On a clear night in the country, you can look into the sky and see a soft band of light stretching overhead. That glowing band is the starry disk of our galaxy-the Milky Way-seen edge-on from within. Yet this entire cosmic panorama, as vast as it might seem, represents a very small part of our galaxy.

Our galaxy is often called the Milky Way, but this hazy glow also has many other names. The Blackfoot people of the North American Plains call it the Wolf Trail, after the wolves that taught them how to hunt together.

Some Indigenous Australians see the Milky Way as a river in the sky, with the big stars as fish, and the small ones as lily bulbs.

The name Milky Way comes from the ancient Greeks, who thought the galaxy looked like the milk of the goddess Hera flowing across the sky.

The term "galaxy" comes from the Greek word "galaktos," which means milk.

It should come as no surprise that the term "galaxy" comes from the Greek word "galaktos," which means milk.
On a clear night in the country, you can look into the sky and see a soft band of light stretching overhead. That glowing band is the starry disk of our galaxy-the Milky Way-seen edge-on from within. Yet this entire cosmic panorama, as vast as it might seem, represents a very small part of our galaxy.

Our galaxy is often called the Milky Way, but this hazy glow also has many other names. The Blackfoot people of the North American Plains call it the Wolf Trail, after the wolves that taught them how to hunt together.

Some Indigenous Australians see the Milky Way as a river in the sky, with the big stars as fish, and the small ones as lily bulbs.

The name Milky Way comes from the ancient Greeks, who thought the galaxy looked like the milk of the goddess Hera flowing across the sky.

The term "galaxy" comes from the Greek word "galaktos," which means milk.

It should come as no surprise that the term "galaxy" comes from the Greek word "galaktos," which means milk.

© Canadian Heritage Information Network, 2003

Watch a video about the Milky Way

One of the most spectacular sights on a clear dark night is the band of light called the Milky Way that sweeps across our sky. As spectacular as this view is, it represents only a small portion of the nearly 200 billion stars estimated to make up our galactic homeland. If we could look down on our galaxy from a distance of about 30 million light years it might look like look this Gemini image of the spiral Galaxy called M74 in the constellation of Pisces. If this were our galaxy, our sun would be located about two-thirds of the way out from the center in a region called the Perseus arm.

Canadian Heritage Information Network

© Canadian Heritage Information Network, 2003.


Astronomers now believe that the Milky Way is a barred spiral galaxy about 100 000 light-years in diameter. It’s home to nearly 200 billion stars and their planets. The Milky Way has three parts: a disk, in which our solar system resides, a central bulge in the middle, and a spherical halo that surrounds the whole galaxy.

Astronomers now believe that the Milky Way is a barred spiral galaxy about 100 000 light-years in diameter. It’s home to nearly 200 billion stars and their planets. The Milky Way has three parts: a disk, in which our solar system resides, a central bulge in the middle, and a spherical halo that surrounds the whole galaxy.

© Canadian Heritage Information Network, 2003

Spiral Galaxy M83

If you could see the Milky Way from 10 million light-years away, it would closely resemble the spiral galaxy M83.

Bill Schoering / NOAO / AURA / NSF

© Bill Schoering / NOAO / AURA / NSF


The Milky Way’s disk contains large clouds of interstellar dust and gas, which clump together into pinkish, star-forming regions. These, in turn, replenish the spiral arms with fresh groups of hot, young blue stars, known as open clusters. The disk’s bluish color comes from the young stars in the spiral arms. The Milky Way has hundreds of star-forming regions, and about 1 500 known open clusters.

The Milky Way’s disk contains large clouds of interstellar dust and gas, which clump together into pinkish, star-forming regions. These, in turn, replenish the spiral arms with fresh groups of hot, young blue stars, known as open clusters. The disk’s bluish color comes from the young stars in the spiral arms. The Milky Way has hundreds of star-forming regions, and about 1 500 known open clusters.

© Canadian Heritage Information Network, 2003

Young Stars

Young stars become visible as their radiation blows dust and gas away from the centre of the Rosetta Nebula.

Canada-France-Hawaii Telescope

© CFHT


We’re inside our galaxy, so it’s hard for us to get a good look at it. Also, all the interstellar dust and gas obscures our view along the plane of the galaxy, which makes it hard to see its exact shape. But modern instruments using radio waves have penetrated the haze, revealing many astounding features.

For one thing, the Milky Way is not the quiet galaxy we once imagined. Intense X-rays and plumes of gamma radiation blaze from its core, where stars whip around a central black hole at over 900 km/s. That’s fast enough to circle the Earth in 45 seconds.

Also, the Milky Way is consuming several of its smaller neighbour galaxies. In fact, we’re in mid-collision with one of them. The Sagittarius dwarf, a spherical galaxy, is currently embedded in the Milky Way’s disk, just 80 000 light-years from Earth, on the far side of the central bulge. Two nearby irregular galaxies, the Large and Small Magellanic clouds, are being gravitationally consumed as the Milky Way tears streamers of dust and gas away from them.
We’re inside our galaxy, so it’s hard for us to get a good look at it. Also, all the interstellar dust and gas obscures our view along the plane of the galaxy, which makes it hard to see its exact shape. But modern instruments using radio waves have penetrated the haze, revealing many astounding features.

For one thing, the Milky Way is not the quiet galaxy we once imagined. Intense X-rays and plumes of gamma radiation blaze from its core, where stars whip around a central black hole at over 900 km/s. That’s fast enough to circle the Earth in 45 seconds.

Also, the Milky Way is consuming several of its smaller neighbour galaxies. In fact, we’re in mid-collision with one of them. The Sagittarius dwarf, a spherical galaxy, is currently embedded in the Milky Way’s disk, just 80 000 light-years from Earth, on the far side of the central bulge. Two nearby irregular galaxies, the Large and Small Magellanic clouds, are being gravitationally consumed as the Milky Way tears streamers of dust and gas away from them.

© Canadian Heritage Information Network, 2003

Learning Objectives

The learner will:

  • Define “Milky Way”, and describe its features
  • Appreciate our place in the universe

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