Nucleus facts for kids

A nucleus (pronounced NEW-klee-us) is like the central part or core of something. Think of it as the very heart or control center. Just like the pit of a peach is its nucleus, this word is used in science to describe important central parts of many different things.

What is a Nucleus?

The word "nucleus" comes from a Latin word meaning "kernel" or "little nut." In science, it usually refers to the most important or central part of an object or system. It's often where the main activity or control happens.

The Cell's Control Center: The Cell Nucleus

In biology, the cell nucleus is a very important part found in most living cells, like those in your body, plants, and fungi. It's like the brain or control center of the cell.

What it Does

The cell nucleus holds all the genetic information (DNA) that tells the cell what to do and how to grow, divide, and function. It controls everything from making proteins to deciding when the cell should make copies of itself. Without a nucleus, most cells wouldn't be able to survive or work properly.

Inside the Nucleus

Inside the nucleus, the DNA is organized into structures called chromosomes. These chromosomes contain all the instructions for building and operating an organism. The nucleus also has a smaller, dense area called the nucleolus, which helps make ribosomes—tiny factories that build proteins.

The Heart of an Atom: The Atomic Nucleus

In physics and chemistry, the atomic nucleus is the tiny, dense center of an atom. Atoms are the basic building blocks of everything around us, from the air we breathe to the chairs we sit on.

What it's Made Of

The atomic nucleus is made up of two types of tiny particles: protons and neutrons. Protons have a positive electrical charge, and neutrons have no charge (they are neutral). These particles are held together by a very strong force. Around this nucleus, much lighter particles called electrons orbit, carrying a negative charge.

Why it Matters

The number of protons in an atom's nucleus determines what element it is. For example, an atom with one proton is always hydrogen, and an atom with six protons is always carbon. The nucleus is also where nuclear energy comes from, like the energy used in power plants or released by the Sun.

The Icy Core of a Comet: The Comet Nucleus

In astronomy, the comet nucleus is the solid, central part of a comet. Comets are like cosmic snowballs that orbit the Sun.

What Comets Are

Comets are small, icy bodies that travel through space. When they get close to the Sun, the ice and dust on their surface heat up and turn into gas, creating a glowing "coma" (a fuzzy atmosphere) and often a long, bright tail that we can see from Earth.

The Comet's "Dirty Snowball" Core

The comet nucleus is often called a "dirty snowball" because it's a mix of ice (like water ice, carbon dioxide ice, and methane ice) and dust particles. This icy core is usually only a few kilometers (a few miles) wide, but it's the source of all the gas and dust that makes a comet visible. As the comet travels around the Sun, the nucleus slowly loses its material, making the comet shrink over time.