Montessori Mom

Look up at the sky. In the daytime you see the sun, and at night you can see the moon, planets, and stars. All of those bodies — plus Earth under our feet — belong to one family called our solar system.

Our place in space

Our solar system is made of:

• One star: the sun at the center.
• Eight planets that orbit the sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.
• Moons that orbit the planets — our own moon orbits Earth.
• Dwarf planets, including Pluto, Ceres, Haumea, Makemake, and Eris.
• Asteroids, meteoroids, and comets — smaller rocky and icy bodies.

Everything here is held together by the sun’s gravity. Earth is the one place we know of with plants and animals, because it has liquid water, oxygen, and a gentle temperature.

The sun

The sun is a medium-sized yellow star that gives us light, heat, and the energy plants use to grow. It still has about five billion years of fuel to burn. For a closer look at its layers — core, radiative zone, convective zone, photosphere, chromosphere, and corona — see our Parts of the Sun lesson.

The planets

The four inner planets (Mercury, Venus, Earth, Mars) are small and rocky. The four outer planets (Jupiter, Saturn, Uranus, Neptune) are huge balls of gas and ice. Mercury is closest to the sun, but Venus is the hottest planet because of its thick cloud blanket. Jupiter is the largest — big enough to hold more than 1,000 Earths inside it. For a full tour, visit our Inner & Outer Planets lesson.

Dwarf planets

Dwarf planets are round bodies that orbit the sun like planets but haven’t cleared the other rocks out of their path. Pluto is the most famous. The current five officially recognized by the International Astronomical Union are Ceres, Pluto, Haumea, Makemake, and Eris.

The moon

Our moon orbits Earth once every 27 days, and its phases (new, waxing, full, waning) take about 29.5 days from one new moon to the next. The moon doesn’t make its own light — it reflects the sun’s light like a mirror. The moon’s gravity also pulls on our oceans and creates the tides.

Stars and constellations

On a clear dark night you can see thousands of stars. Young hot stars are blue giants; older cooler ones are red dwarfs; our sun is a yellow dwarf right in the middle of its life. People have grouped bright stars into pictures called constellations — like the Big Dipper in the northern sky and the Southern Cross in the southern sky.

Asteroids, meteors, and comets

• Asteroids are rocky pieces, most of them in a belt between Mars and Jupiter.
• Meteors are the streaks of light we call “shooting stars” when small rocks burn up entering Earth’s atmosphere.
• Comets are dirty snowballs of ice and dust; their long tails appear when they swing in close to the sun.

Made by people

The newest travelers in the solar system are human-made: the International Space Station, weather and GPS satellites, and probes like Voyager that have now left the planets behind.

Try this at home

1. Toilet-paper solar system. Unroll a long strip of toilet paper down a hallway. Mark the sun at one end and place each planet on the square that matches its distance (there are lots of printable scales online). It’s a striking way to feel how empty space really is.
2. Moon journal. Draw the moon every clear night for a month. Watch the phases go from new to full and back again.
3. Constellation flashlight. Poke pinholes into black paper in the shape of the Big Dipper or Orion, then shine a flashlight through it onto a dark wall.

More to explore on MontessoriMom

• Inner & Outer Planets — meet each planet up close with printable planet cards.
• Parts of the Sun — label the six layers of our star.
• Blood Moon 2026: A Montessori Guide — learn about lunar eclipses and why the moon turns red.
• Space and Geography — astronomy, the moon, and latitude & longitude.
• Earth Science — plate tectonics, volcanoes, and earthquakes beneath our feet.
• Sea Glass and Tides — a beach science adventure connecting the moon’s gravity to ocean tides.
• Earth Day and Folk Art — celebrating culture through nature.
• Planet Cards — Free printable cards for all eight major planets.
• Dwarf Planets — Explore Pluto, Eris, Ceres, Haumea, and Makemake.
• Astronomy Printouts — Browse our complete collection of free printable astronomy materials.

Hands-on materials

• Ravensburger The Planets Jigsaw Puzzle — a beautiful 100-piece puzzle for ages 6+.
• LEGO Ideas NASA Apollo Saturn V — build a 1-meter-tall moon rocket (ages 14+, great family project).

Books we like

• DK Space! The Universe as You’ve Never Seen It Before — rich photos and diagrams for ages 7–12.
• Gail Gibbons, The Planets — a friendly picture-book tour for ages 4–8.

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