🔬 ScienceGrade 3Lesson 16
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Solar System Basics

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Learning Objectives

  • 1Name the eight planets of the solar system in order from the Sun
  • 2State one key fact about each planet
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Mini Lesson

Our solar system consists of the Sun at its center and eight planets that orbit (travel around) it. Each planet is different in size, composition, and distance from the Sun. The four inner planets are rocky, while the four outer planets are much larger and made mostly of gas or ice.

The Eight Planets in Order from the Sun

  1. Mercury — the smallest planet and closest to the Sun; temperatures are extreme.
  2. Venus — the hottest planet due to a thick atmosphere that traps heat.
  3. Earth — our home; the only planet known to support life, with liquid water.
  4. Mars — called the Red Planet because of its reddish iron-oxide surface.
  5. Jupiter — the largest planet; has a massive storm called the Great Red Spot.
  6. Saturn — known for its beautiful rings made of ice and rock.
  7. Uranus — an ice giant that rotates on its side.
  8. Neptune — the farthest planet from the Sun; has the strongest winds in the solar system.

Key Facts About the Solar System

  • The Sun is a star at the center of our solar system — not a planet.
  • Planets travel around the Sun in paths called orbits.
  • The closer a planet is to the Sun, the shorter its year (one orbit).
  • A moon is a natural object that orbits a planet. Earth has one Moon; Jupiter has over 90.
Inner planets of the solar systemThe Sun and inner four planets: Mercury, Venus, Earth, and Mars shown with orbit rings.Inner PlanetsSunMercuryClosestVenusHottestEarthHas lifeMarsRed planetRocky inner planets (1-4)
Outer planets of the solar systemOuter four planets: Jupiter, Saturn (with rings), Uranus, and Neptune in a table.Outer PlanetsJupiterLargest planet; Great Red SpotSaturnBeautiful rings of ice and rockUranusIce giant; rotates on its sideNeptuneFarthest; strongest windsGas giants and ice giants (5-8)
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Memory trick to remember the order: "My Very Excellent Mother Just Served Us Nachos" — Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.

Vocabulary
Solar system
The Sun and all the objects that travel around ite.g. Our solar system has eight planets.
Planet
A large round object that travels around a stare.g. Jupiter is the largest planet in our solar system.
Orbit
The path one object follows as it travels around anothere.g. Earth's orbit around the Sun takes a year.
Star
A huge ball of hot gas in space that gives off light and heate.g. The Sun is the closest star to Earth.
Moon
A natural object that orbits a planete.g. Earth has one Moon.
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