Universe

The Universe is everything that exists — all of space, time, matter, and energy. It includes stars, planets, galaxies, and even the smallest particles that make up everything around us. When you look up at the night sky and see stars shining, you are seeing only a small part of the vast Universe. It is so large that no one knows how far it truly goes, and scientists believe it may have no end at all.

Most scientists think the Universe began about 13.8 billion years ago with a giant event called the Big Bang. Before the Big Bang, everything was squeezed into an extremely small, hot, and dense point. Then, in a moment, it began to expand very quickly. As the Universe grew, it cooled, and matter started to form. Clouds of gas came together to make stars and galaxies. Over billions of years, planets like earth formed around some of these stars. Even now, the Universe keeps expanding, and the galaxies are moving farther apart every second.

The things we can see — like stars, planets, and dust — are only a small part of the Universe. Scientists have discovered that most of it is made of two invisible things called dark matter and dark energy. Dark matter holds galaxies together with its gravity, even though it cannot be seen. Dark energy seems to make the Universe expand faster and faster. Together, these mysterious parts make up about 95% of the Universe, while everything we can see makes up less than 5%.

Our own Milky Way Galaxy is just one of billions of galaxies in space. Each galaxy contains billions of stars, and many of those stars have their own systems of planets. The sun is one of these stars, and Earth is one of its eight planets. Astronomers use telescopes, satellites, and spacecraft to study space and learn more about faraway stars, black holes, and galaxies. They also look for signs of life beyond our planet, hoping to answer one of the biggest questions: are we alone in the Universe?

Scientists who study the Universe and its origins are called cosmologists. They use physics, mathematics, and observations to understand how the Universe began, how it has changed, and what its future might be. Some think the Universe will keep expanding forever, while others wonder if it might one day stop and shrink again. Although there are still many mysteries, every discovery helps us learn more about where we come from and what connects all things in space.

The Universe reminds us how small our world is, yet how amazing it can be. From the glow of distant stars to the life on our planet, everything is part of one enormous cosmic story. Studying the Universe helps us see the beauty, mystery, and wonder of the world we live in.