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What is a Globular Cluster? — Reading Comprehension

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This passage explores what a globular cluster is, focusing on their characteristics, formation, and the powerful role of gravity in holding them together. Students will learn about these ancient, dense groups of stars, often found in the halos of galaxies like the Milky Way. The content aligns with NGSS MS-ESS1-2, helping students develop and use a model to describe the role of gravity in the motions within galaxies. This engaging reading material, complete with relevant SEO keywords, is audio-integrated to enhance accessibility and learning for Grade 6 students. Activities include comprehension questions, a glossary, and short answer prompts.

CONTENT PREVIEW

Dense star cluster glowing in space, with gravity visualized and child observing through telescope. — Globular cluster held by gravity, viewed from Earth by a curious young stargazer.

Have you ever looked up at the night sky and wondered about the incredible things out there? Beyond our own solar system, there are countless wonders, and one of the most fascinating is a globular cluster. Imagine a giant, sparkling ball made of hundreds of thousands, or even millions, of stars! That's essentially what a globular cluster is.

These amazing structures are very old, often as old as the galaxy they belong to. For example, our own Milky Way galaxy has about 150 known globular clusters! They are usually found in the outer regions, or halo, of a galaxy, rather than in the flat, spinning disk where our Sun is located. Globular clusters are extremely dense, meaning the stars inside them are packed very closely together. If you lived on a planet in a globular cluster, the night sky would be filled with many more bright stars than what we see from Earth!

So, what holds all these stars together in such a tight ball? The answer is gravity. Gravity is a natural force that pulls objects toward each other. The more mass an object has, the stronger its gravitational pull. In a globular cluster, the combined gravity of all the millions of stars is incredibly strong. This powerful gravitational force keeps the cluster in its spherical shape and prevents the stars from drifting away into space. It's like a cosmic tug-of-war where gravity wins, keeping everything neatly bundled up.

Globular clusters are an important part of understanding the universe. Scientists study them to learn more about how galaxies form and evolve over billions of years. Because these clusters are so old, they give us clues about the early universe. Each star within a globular cluster is constantly moving, but gravity ensures they all stay bound together, swirling and orbiting within their communal home. These stellar cities are truly incredible examples of gravity's powerful role in the cosmos.

Interesting Fact: Some globular clusters contain a type of star called a "blue straggler" that appears younger than its neighbors, baffling astronomers!

What is a globular cluster?

A single, very bright starA dense ball of starsA type of planetA large comet

Where are globular clusters usually found in a galaxy?

In the very centerIn the flat, spinning diskIn the outer haloOutside the galaxy

What force holds a globular cluster together?

Electromagnetic forceWindGravityMagnetic fields

Why are globular clusters important for scientists?

They create new starsThey hide alien lifeClues about early universeThey are the brightest objects

The Milky Way galaxy has only a few globular clusters. True or False?

TrueFalse

If you lived in a globular cluster, what would the night sky look like?

Darker than EarthFewer visible starsFilled with more bright starsAlways daytime