Exploring the Solar System: Planets and Celestial Bodies

• The solar system consists of celestial bodies, including the sun as its center, planets, and other celestial objects that orbit the sun.

What is the Sun?

• The sun is a large, hot ball of gas.
• The surface temperature of the sun reaches 6,000°C, while its center reaches 15 million °C
• The distance between the sun and Earth is approximately 150 million km.

Celestial Bodies Orbiting the Sun

• Planets
• Comets
• Asteroids
• Meteors
• Satellites

Planets

• Planets do not have their own light.
• The light of planets is a reflection of the sun's light.
• Planets revolve around the sun through a path, known as an orbit.
• Planetary orbits are elliptical, so the distance of a planet from the sun is inconsistent.
• The direction of planetary orbit is opposite to the direction of the hands of a clock.
• Planets orbit the sun due to the gravitational force of the sun.
• Planetary orbits around the sun are referred to as revolutions.
• The time it takes for a planet to complete one revolution is called the period of revolution.
• The farther a planet is situated from the sun, the longer its period of revolution will be.
• Planets also rotate on their axes.
• Rotation is planetary movement on its own axis.
• The time it takes for a planet to complete one rotation is termed the period of rotation.

Planets in the Solar System

• Mercury
• Venus
• Earth
• Mars
• Jupiter
• Saturn
• Uranus
• Neptune

Planet Classification

• Planets are grouped into two categories based on their orbital positions.
• The asteroid belt divides the planets into two categories.
• Inner Planets: Mercury, Venus, Earth, and Mars
• Outer Planets: Jupiter, Saturn, Uranus, and Neptune

Mercury

• Mercury is the smallest planet and is closest to the sun.
• The distance between Mercury and the sun is approximately 58 million km.
• Mercury is not covered by an atmospheric layer like Earth.
• Mercury does not possess any satellites.

Venus

• Venus is the second planet in the solar system.
• Venus orbits the sun faster than it rotates on its axis.
• Venus does not have satellites.
• The direction of rotation goes against that of other planets, going from East to West
• Venus is the hottest planet because its atmosphere consists of carbon dioxide gas.
• Venus is often called the Morning Star/Evening Star

Earth

• Earth is the only planet inhabited by living beings.
• The surface of Earth consists of oceans and land.
• Earth is enveloped by a layer of air known as the atmosphere.
• Earth has one satellite: the moon.
• Earth rotates on its axis for 24 hours.
• Earth revolves around the sun for 365¼ days.

Mars

• Mars is known as the red planet.
• Mars has two satellites, Phobos and Deimos.
• The rotation period on Mars is 24.6 hours, and the revolution of Mars is 687 days.
• The surface of Mars shows black spots that are craters.
• The gravitational pull on Mars is smaller than the Earth's.

Jupiter

• Jupiter is the largest planet in the solar system.
• Jupiter is faster to rotate than Earth, at 9 hours 55 minutes.
• The orbital revolution around the sun is 11.9 Earth years.
• Jupiter has multiple satellites, the 4 largest being Ganymede, Callisto, Europa, and Io.
• Jupiter has an atmospheric temperature of -140°C, meaning no life can survive on the planet.

Saturn

• Saturn is known for the rings that encircle it.
• Saturn is the second largest planet after Jupiter.
• Saturn's largest satellite is Titan.
• Saturn takes 29.5 years to orbit the Sun.
• Saturn's rotation period is ±10.7
• Saturn is mostly comprised of Hydrogen and Helium.

Uranus

• Uranus is often referred to as a twin planet of Neptune because they both consist of gas and ice.
• Uranus is surrounded by thick clouds, making it complex to observe.
• Uranus is very cold because it is far from the sun.
• Its largest satellites are Miranda, Ariel, Umbriel, Titania, and Oberon.

Neptune

• Neptune is known to be Uranus' twin planet due to the two's similar size to Uranus.
• Neptune's largest satellites are Triton, Nereid, and Proteus.
• Triton is its only satellite to have a backwards orbit.

Asteroids

• Asteroids are small celestial objects revolving around the sun in a ring shape.
• The asteroid path is called an asteroid belt
• Most lie between Mars and Jupiter.
• The largest asteroid is called Ceres.

Meteoroids

• Meteroids are small pieces of matter located in interplanetary space.
• A meteoroid that enters the Earth's atmosphere is called a meteor
• Meteoroids burn with friction in the atmosphere
• Meteors that reach the Earth's surface are called meteorites.
• Meteors are "shooting stars"

Comets

• A comet is a celestial object in the form of a ball of ice and dust that orbits the Sun in the solar system.
• When it crosses the sun, the comet receives the push of the sun's wind so that its burning tail is behind it. The comet's tail always moves away from the sun
• Therefore comets are also known as tailed stars.
• Halley's Comet is noticeable every 75-76
• Halley's Comet last appeared in the solar system in 1986
• Encke's Comet is observed every 3.3 years
• Encke's periodic comet was the second to be spotted after Halley's comet.

Satellites

• Satellites orbit another object with specific periods of revolution and rotation.
• There are two types, natural and man-made.
• Natural satellites form of their own accord, and orbit planets.
• Man-made satellites are implements made by humans for communication, weather forecasting, or pinpointing locations of specific locations on Earth.
• Sputnik I (Russia): The first satellite to be owned by the Soviet Union (1922-1991) and was launched into outer space on October 4, 1957
• Palapa Satellite (Indonesia): On July 9, 1976, Indonesia successfully launched the Palapa A1 Satellite, which was also the first satellite in the Asian region.
• Navstar Satellite (United States): The first GPS (Global Positioning System) satellite was launched in 1978 and developed by the United States Department of Defense.