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Moons of the Solar System — Reading Comprehension

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MS-ESS1-2

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This comprehensive passage, designed for grades 6-8 and aligned to NGSS standard MS-ESS1-2, delves into the fascinating world of the moons in our solar system. Students will learn about the diversity of over 200 confirmed moons, including unique examples like Earth's large moon, Mars' small captured moons, and the complex systems of Jupiter and Saturn. The passage explains mechanisms of moon formation—such as co-formation, capture, and impact debris—and highlights remarkable moons like Ganymede, Titan, and Europa. Scientific vocabulary is clearly embedded and supported by a glossary. Students will also explore how scientific discoveries about moons are made, the role of tidal locking, and the potential for life beyond Earth. Multiple activities—including quizzes, writing prompts, and visual graphic organizers—support comprehension and critical thinking. Audio integration is available for all content, making this resource accessible and engaging for all learners.

CONTENT PREVIEW

"Moons of solar system v7" by Originally uploaded from NASA by Bricktop; edited by Deuar, KFP, TotoBaggins, City303, JCPagc2015 /
Source: Wikimedia Commons (Public domain).

Moons, also known as natural satellites, are objects that orbit planets throughout our solar system. Over 200 confirmed moons have been discovered so far, and new moons are found regularly as technology improves. These satellites vary greatly in size, composition, and origin. Studying moons helps scientists understand both the history of our solar system and the processes that shape planetary systems.

Formation and Diversity of Moons
Moons form in several ways. Some, like Jupiter’s four largest moons, formed from the same disk of gas and dust that created their planet—a process called co-formation. Others, such as Mars’ tiny moons Phobos and Deimos, are likely captured asteroids. Earth's moon is thought to have formed when a large object collided with Earth, and debris from this impact coalesced into a satellite. This diversity leads to a wide range of moon sizes, from Ganymede—Jupiter’s largest moon, which is even bigger than Mercury—down to moons less than 1 kilometer across. Most moons are much smaller than their planets, but Earth’s Moon is unusually large compared to Earth, making it an interesting case for scientists.

Systems and Interactions
Moons interact with their planets and each other in complex ways. Many moons are tidally locked, meaning the same side always faces their planet due to gravitational forces. For example, our Moon is tidally locked to Earth, which is why we always see the same side. Some moons, like Jupiter’s Io, experience intense tidal forces that create volcanic activity, making Io the most volcanically active body in the solar system. Others, like Europa and Saturn’s Enceladus, have subsurface oceans beneath icy crusts. These oceans may harbor the conditions needed for life. Saturn’s Titan stands out for its thick atmosphere and lakes of liquid methane, making it one of the most Earth-like places in the solar system, even though its chemistry is very different.

Scientific Discoveries and Future Exploration
Advances in telescopes and spacecraft have allowed scientists to discover new moons and study their features in detail. For instance, Ganymede’s magnetic field was detected by spacecraft, and geysers erupting from Enceladus were observed by NASA’s Cassini mission. The number of moons can change as new satellites are found; for example, Jupiter is now known to have over 95 moons, while Saturn has more than 140. Future missions aim to explore ocean worlds like Europa and Enceladus to search for signs of life and better understand how moons form and evolve. The study of moons helps scientists answer broader questions about planetary systems, habitability, and the origins of the solar system itself.

Interesting Fact: Some moons, like Neptune’s Triton, orbit in the opposite direction of their planet’s rotation. This retrograde motion suggests they were captured from elsewhere in the solar system.

How many confirmed moons are there in our solar system according to the passage?

Over 200About 50Exactly 100Less than 20

Which moon is the largest in the solar system?

TitanGanymedeEuropaEarth's Moon

What does 'tidally locked' mean as used in the passage?

A moon that moves very fastA moon that always shows the same side to its planetA moon made of iceA moon that was formed from impact debris

Which planet’s moon has lakes of liquid methane?

MarsNeptuneSaturnJupiter

What is the likely origin of Mars’ moons Phobos and Deimos?

Formed with Mars in co-formationCaptured asteroidsImpact debrisCreated by volcanic activity

What is 'retrograde motion' as described in the passage?

When a moon orbits faster than its planet spinsWhen a moon orbits in the opposite direction of the planet's rotationWhen a moon is made of iceWhen a moon has a thick atmosphere

Why are moons like Europa and Enceladus important for scientists searching for life?

They are close to the SunThey have subsurface oceans that might have lifeThey are the largest moonsThey have strong magnetic fields

Which of the following is TRUE based on the passage?

All moons are smaller than MercuryMoons can form in multiple ways, including from impact debrisAll moons have thick atmospheresOnly Jupiter has more than 50 moons

Most moons are tidally locked to their planet. (True/False)

TrueFalse

Earth’s Moon is unusually large compared to its planet. (True/False)

TrueFalse