Planets in the Milky Way Galaxy

Uranus is the seventh planet from the Sun and is known for its unique sideways rotation. It’s an ice giant composed mostly of icy materials like water, methane, and ammonia, along with hydrogen and helium. This gives the planet a pale blue color due to the methane in its atmosphere, which absorbs red light and reflects blue. Uranus has faint rings and at least 27 known moons, all named after characters from Shakespeare and Alexander Pope. With frigid temperatures and an axial tilt of about 98 degrees, Uranus experiences extreme seasons that last over 20 Earth years each.

Saturn is the sixth planet from the Sun and is best known for its stunning ring system, which is made up of ice, rock, and dust particles. It’s a gas giant like Jupiter, composed mostly of hydrogen and helium, with a low density—so low, in fact, that Saturn could float in water if there were a bathtub big enough! Saturn has a strong magnetic field and over 140 known moons, including Titan, a moon with a thick atmosphere and lakes of liquid methane. Despite its size and beauty, Saturn has fierce storms and powerful winds that can reach speeds of over 1,800 kilometers per hour.

Jupiter is the fifth planet from the Sun and the largest in our solar system, so massive that it could fit all the other planets inside it. It’s a gas giant made mostly of hydrogen and helium, with no solid surface. Jupiter is famous for its Great Red Spot, a giant storm that has been raging for centuries. The planet has a strong magnetic field and dozens of moons, including Ganymede—the largest moon in the solar system. Its fast rotation, taking less than 10 hours to spin once, causes the planet to bulge at the equator and gives it its distinctive banded appearance.

Mars is the fourth planet from the Sun and is often called the “Red Planet” due to its reddish appearance, caused by iron oxide (rust) on its surface. It has a thin atmosphere made mostly of carbon dioxide and experiences seasons like Earth, thanks to its tilted axis. Mars is home to the tallest volcano in the solar system, Olympus Mons, and the deepest canyon, Valles Marineris. Though cold and dry today, evidence suggests that liquid water once flowed on its surface. Scientists continue to study Mars closely, as it remains a top candidate in the search for past or present extraterrestrial life.

Earth is the third planet from the Sun and the only known planet to support life. It has a diverse environment with vast oceans, continents, mountains, and a breathable atmosphere rich in nitrogen and oxygen. Earth’s surface is about 71% water, which helps regulate its climate and sustain countless life forms. It has a protective magnetic field and ozone layer that shield it from harmful solar radiation. Earth experiences seasons due to its axial tilt and completes one orbit around the Sun in about 365 days. Its unique balance of air, water, and temperature makes it a truly remarkable planet in our solar system.

Mercury is the smallest planet in our solar system and the one closest to the Sun. It has a rocky surface covered in craters, similar to Earth’s Moon, and has no atmosphere to speak of, which means temperatures swing dramatically from scorching hot during the day to freezing cold at night. Mercury orbits the Sun very quickly—just 88 Earth days per year—but rotates very slowly, so one day on Mercury lasts about 59 Earth days. Despite being so close to the Sun, it’s not the hottest planet—that title goes to Venus due to its thick atmosphere.

Venus is the second planet from the Sun and is often called Earth’s “sister planet” due to its similar size and composition. However, its environment is drastically different—Venus has a thick, toxic atmosphere made mostly of carbon dioxide, with clouds of sulfuric acid, creating a runaway greenhouse effect that makes it the hottest planet in the solar system. Its surface is rocky, marked by volcanoes and vast plains, and temperatures can soar above 460°C. Venus rotates very slowly and in the opposite direction of most planets, meaning a day on Venus is longer than its year.