Galaxies and Galaxy groups


On a clear night, far away from city lights, a faint luminous band stretches across the sky — the quiet glow of our home in the universe. This is where our story begins.

A galaxy is a vast cosmic system of stars, gas, and dust, all bound together by gravity. These immense structures can contain anything from a few thousand to trillions of stars, forming the fundamental building blocks of the universe.

Our home galaxy, the Milky Way, is a barred spiral galaxy spanning roughly 100,000 light-years in diameter. Seen from above, it reveals a bright central core from which elegant spiral arms extend, winding outward into the darkness of space.

Our solar system resides quietly within one of these spiral arms, about 26,000 light-years from the galactic center — just a small part of an immense cosmic structure.

The Milky Way is not still. It slowly rotates, carrying its stars — and our Sun — along with it. Our solar system travels through space at an average speed of about 828,000 km/h, requiring roughly 230 million years to complete a single orbit around the galactic center.

But what would our galaxy look like from the side?

Since we are located within the Milky Way, capturing such a perspective directly is impossible. However, thanks to the incredibly precise measurements of more than one billion stars from the ESA Gaia mission, astronomers have been able to reconstruct a remarkably realistic view.

This reconstruction reveals our galaxy as a thin, slightly warped disk — a structure typical of many spiral galaxies. Within this disk lie our Sun and all the stars visible in the night sky.

The subtle colors in this view arise from interstellar dust, young hot blue stars, and glowing reddish emission nebulae, giving us a deeper impression of the dynamic and complex nature of our galaxy.