The Inner Planets: Earth and Mars

Earth is the third planet from the Sun and the only known planet where life exists. It has the perfect combination of water, oxygen, sunlight, and temperature needed to support millions of different living organisms. Earth’s atmosphere is mainly made of nitrogen and oxygen, and it protects the planet from harmful solar radiation while also keeping the surface warm enough for life. The planet is divided into seven continents and five oceans, with about 70% of its surface covered by water. Earth rotates on its axis every 24 hours, creating day and night, and it takes about 365 days to complete one orbit around the Sun. The Moon affects Earth’s tides and helps stabilize the planet’s tilt, which influences the seasons. Scientists continue to study Earth to better understand climate, weather, natural resources, and the ecosystems that support life.

Mars is the fourth planet from the Sun and one of the most explored planets in the solar system. It is often called the “Red Planet” because its surface contains iron oxide, or rust, which gives it a reddish color. Mars has the largest volcano in the solar system, Olympus Mons, and a massive canyon system called Valles Marineris. Although Mars is very cold and dry today, scientists have discovered evidence that liquid water once existed on its surface billions of years ago. The planet has two small moons, Phobos and Deimos, and experiences dust storms that can cover the entire planet.