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🌌 What is AU?

AU = Astronomical Unit

1️⃣ What does AU mean?

• AU is a special unit used to measure distances in space.
• 1 AU is the distance from the Earth to the Sun.

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2️⃣ How long is 1 AU?

• 1 AU ≈ 150 million kilometers
• Scientists use AU to measure distances inside our solar system.

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3️⃣ Example using AU

• Earth to Sun = 1 AU
• Mars to Sun ≈ 1.5 AU
• Jupiter to Sun ≈ 5 AU

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🌠 What is a Light Year?

1️⃣ What does Light Year mean?

• A Light Year is not time — it is distance.
• It tells us how far light travels in one year.

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2️⃣ How fast is light?

• Light is very fast: 300,000 km per second!
• In one year, light travels a huge distance.

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3️⃣ How long is 1 Light Year?

• 1 Light Year ≈ 9.5 trillion kilometers
• It is used to measure distances between stars and galaxies.

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🌍 Easy way to remember

Unit	Used for	Example
AU	Inside solar system	Earth–Sun
Light Year	Between stars	Nearest star

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🧠 Simple memory trick

AU = Sun distances
Light Year = Star distances

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⭐ Fun fact

• Sunlight takes 8 minutes to reach Earth.
• The nearest star (after the Sun) is 4.3 light years away!

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