Lesson 04 – Moons

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Read About Moons


Read the vocabulary terms to understand the reading better.

Moons are celestial bodies that orbit larger celestial bodies.

The solar system is the Sun and the eight planets and other celestial bodies that orbit around the Sun.

The atmosphere is a layer or set of layers of gases that surround Earth.

Asteroids are small rocky objects that orbit the Sun.

Comets are small icy objects in space; when a comet comes close to the Sun, the comet gives off gases and dust that produce a large glowing ball around the comet and a long tail behind it.

Meteorites are space rocks that fall to Earth’s surface.

Gravity is the force that attracts objects toward one another (e.g., gravity pulls objects toward the ground).

Tides are the rising and falling of the ocean’s surface twice a day that are caused by gravitational forces from the Sun and Moon.

A lunar eclipse is a darkening of the Moon that is caused by the Moon passing through Earth’s shadow.


Did you know there are likely about 140 moons in our solar system? Jupiter has more than 64 moons. Mercury and Venus are the only planets that do not have a moon.

A moon can be any size. Two moons in our solar system are even bigger than Mercury. The second-largest moon is Titan, which orbits Saturn. Scientists are very interested in Titan because its atmosphere seems similar to Earth’s long ago. Could there be life there now or sometime in the future?

Our Moon is about one-quarter the size of Earth. The surface is covered with boulders and a thick layer of grey dust. There are many large craters and mountain ranges, but no atmosphere. Millions of asteroids, comets, and meteorites have scarred the Moon’s surface. There is no wind or rain to wash away these marks, so they remain unchanged for years.

The view of the earth from our moon

The Moon Affects Life on Earth

The Moon circles Earth, reflecting light from the Sun and pulling on Earth’s oceans.

Ocean tides are caused by the Moon’s gravity pulling the water toward the Moon. Since Earth rotates as this happens, two tides happen every day.

A lunar eclipse occurs when Earth comes between the Sun and the Moon. Earth’s shadow makes the whole Moon look red and mysterious.

The Sun and Moon must be exactly opposite each other for a total eclipse. Partial eclipses happen much more often. A few lunar eclipses happen each year. Most can only be seen from certain places on Earth, depending on where the darkest shadow passes.

Phases of the Moon

Do you ever wonder why the Moon looks so bright in the night sky? This is because the surface of the Moon reflects the light from the Sun. The part of the Moon facing the Sun is lit up. The part of the Moon facing away from the Sun is dark. The sunlit part of the moon that we see is what is responsible for the Moon’s phases. The phases of the Moon depend on its position in relation to the Sun and Earth. As the Moon makes its way around the Earth, the phases of the Moon change.

To learn more about the Moon, watch the video by National Geographic on Youtube.

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