Grade 4

Exploring Space


there is a picture of ten planets.
  • Mercury
  • Venus
  • Earth
  • Earths Moon
  • Mars
  • Jupiter
  • Saturn
  • Uranus
  • Neptune
  • Pluto

Photography Credit: Solar System Montage NASA/JPL-Caltech


The comet Kohoutek is a frozen ball of ice streaking through space. As it gets closer to the Sun, some of the ice melts and forms a beautiful tail of gas and dust.
Photography Credit: NASA Johnson Space Center (NASA-JSC)
This is the Stardust spacecraft. Scientists have sent it on a long journey to collect dust from a comet's tail and bring it back to Earth to study.
Photography Credit: NASA/JPL


Asteroids are chunks of rock in space that orbit the Sun. Some are as big as houses or even mountains. Scientists have named this asteroid Ida.
Photography Credit: NASA Jet Propulsion Laboratory (NASA-JPL)


Meteors are fragments of rock—most no bigger than grains of sand—that fall from space to Earth. We call them “shooting stars” when they burn and glow as they streak across the night sky. This little rock, which is about two inches across, is a piece of an asteroid that fell all the way to Earth.
Photography Credit: JPL and NASA

Milky Way

There are billions of stars in the Milky Way Galaxy—including our own Sun.
Photography Credit: NASA Goddard Space Flight Center


To move in a path, usually around a planet or a star.

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  1. Of the objects mentioned in this article, which object is the Moon most like?
    Write a sentence or two to explain your answer.
  2. How would life be different on Earth if Earth did not have a moon?
    Imagine the Moon did not exist. Write a paragraph about how life on Earth might be different.