What Is the Milky Way Galaxy？

Are you looking for an easy way to teach your child about space? We’ve put together a set of free materials that parents and teachers can use right away. In this lesson, your child will dive into the fascinating world of the Milky Way Galaxy.

We’ll explore the structure and composition of our home galaxy, the Milky Way. Explore science in a more engaging way with captivating 3D videos and interactive quizzes. Download our app to get started!

What You Will Learn From This Lesson

The Milky Way Galaxy is a spiral galaxy that contains hundreds of billions of stars. When viewed from one perspective, it resembles a large whirlpool. The Solar System, which includes our Sun and Earth, is located within the Milky Way. Our location is near the edge of the galaxy, which can be thought of as the suburbs of a big city.

What Shape Is the Milky Way?

The Milky Way Galaxy is a barred spiral galaxy because many stars gather at the center, forming a bar-shaped structure. The structure of the Milky Way is composed of three main parts: the galactic bulge, the galactic disk, and the galactic halo.

• The galactic bulge is the bright, central area that consists of many stars.
• The galactic disk is an enormous, wide, flattened structure where the spiral arms are located, giving it a potato chip-like appearance when viewed from the side. The disk is about 200 thousand light-years across. A light-year is a unit of astronomical distance equal to the distance light travels in one year, which is approximately 9.5 trillion kilometers (6 trillion miles).
• The galactic halo surrounds the galactic disk, is shaped like a sphere, and is scattered with stars. Within the halo, many stars cluster together into a ball-shaped structure called a globular cluster.

What Is the Milky Way Composed Of?

The Milky Way is composed of stars, dust, gas, and dark matter. Together, the stars, gas, and dust make up only a small part of the galaxy. The majority of the Milky Way is made up of dark matter, which is invisible. Everything within the Milky Way, including these components, orbits the Galactic Center.

What Is at the Center of the Galaxy?

At the center of the Milky Way, within the Galactic Bulge, is the Galactic Center. At the exact center is a black hole that everything in the galaxy orbits. A black hole is a celestial body with such a strong gravitational pull that nothing, not even light, can escape it. This extreme gravity makes it impossible to see directly. Scientists recently captured a picture of the black hole at the center of our Milky Way using eight radio telescopes.

Fun Fact

• The Solar System has orbited the Galactic Center more than 20 times already.
• One light-year is about 9.5 trillion kilometers (6 trillion miles).
• The vast majority, or 90%, of the Milky Way is invisible dark matter

Vocabulary

• Milky Way Galaxy: A big, spiral-shaped group of hundreds of billions of stars, including our own sun and Earth.
• Spiral Galaxy: A type of galaxy, like the Milky Way, that has a flat, spinning disc and a central clump of stars, often with arms that curve out.
• Galactic Disk: The main, wide, and flat part of the Milky Way where the spiral arms are found. Our Solar System is located here.
• Galactic Bulge: The bright, bar-shaped center of the galaxy that is packed with many stars.
• Galactic Halo: A huge, ball-shaped area of stars that surrounds the galactic disk and bulge. The stars here are spread out far apart.
• Light-year: A unit used to measure very long distances in space. It is the distance light travels in one whole year.
• Dark Matter: A substance in space that is invisible and makes up most of the Milky Way galaxy.
• Black Hole: A spot in space with gravity so strong that nothing, not even light, can escape it. This is why it cannot be seen directly.