The band that looks like milk in the night sky isn't actually milk, of course–it's a galaxy. A galaxy is a huge cluster of stars, dust, gas, and other objects bound together in space. Our Solar System, which includes the sun, Earth, and other planets, is part of the Milky Way galaxy. The Milky Way is about 14 billion years old. Almost 10 billion years older than our Solar System! It took many years to discover the Milky Way. In the early 1500s, Nicolaus Copernicus was the first to show that Earth was an object orbiting the Sun. In the early 1600s, Galileo Galilei used a basic telescope to show that the Milky Way was made up of countless stars. Then, in the late 1700s, William Herschel tried to map out the shape of the Milky Way. He did not realize that large portions of the galaxy were hidden by gas and dust, so he could not identify the true shape. Edwin Hubble had access to many powerful telescopes and tools to observe more objects in space. His work provided evidence that the Milky Way was only one of many galaxies in the universe. He also identified the spiral shape of our galaxy.

Why was Herschel unable to correctly map out the shape of the Milky Way?

He couldn't calculate the actual age of the Milky Way galaxy.
He couldn't see through the Milky Way's gas and dust particles.
He didn't know that the Earth and sun are part of the galaxy.
He didn't know that the Milky Way was made up of many stars.