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How big is the Local Group?

The Local Group is 95 zettameters

Introduction: The Grandeur of the Local Group

Have you ever looked up at the night sky and wondered how vast the universe is? Did you know that our very own Milky Way is a part of an even larger group of galaxies known as the Local Group? This group is an interesting and expansive neighborhood of galaxies in the cosmos, and it’s much larger than you might think! Let’s embark on a journey to explore the size and scale of this fascinating cosmic assembly.

What is the Local Group?

The Local Group is a collection of galaxies that includes our home galaxy, the Milky Way. It’s like a big cosmic family, with many members, including dwarf galaxies and larger ones like the Andromeda Galaxy. Just as people and their belongings fill up a house, galaxies and their stars fill up the Local Group. The Local Group is shaped like a dumbbell, with two main collections of galaxies at each end. One lobe consists of the Milky Way and its satellite galaxies, and the other lobe is made up of the Andromeda Galaxy and its satellites. These two lobes are separated by a considerable distance and are slowly moving towards each other.

Size of the Local Group

The Local Group’s size is absolutely mind-boggling, especially when compared to things we’re familiar with. Its total diameter is approximately 3 megaparsecs. Now, if you’re wondering what a megaparsec is, it’s a unit of length used in astronomy, and it’s equal to a whopping 1 million parsecs or 3.26 million light-years. In simpler terms, if you were traveling at the speed of light (which is the fastest speed possible), it would take you 10 million years to go from one end of the Local Group to the other. That’s a whole lot of space! To give you a better idea, let’s compare the Local Group’s size to something we all know - the Sun. The Sun’s diameter is approximately 1.4 million kilometers. If you lined up Suns side by side, you would need about 64 quadrillion (that’s 64 followed by 15 zeros!) Suns to span the width of the Local Group. Isn’t that incredible?

The Mass of the Local Group

The size of the Local Group is not only impressive in terms of its length but also its mass. The total mass of the Local Group is around 2×10^12 solar masses. This means that the Local Group weighs as much as 2 trillion Suns! That’s heavier than you can possibly imagine.

The Local Group’s Place in the Universe

The Local Group, despite its grand size, is just a small part of an even bigger cosmic structure. It is a member of the Virgo Supercluster, a massive group of galaxies that could be a part of the even larger Laniakea Supercluster.

Interesting Facts About the Local Group

  • The Local Group has at least 80 known members, but there could be more that are hidden behind the Milky Way. - The two major galaxies in the Local Group, the Milky Way and Andromeda, are moving towards each other at a speed of 123 km/s. That’s faster than any car or airplane can travel! - The Local Group is home to a variety of galaxies, from vast spirals like the Milky Way and Andromeda to smaller dwarf galaxies. The Local Group is a fascinating part of the cosmos, offering us a glimpse into the vastness of the universe. Its size and scale are a testament to the incredible complexity and grandeur of the cosmos. So, the next time you look up at the night sky, remember that you’re a part of this amazing cosmic neighborhood!
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Abell 2029
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IC 1101
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