Space Exploration Revision PDF

SPACE EXPLORATION: REVISION +-----------------------------------+-----------------------------------+ | **Observing the Night Sky** | | +===================================+===================================+ | **Key Concepts** | **Vocabula...

SPACE EXPLORATION: REVISION +-----------------------------------+-----------------------------------+ | **Observing the Night Sky** | | +===================================+===================================+ | **Key Concepts** | **Vocabulary** | +-----------------------------------+-----------------------------------+ | Astronomy is the scientific study | - Astronomy | | of what exists beyond the Earth | | | (space). Everything that | - Space | | physically exists is part of the | | | Universe. | - The Universe | | | | | Many celestial bodies can be seen | - Celestial body | | in the night sky: | | | | - Star | | - Stars (like the Sun) are | | | massive celestial bodies made | - The Sun | | up of hot gases. Stars are | | | bright. The planets and the | - The solar system | | moon reflect sunlight. | | | | - Planet | | - The solar system comprises | | | the Sun and all the celestial | - Terrestrial planet | | bodies that revolve around | | | it. | - Gas giant | | | | | - The eight planets in the | - Ice Giant | | solar system are terrestrial | | | planets (Mercury, Venus, | - Earth | | Earth, Mars), gas giants | | | (Jupiter, Saturn), and ice | - The moon | | giants (Uranus, Neptune). | | | | - Galaxy | | - Natural satellites (moons), | | | such as the Moon, orbit | - The Milky Way | | certain planets in the solar | | | system. | | | | | | - The Universe is made up of | | | billions of galaxies, just | | | like the Milky Way. Each | | | galaxy contains billions of | | | stars and other celestial | | | bodies. | | +-----------------------------------+-----------------------------------+ +-----------------------------------+-----------------------------------+ | **The Solar System** | | +===================================+===================================+ | **Key Concepts** | **Vocabulary** | +-----------------------------------+-----------------------------------+ | The solar system consists of the | - Solar system | | Sun, eight planets and their | | | moons, and billions of smaller | - Planet | | bodies. All these celestial | | | bodies revolve around the sun. | - Terrestrial planet | | | | | Planets can be compared by | - Gas giant | | describing their characteristics: | | | type, size, mass, length of year, | - Ice Giant | | number of moons, average distance | | | from the Sun, minimum and maximum | - Dwarf planet | | temperature. | | | | | | Dwarf planets are smaller than | | | the planets. | | +-----------------------------------+-----------------------------------+ +-----------------------------------+-----------------------------------+ | **The Sun** | | +===================================+===================================+ | **Key Concepts** | **Vocabulary** | +-----------------------------------+-----------------------------------+ | The star at the centre of our | - The Sun | | solar system is called the Sun. | | | It consists largely of hydrogen | - Nuclear fusion | | and helium. The Sun is essential | | | to life on Earth. | - Solar radiation | | | | | Nuclear fusion at the heart | - Gravitational force | | (nucleus) of the Sun releases a | | | huge amount of energy (solar | - Magnetic field | | radiation) that escapes from the | | | photosphere. The gravitational | - Sunspot | | force of the Sun holds the solar | | | system together. | - Solar flare | | | | | The magnetic field of the Sun | | | encases the entire solar system | | | and protects the planets. | | | Sunspots are darker, colder areas | | | on the surface of the Sun that | | | have strong pockets of magnetism. | | | Solar flares release large | | | amounts of charged gas and | | | particles. | | +-----------------------------------+-----------------------------------+ +-----------------------------------+-----------------------------------+ | **The Lives of Stars** | | +===================================+===================================+ | **Key Concepts** | **Vocabulary** | +-----------------------------------+-----------------------------------+ | There are changes in the night | - Constellation | | sky, due to the rotation of the | | | Earth, the distance from | - Nuclear fusion | | celestial bodies, and the | | | revolution of the Earth around | - Nebula | | the Sun. | | | | - Red giant | | The sky is divided into 88 | | | constellations. | - White dwarf | | | | | Stars shine because of the | - Red supergiant | | nuclear fusion process. | | | | - Supernova | | A star is formed in a massive | | | cloud of gas and dust called a | - Neutron star | | nebula. | | | | - Black hole | | When stars have run out of fuel, | | | they become white dwarfs, neutron | | | stars, or black holes. The mass | | | of a star determines its | | | evolution or life cycle. | | | | | | A star of the same type as the | | | Sun will become a red giant, then | | | a white dwarf. | | | | | | A star more massive than the Sun | | | will become a red supergiant, | | | then a supernova, then either a | | | neutron star or a black hole. | | +-----------------------------------+-----------------------------------+ +-----------------------------------+-----------------------------------+ | **Earth, Moon, Sun** | | +===================================+===================================+ | **Key Concepts** | **Vocabulary** | +-----------------------------------+-----------------------------------+ | The greater the mass of the | - Gravitational force | | object, the greater its | | | gravitational force. The | - Rotation | | gravitational force of the very | | | massive Sun is sufficient to keep | - Revolution | | the Earth in orbit. Similarly, | | | the strong gravity of the Earth | - Earth's tilt | | keeps the Moon in orbit around | | | it. | - Phases of the Moon | | | | | The rotation of a celestial body | - Lunar cycle | | refers to the fact of turning on | | | itself. The rotation of the Earth | - Solar eclipse | | takes about 24 hours and from | | | west to east. | - Lunar eclipse | | | | | The Earth's revolution is the | - Tides | | path that the Earth takes around | | | the Sun. The duration of the | | | Earth's revolution is 365.25 | | | days. | | | | | | The orbit of the Earth, like | | | those of other planets, has the | | | shape of an ellipse. Astronomers | | | call the average distance between | | | each planet and the Sun an | | | orbital radius. Earth has an | | | orbital radius of 1 AU. | | | | | | The rotation axis of the Earth is | | | tilted 23.5° from the vertical of | | | its orbital plane, which affects | | | the seasons. | | | | | | The Moon takes about the same | | | time to make a rotation on itself | | | as it does to go around the Earth | | | (27.3 days). As a result, the | | | face of the Moon that is oriented | | | towards the Earth is always the | | | same. | | | | | | Over a period of about four | | | weeks, the illuminated region of | | | the moon that we see (phases of | | | the moon) varies regularly. The | | | eight phases constitute a lunar | | | cycle. | | | | | | A solar eclipse occurs when the | | | Moon is placed directly between | | | the Earth and the Sun; it | | | prevents the Sun from being seen | | | from the Earth. | | | | | | A lunar eclipse occurs when the | | | Earth, placed between the Sun and | | | the Moon, casts a shadow on the | | | Moon. | | | | | | Tides are the rise and fall of | | | the surface of the oceans. They | | | are caused by the gravitational | | | force of the Moon and, less | | | significantly, the Sun. | | +-----------------------------------+-----------------------------------+ +-----------------------------------+-----------------------------------+ | **The Origin of the Universe/ The | | | formation of the Solar System** | | +===================================+===================================+ | **Key Concepts** | **Vocabulary** | +-----------------------------------+-----------------------------------+ | The universe is expanding, and | - Big Bang theory | | this expansion is accelerating. | | | | - Solar nebula theory | | According to the Big Bang theory, | | | the Universe was born because of | | | a sudden expansion that took | | | place 13.7 billion years ago. | | | | | | According to the solar nebula | | | theory, the solar system formed | | | in a giant disc of swirling gas | | | and dust. | | +-----------------------------------+-----------------------------------+