THE SOLAR SYSTEM

BODIES IN THE SOLAR SYSTEM Our planet, Earth, is part of a system of planets that orbit a star, the sun. The solar system is comprised of the following major bodies (listed in order from closest to the sun to farthest away) The sun (the star at the center of the solar system) Mercury (planet) Venus (planet) Earth (planet) The moon (orbits Earth) Mars (planet) The asteroid belt Jupiter (planet) Saturn (planet) Uranus (planet) Neptune (planet) The Kuiper belt (contains asteroids and dwarf planets, such as Pluto)

PROPERTIES OF THE SOLAR SYSTEM All eight planets orbit the sun in the same direction, but at different angular speeds. The planets lie in a disc (called the solar plane) surrounding the sun. The planetary orbits are elliptical (oval shaped). However, if I projected their orbits on a screen, they would appear to be nearly circular. The sun and all eight planets formed out of the same original nebula (dust cloud).

THE SUN The sun provides both the strongest source of gravity and light in the solar system. It is the “main body” in the solar system. The sun is a star. It creates light via the process of nuclear fusion. Mass = x kg Diameter = 1,391,600 km

MERCURY Mercury is a rocky (solid) planet. It is the planet closest to the Sun. It is the smallest planet and has the fastest orbit around the sun. Mass = x kg Diameter = 4,879 km Orbital radius = 57,910,000 km Orbital period = 88 days

VENUS Venus is a rocky planet and is often referred to as the “morning star” and “evening star” Mass = x kg Diameter = 12,100 km Orbital radius = 108,200,000 km Orbital period = 225 days

EARTH Earth is the planet on which we live. It is the only planet in the universe known to harbor life. Mass = x kg Diameter = 12,740 km Orbital radius = 149,600,000 km Orbital period = ~365 days

THE MOON A moon is a body that orbits a planet. While other planets in our solar system have moons, the Earth’s moon is by far the largest in size and mass compared to its parent planet. The moon was most likely created when a large body (about the size of Mars) collided with Earth during its early formation. Mass = x kg Diameter = 3,474 km Orbital radius = 384,400 km (around Earth) Orbital period = ~28 days (around Earth)

MARS Mars is a rocky planet and is often called the “red planet.” Mars has frozen water on its surface and at one time had a magnetic field and atmosphere much like Earth. Mass = 6.39 x kg Diameter = 6,779 km Orbital radius = 227,900,000 km Orbital period = 687 days

THE ASTEROID BELT The asteroid belt is a region located between Mars and Jupiter which contains many small bodies called asteroids. The largest body within the asteroid belt is Ceres. The total mass of the belt is about equal to 4% the mass of the moon.

JUPITER Jupiter is the largest planet in our solar system. It is often called a “gas giant.” Jupiter has close to the amount of mass needed to turn a body into a star. Mass = x kg Diameter = 139,800 km Orbital radius = 778,600,000 km Orbital period = years

SATURN Saturn is a “gas giant” planet and is often regarded as the most beautiful planet in our solar system due to its rings. Mass = x kg Diameter = 116,500 km Orbital radius = 1,433,000,000 km Orbital period = years

URANUS Uranus was first discovered by humans in It is one of two planets that cannot be seen from Earth with the naked eye. Uranus is a gaseous planet and often referred to as an “ice giant.” Mass = x kg Diameter = 50,720 km Orbital radius = 2,877,000,000 km Orbital period = years

NEPTUNE Neptune was first discovered by humans in Since its discovery, it has orbited the sun only one time! Neptune is a gaseous planet and is often referred to as an “ice giant.” Mass = x kg Diameter = 49,250 km Orbital radius = 4,503,000,000 km Orbital period = years

THE KUIPER BELT The Kuiper belt is a region of space beyond that planets that contains asteroids and dwarf planets. The Kuiper belt is similar to the asteroid belt, but much larger. It is about times as massive and about 20 times wider than the asteroid belt. The dwarf planet Pluto is in the Kuiper belt.

PLANETARY SYMBOLS Historically, the following symbols have been used to label the Sun, Moon, and planets.