Our home galaxy, the Milky Way, is a magnificent spiral galaxy with a disc of stars spanning over 100,000 light-years, according to NASA reports. Earth is located within one of its spiral arms, about halfway from the galactic centre, and our solar system takes roughly 240 million years to complete a single orbit around it. From our vantage point on Earth, the Milky Way appears as a faint, milky band stretching across the night sky, a feature that inspired its name. The galaxy is part of the Local Group, a collection of more than 50 galaxies, ranging from tiny dwarf galaxies to the massive Andromeda Galaxy. This Local Group itself is a component of the enormous Laniakea supercluster, a vast network of galaxies spanning hundreds of millions of light-years.
From stars to black holes: Things you didn’t know about Milky Way
The Milky Way is a spiral galaxy and our cosmic home, containing hundreds of billions of stars, including the Sun. From Earth, it looks like a faint, milky band across the night sky. At its centre lies a supermassive black hole, and it is part of the Local Group of galaxies, according to NASA.1. The Milky Way is warped
Source: NASA
The Milky Way is shaped like a giant disc, roughly 120,000 light-years across, with a central bulge about 12,000 light-years wide. It is not completely flat; instead, it is slightly warped. This warping happens because of gravitational pulls from nearby galaxies, especially the Large and Small Magellanic Clouds. Think of it like stretching and pulling on a trampoline, these nearby galaxies tug at the Milky Way, bending its edges. This makes our galaxy look a bit twisted rather than perfectly smooth, a feature shared with some other spiral galaxies in the Universe.2. It has an invisible halo
Source: NASA
Around the Milky Way is an invisible halo made mostly of dark matter, which cannot be seen through telescopes or cameras. Dark matter makes up about 90% of the galaxy, while visible matter like stars, gas, and dust makes up the remaining 10%. This invisible halo is very important because it keeps stars moving fast enough to stay in orbit around the galaxy. Without dark matter, stars, especially those far from the centre, would drift away into space. Scientists study the halo by observing the movement of stars and gas.3. The galaxy has over 200 billion starsThe Milky Way is home to over 200 billion stars, ranging from tiny, dim red dwarfs to massive, bright blue stars. Our Sun is just one of these stars. Despite its size, the Milky Way is considered a medium-sized galaxy. For comparison, the largest galaxy known, IC 1101, contains more than 100 trillion stars, almost 500 times more than the Milky Way! Each star in our galaxy has its own system of planets, moons, and other celestial bodies, making the Milky Way incredibly full of potential worlds.4. Dusty and gassy
Source: NASA
About 10-15% of the Milky Way’s visible matter is made of gas and dust, while the rest is stars. The dust is very fine, like tiny grains of sand, and spreads throughout the galaxy. When we look at the night sky, especially far from city lights, we can sometimes see the Milky Way as a faint, milky band. This band is made mostly of stars and dust packed so closely together that they look like a soft glow. The dust and gas are also important because they form new stars and planets.5. It was formed from other galaxies
Source: NASA
The Milky Way did not form alone, it grew by merging with smaller galaxies over billions of years. When a smaller galaxy collides or is absorbed, its stars and gas become part of the Milky Way. Right now, the galaxy is pulling in the Canis Major Dwarf Galaxy, adding its stars to our spiral arms. These mergers are normal in the Universe and help the Milky Way grow bigger, create new stars, and change its shape over time.6. We cannot photograph the entire galaxy
Source: NASA Science
Even though we live inside the Milky Way, we cannot take a picture of the whole galaxy. Our solar system is about 26,000 light-years from the galactic centre, so we only see a small part of it from the inside. Any pictures you have seen of the Milky Way as a full spiral are either artist’s drawings or images of other similar galaxies. Scientists use telescopes and computer models to imagine what the Milky Way looks like as a whole.7. A supermassive black hole resides at the centre
Source: NASA
At the very centre of the Milky Way is a supermassive black hole called Sagittarius A*. It is enormous, about 14 million miles across, and has a mass roughly 4 million times that of our Sun. Around it is a dense disc of gas and stars, and the black hole’s gravity keeps the galaxy’s central stars moving. Supermassive black holes like this are found at the centres of many large galaxies and play a key role in their formation and evolution.8. Almost as old as the universeThe Milky Way is extremely old. Scientists estimate it is about 13.6 billion years old, while the Universe itself is around 13.7 billion years old. This means the Milky Way formed shortly after the Big Bang. Its main parts, like the central bulge and halo, formed early, but the disc and spiral arms took shape 10–12 billion years ago. Studying the galaxy’s age helps scientists understand how galaxies grow and evolve over billions of years.9. Part of the Virgo Supercluster
Source: NASA Science
The Milky Way is not alone in space. It is part of the Virgo Supercluster, which contains at least 100 galaxy groups and clusters and spans roughly 110 million light-years. This supercluster is itself part of a larger structure called Laniakea, which links together thousands of galaxies. Being part of these massive cosmic structures shows that galaxies are connected on a huge scale, forming the intricate web of the Universe.10. The Milky Way is constantly movingThe Milky Way is not stationary; it is moving through space at an incredible speed. Together with the Local Group of galaxies, it travels at about 600 km/s (2.2 million km/h). Scientists measure this motion using the Cosmic Microwave Background, the faint radiation left over from the Big Bang. Even though we cannot feel it, this motion means the galaxy is constantly changing its position and orientation in the Universe.Also read | NASA discovers new shape of the solar system’s bubble: Not a comet, but a croissant