Système solaire: Planètes internes

• The solar system is composed of inner and outer planets

Inner Planets

• Inner planets are Mercury, Venus, Earth and Mars
• They are also known as terrestrial planets because of their rocky composition
• They are closer to the Sun than the outer planets
• They have shorter orbital periods than the outer planets
• They are smaller in size and mass compared to the outer planets
• They are primarily composed of silicate rocks and metals
• They have higher densities than the outer planets
• They have thinner atmospheres than the outer planets, or no atmosphere at all
• They have fewer or no moons compared to the outer planets
• They have warmer surface temperatures than the outer planets, due to their proximity to the Sun

Mercury

• Mercury is the closest planet to the Sun
• It is the smallest planet in the Solar System
• It has a heavily cratered surface, similar to the Moon
• It has no natural satellites (moons)
• It has a very thin atmosphere, almost a vacuum
• It experiences extreme temperature variations, from very hot during the day to very cold at night
• It has a large iron core, which makes up a significant portion of its interior
• It has a weak magnetic field, which is about 1% the strength of Earth's
• Its surface gravity is about 38% of Earth's
• A day on Mercury (sidereal rotation period) is about 59 Earth days
• A year on Mercury (orbital period) is about 88 Earth days

Venus

• Venus is the second planet from the Sun
• It is often called Earth's "sister planet" because of its similar size and composition
• It has a thick, toxic atmosphere composed primarily of carbon dioxide
• It has a surface temperature hot enough to melt lead
• It exhibits a strong greenhouse effect, trapping heat in its atmosphere
• It rotates in the opposite direction (retrograde) compared to most other planets
• It has no natural satellites (moons)
• It has a relatively smooth surface with some mountains and valleys
• Atmospheric pressure at the surface is about 90 times that of Earth's
• It is the hottest planet in our solar system
• A day on Venus (sidereal rotation period) is about 243 Earth days
• A year on Venus (orbital period) is about 225 Earth days

Earth

• Earth is the third planet from the Sun
• It is the only known planet to support life
• It has a diverse atmosphere composed mainly of nitrogen and oxygen
• It has liquid water on its surface, covering about 71% of the planet
• It has a strong magnetic field, which protects it from harmful solar radiation
• It has one natural satellite, the Moon
• It is composed of several layers: a crust, mantle, outer core, and inner core
• It experiences a wide range of climates and weather patterns
• It has active plate tectonics, which shape its surface
• A day on Earth (sidereal rotation period) is about 24 hours
• A year on Earth (orbital period) is about 365.25 days

Mars

• Mars is the fourth planet from the Sun
• It is often called the "Red Planet" because of its reddish appearance
• It has a thin atmosphere composed primarily of carbon dioxide
• It has a surface with impact craters, volcanoes, valleys, deserts, and polar ice caps
• It has evidence of past liquid water on its surface, including dried riverbeds and lakes
• It has two small natural satellites, Phobos and Deimos
• It experiences seasonal variations, similar to Earth
• Its surface gravity is about 38% of Earth's
• It is currently being explored by rovers and orbiters, seeking evidence of past or present life
• A day on Mars (sidereal rotation period) is about 24.6 hours
• A year on Mars (orbital period) is about 687 Earth days

Outer Planets

• Outer planets consist of Jupiter, Saturn, Uranus, and Neptune
• They are also known as gas giants or Jovian planets because of their gaseous composition
• They are located farther from the Sun than the inner planets
• They have longer orbital periods than the inner planets
• They are much larger in size and mass compared to the inner planets
• They are primarily composed of hydrogen and helium
• They have lower densities than the inner planets
• They have thick atmospheres with prominent cloud bands and storms
• They have numerous moons and ring systems
• They have colder surface temperatures than the inner planets, due to their distance from the Sun

Jupiter

• Jupiter is the fifth planet from the Sun
• It is the largest planet in the Solar System
• It is a gas giant, composed primarily of hydrogen and helium
• It has a strong magnetic field, the strongest of any planet in the Solar System
• It has a prominent Great Red Spot, a giant storm that has been raging for centuries
• It has at least 95 known moons, including the Galilean moons (Io, Europa, Ganymede, and Callisto)
• It has a faint ring system
• Its rapid rotation causes its shape to bulge at the equator
• A day on Jupiter (sidereal rotation period) is about 10 hours
• A year on Jupiter (orbital period) is about 12 Earth years

Saturn

• Saturn is the sixth planet from the Sun
• It is famous for its prominent ring system, composed of ice particles and debris
• It is a gas giant, composed primarily of hydrogen and helium
• It has at least 146 known moons, including Titan, which has a thick atmosphere
• It has a magnetic field weaker than Jupiter's but still stronger than Earth's
• Its density is so low that it would float in water
• Its upper atmosphere exhibits banded patterns, similar to Jupiter
• A day on Saturn (sidereal rotation period) is about 10.7 hours
• A year on Saturn (orbital period) is about 29.5 Earth years

Uranus

• Uranus is the seventh planet from the Sun
• It is an ice giant, composed primarily of hydrogen, helium, and methane
• It has a bluish-green color due to the absorption of red light by methane in its atmosphere
• It rotates on its side, with its axis of rotation tilted almost 98 degrees
• It has a faint ring system
• It has at least 27 known moons
• It has a magnetic field that is tilted and offset from the planet's center
• A day on Uranus (sidereal rotation period) is about 17 hours
• A year on Uranus (orbital period) is about 84 Earth years

Neptune

• Neptune is the eighth planet from the Sun
• It is an ice giant, composed primarily of hydrogen, helium, and methane
• It has a deep blue color due to the absorption of red light by methane in its atmosphere
• It has strong winds, the fastest in the Solar System
• It has a faint ring system
• It has at least 16 known moons, including Triton, which orbits in the opposite direction of Neptune's rotation
• It has a magnetic field that is tilted and offset from the planet's center
• A day on Neptune (sidereal rotation period) is about 16 hours
• A year on Neptune (orbital period) is about 165 Earth years