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How Planetary Defense Works

Interactive passage with audio narration, comprehension questions, and printable PDF.

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Format: Interactive (Online), Printable (PDF)
Grades: 5678
Subjects: scienceela
Standards: MS-ESS1-3
Languages: English, Spanish

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Reading passage

Reading comprehension

Audio narration

With word word highlighting

Comprehension quiz

Auto-graded

Writing activity

Open-ended response

Glossary & flashcards

Vocabulary practice

Differentiated version

Adapted for varied levels

Spanish translation

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About this reader

This engaging 500-word reading passage aligned with NGSS MS-ESS1-3 and MS-ESS1.B standards introduces middle school students to planetary defense systems. Students learn how scientists use telescopes to monitor near-Earth objects, calculate collision probabilities, and test deflection methods to protect Earth from asteroid and comet impacts. The passage includes real-world connections to the dinosaur extinction event and NASA's 2022 DART mission, which successfully changed an asteroid's orbit. Audio-integrated content supports diverse learners with vocabulary glossaries in English and Spanish, differentiated reading levels, and interactive activities including comprehension quizzes, writing prompts, and graphic organizers. Students explore cause-and-effect relationships in space science while developing critical thinking skills about how technology protects our planet from cosmic threats.

Written by Workybooks TeamPublished by Workybooks

Sample passage and quiz content

CONTENT PREVIEW

"Artist's illustration of NASA's Double Asteroid Redirection Test Mission" by National Aeronautics and Space Administration / Wikimedia Commons

Asteroids and comets do hit Earth. Scientists explain that a massive asteroid impact caused the extinction of the dinosaurs about 66 million years ago. Evidence shows that space rocks continue to enter our atmosphere regularly. Most burn up before reaching the ground, but larger objects can cause serious damage. This real risk is why scientists developed planetary defense systems to protect our planet.

Scientists use powerful telescopes to monitor near-Earth objects, or NEOs. These space rocks include asteroids and comets that orbit close to our planet. Telescopes scan the sky every night to detect and track these objects. When scientists discover a new NEO, they record its position and speed. They use this data to calculate the object's orbit, which is the path it follows around the Sun.

After tracking an object for several weeks or months, scientists can predict where it will travel in the future. They calculate collision probability, which measures the chance that an object might hit Earth. Most NEOs have a collision probability of nearly zero. However, scientists continue monitoring them because orbits can change slightly over time. Gravity from planets and the Sun can pull objects into different paths.

When scientists identify a potentially dangerous asteroid, they develop plans to change its course. One method is called kinetic impact. This technique involves crashing a spacecraft into an asteroid at high speed. The impact transfers energy to the asteroid and pushes it slightly off course. Even a small change in speed can make the asteroid miss Earth by a safe distance.

NASA tested this method in September 2022 with the DART mission. Scientists sent a spacecraft to crash into Dimorphos, a small asteroid orbiting a larger asteroid called Didymos. The mission succeeded in changing Dimorphos's orbit by about 33 minutes. This deflection proved that humans can alter an asteroid's path. The test showed that planetary defense technology works when we have enough warning time.

Planetary defense matters because it protects life on Earth. Scientists estimate that an asteroid larger than one kilometer across could cause global damage. Early detection gives us time to plan and launch a deflection mission. International space agencies now work together to track NEOs and share data. This cooperation helps ensure that we can respond quickly if a dangerous object heads toward Earth.

Interesting Fact: Scientists track more than 30,000 near-Earth objects, and they discover about 3,000 new ones each year. Most are small and pose no threat to our planet.

What caused the extinction of the dinosaurs about 66 million years ago?

A massive asteroid impactA volcanic eruptionClimate changeA comet that passed near Earth

What do scientists use to monitor near-Earth objects?

SatellitesTelescopesRadar systemsSpace stations

What does 'collision probability' mean in the context of planetary defense?

The size of an asteroidThe speed at which an asteroid travelsThe chance that an object might hit EarthThe distance between Earth and an asteroid

What is the term for the curved path an object follows around the Sun?

TrajectoryOrbitRouteDirection

Based on the passage, why do scientists continue monitoring NEOs even when collision probability is nearly zero?

Because telescopes need constant useBecause orbits can change slightly over timeBecause new asteroids form regularlyBecause computers make calculation errors

How does the kinetic impact method work to deflect an asteroid?

It uses explosives to break the asteroid apartIt uses gravity to pull the asteroid awayIt crashes a spacecraft into the asteroid at high speedIt uses lasers to heat and move the asteroid

What can you infer about the importance of early detection of dangerous asteroids?

It allows scientists to study asteroids more closelyIt gives enough time to plan and launch a deflection missionIt helps predict when new asteroids will formIt makes telescopes more accurate

If scientists discovered an asteroid heading toward Earth in 50 years, which planetary defense method would likely be most useful based on the passage?

Waiting to see if the orbit changes naturallyUsing kinetic impact to deflect itBuilding underground sheltersMoving Earth's orbit

True or False: The DART mission in 2022 successfully changed the orbit of the asteroid Dimorphos.

TrueFalse

True or False: Most near-Earth objects are large enough to cause global damage if they hit Earth.

TrueFalse