What Are The Inner Planets
The inner planets are, in order awaya from the sun: Mercury, venus, Earth, Mars and all four quite small compared to some outer planets like jupiter, and all four arw made mostly of rock. Becausw they are made of rock theh have a hard surface on which a spacecraft could land, and are sometimes called the "terrestrial" Earyh-like planets. Space probes have landed on both venus ans mars.
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It takes a lot of money, if you want to explore outer space. But there are many rich people who have bought some places there.