.

For Planetary Formation

When the Solar System was forming, the inner parts were hot, so most volatiles stayed as gas or were pushed outwards. In the colder outer parts, volatiles froze into ice. This is why the inner planets are rocky, and the outer planets are gas giants or icy worlds.

For Planetary Activity

Volatiles can also affect a planet's geology. For example, water inside Earth's crust can help rocks melt, leading to volcanic eruptions. Volatiles escaping from a planet's interior can also create and replenish its atmosphere.