Local Group facts for kids
The Local Group is a cluster of galaxies – that means a group of galaxies bound together by gravity. It's not just a random collection; these galaxies are all relatively close to each other compared to other galaxies in the universe. Think of it like a small town in a vast, sprawling country. Our own Milky Way galaxy is just one member of this amazing galactic community!
The term "Local Group" was introduced by Edwin Hubble in 1936.
Contents
How big is the Local Group?
The group has more than 50 galaxies (including dwarf galaxies) with a total mass of about (1.29 ± 0.14)×1012Ms. The galaxies of the Local Group cover a 10 million light-year diameter. That's a seriously long distance! To give you an idea, a light-year is the distance light travels in one year – and light travels incredibly fast! It would take a super-fast spaceship many, many years to travel across the Local Group.
The group itself is part of the Virgo Supercluster (also called the Local Supercluster).
The main galaxies
The Local Group isn't just a couple of galaxies; it's a bustling community with dozens of galaxies of different shapes and sizes. But some galaxies are much bigger and brighter than others. Let's meet the superstars:
- The Milky Way: Our home galaxy! A beautiful spiral galaxy with hundreds of billions of stars, including our Sun. It's about 100,000 light-years across.
- Andromeda (M31): The largest galaxy in the Local Group. It's also a spiral galaxy, even bigger and brighter than the Milky Way! It’s about 2.5 million light-years away from us and is visible on a clear night with the naked eye, appearing as a fuzzy patch of light.
- Triangulum (M33): This is a smaller spiral galaxy, a sort of "little brother" to the Milky Way and Andromeda. It’s about 3 million light-years away from us.
These three are the biggest and brightest, but there are many, many more!
The dwarfs
Besides these giant spiral galaxies, the Local Group is home to many smaller galaxies called dwarf galaxies. These are much smaller than the Milky Way, Andromeda, and Triangulum. They are often irregular in shape and contain significantly fewer stars. Think of them as the smaller houses and apartments nestled around the bigger buildings.
Some examples of dwarf galaxies in the Local Group include:
• Large Magellanic Cloud (LMC): A satellite galaxy of the Milky Way. "Satellite" means it orbits our galaxy. It’s a relatively large dwarf galaxy, visible in the Southern Hemisphere.
• Small Magellanic Cloud (SMC): Another satellite galaxy of the Milky Way, also visible in the Southern Hemisphere. It's smaller than the LMC.
• Canis Major Dwarf Galaxy: This is actually the closest galaxy to the Milky Way! It’s partially hidden behind the bright stars of our own galaxy.
There are many other dwarf galaxies – astronomers keep discovering new ones! They are important because they offer clues to how galaxies form and evolve.
How do we know about the Local Group?
Astronomers use powerful telescopes on Earth and in space to study the Local Group. These telescopes allow us to see the light from these distant galaxies, and by studying that light, we can learn a lot about their properties: how far away they are, how fast they are moving, and what they are made of.
The future of the Local Group
The galaxies in the Local Group are not standing still! They are all moving, influenced by each other's gravity.
In about 4.5 billion years, the Milky Way and Andromeda are expected to collide! Don’t worry, this won't be a catastrophic crash like billiard balls; the galaxies are mostly empty space. Instead, it will be a slow, majestic merger, eventually forming a single, giant elliptical galaxy. This future giant galaxy is sometimes called "Milkomeda."
The Local Group is a fascinating area of study for astronomers. By studying the galaxies within it, we learn about the formation and evolution of galaxies in general. It's our cosmic backyard, and there's still so much to discover!
Map
Related pages
See also
In Spanish: Grupo Local para niños
