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Yr9 Astronomy
Yr 9 astronomy definitions all
| Term | Definition |
|---|---|
| Asteroid belt | An area between the orbits of Mars and Jupiter where millions of asteroids orbit the Sun. |
| Asteroids | Small, rocky objects that orbit the Sun. Most of the over 600,000 are found orbiting in the Asteroid Belt, a series of rings located between the orbits of Mars and Jupiter. |
| Big Bang Theory | A scientific model that describes how the universe began with a giant blast of matter and energy about 14 billion years ago. Right after the explosion our universe began to cool and expand, and eventually atoms, stars, galaxies and solar systems formed. |
| Comet | Small celestial bodies composed primarily of frozen ammonia, methane or water, and contain only small amounts of rocky material. Nicknamed "dirty snowballs." Made up of a nucleus, a coma, a dust tail and an ion tail. Orbit the Sun in elliptical paths. |
| Day | When the Earth is facing the Sun and receiving light. |
| Earth | Third planet from the Sun. The only planet known to have life because of an atmosphere containing free oxygen and oceans of water |
| Edwin Hubble | He determined that there are other galaxies in the Universe other than the Milky Way Equinox Two times in the year when the Sun is exactly above the equator and day and night are of equal length. Occur in Spring and Autumn. |
| Galaxy | A system consisting of a large number of stars bound together by gravity |
| Galileo Galilei | He first used the telescope to view the stars and planets in 1609. |
| Gravity | The force by which a planet or other body draws objects towards its centre. This force keeps all of the planets in orbit around the sun and keeps moons in orbit around planets. |
| Isaac Newton | In 1668 he invented the first reflecting telescope and described the motion of the Sun and the planets. |
| Johannes Kepler | He discovered that planets and other objects travel in elliptical orbits around the sun, which led to the three laws of planetary motion. He was the first astronomer to observe a supernova. |
| Jupiter | The 5th planet from the Sun, largest in the Solar System and has 79 + moons. It is a gas giant with a mass 1/1000 that of the Sun, but 2.5 times that of all the other planets in the Solar System combined. Is the third brightest object in the night sky. |
| Light Year | The distance that light travels in empty space in one year (9,500,000,000,000 kilometres) |
| Lunar Eclipse | When the Earth blocks the Sun’s light causing a shadow on the Moon |
| Mars | The fourth planet from the Sun and the second-smallest planet in the Solar System after Mercury. Known as the red planet. |
| Mercury | The smallest and innermost planet in the Solar System. Its orbit around the Sun takes only 87.97 days, the shortest of all the planets in the Solar System. |
| Meteor | Is a small rock or particle of debris in our solar system. They range in size from dust to around 10 metres in diameter. |
| Meteorite | Is a meteoroid that survives falling through Earth’s atmosphere and collides with the Earth’s surface. |
| Meteoroid | A small rock or particle of debris in our solar system. They range in size from dust to around 10 metres in diameter. |
| Milky Way | Earth’s galaxy, that contains our Solar system and many other stars and planets |
| Moon | A celestial body that makes an orbit around a planet. |
| Neap Tide | A low high tide due to the Sun being at 90 degrees with respect to the Earth |
| Neptune | The most distant planet from the Sun. Neptune is the smallest gas giant. Is named after the Roman god of the sea. Has 6 faint rings. |
| Nicolaus Copernicus | Astronomer from 1543 that claimed that the Earth and the planets orbited the Sun. |
| Night | When the Earth is not receiving light from the Sun and is in the dark. |
| Planet | A large celestial object that has become rounded due to its gravity and has cleared is nearby region of other smaller objects. Planets in the solar system include Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune |
| Ptolomy | In the 100s he constructed the Ptolemaic model, which stated that all objects revolved around the Earth. This model lasted for 1400 years. |
| Revolution | When a planet or a moon travels (orbits) once around an object (e.g Earth orbits the Sun) |
| Rotation | When a planet or moon turns all the way around or spins on its axis once. |
| Satellite | A natural or artificial object that is in orbit around a planet. |
| Seasons | Caused by the tilt of the Earth’s axis and Earth’s elliptical orbit around the Sun. When tilted toward the Sun we get summer and when tilted away we get winter |
| Solar Eclipse | When the Moon blocks the Sun’s light causing a shadow on the Earth |
| Solar system | Centred around the Sun, includes 8 planets, their moons, comets and asteroids |
| Solstice | When the Sun is at its greatest distance from the celestial equator, occurs in summer and winter. |
| Spring Tide | A very high tide due to the Sun-Earth-Moon alignment |
| Star | A giant ball of hot gas and plasma that generates huge amounts of energy through nuclear fusion. |
| Telescope | An instrument used to view objects in outer space. |
| Tide | The rise and fall of the levels of the ocean. They are caused by the gravitational pull of the Sun and Moon as well as the rotation of the Earth. |
| Universe | The universe is everything that exists including the stars, planets, matter, energy and time. |
| Uranus | The seventh planet from the Sun in the Solar System. It is a gas giant. It is the third largest planet in the solar system. It has five big moons, many small ones, and a small system of 13 planetary rings. |
| Venus | The second planet from the Sun. It is named after the Roman goddess of love and beauty. The second-brightest natural object in the night sky after the Moon. Known as the morning star and evening star. |
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