A planet is a celestial body with three key characteristics. First, it must orbit a star. Second, it must have enough mass for its own gravity to make it roughly round in shape. Third, it must have cleared the neighborhood around its orbit of other objects.
Our solar system has eight planets, starting with the four inner planets. Mercury is the closest to the Sun and smallest planet. Venus is the hottest planet due to its thick atmosphere. Earth is our home planet with liquid water and life. Mars is known as the red planet because of iron oxide on its surface.
The four outer planets are gas giants, much larger than the inner planets. Jupiter is the largest planet in our solar system. Saturn is famous for its beautiful ring system. Uranus is unique because it rotates on its side. Neptune is the windiest planet with storms reaching over 1,200 miles per hour.
Beyond our solar system, there are countless exoplanets orbiting other stars throughout the galaxy. Scientists have discovered over 5,000 exoplanets using various detection methods. These distant worlds come in many sizes and compositions. Some exoplanets orbit within their star's habitable zone, where conditions might be suitable for liquid water and potentially life.
In summary, planets are remarkable celestial bodies that orbit stars. Our solar system contains eight diverse planets, from the small rocky inner planets to the massive gas giants in the outer regions. Beyond our solar system, thousands of exoplanets have been discovered, showing us that planetary systems are common throughout the universe. Each planet is unique, contributing to our understanding of how planetary systems form and evolve.