The time it takes for a planet to orbit the Sun once
E.g. Earth's orbital period lasts 365.26 days
The time it takes for a planet to revolve once around it's own axis
E.g. Earth's rotation takes 24 hours to complete
A series of stars that form a notable pattern in the night sky
E.g. Canis Major and Cetus
The distance that light travels in one year
The speed of light is 300 000 km/s
This means that light travels 9.5 x 10^12 km in one year
The brightness of a star as seen from Earth
A smaller group of stars that make a patter inside a constellation
E.g. Orion's Belt and the Summer Triangle
Stars used to find an area in the sky or for navigation.
E.g. Following Polaris will lead people North.
Constellations that appear all year.
E.g. Cepheus and Cassiopeia
The constellations you would see if you look directly up at the sky.
E.g. during January, Gemini appears at the zenith.
Rise and fall of sea levels caused by the Moon's gravitational influence.
Phases of the Moon
Monthly progression of changes in the Moon's appearance, caused by different portions of Moon's sunlit side seen from Earth.
When the Full Moon passes into Earth's shadow and has an orange-ish colour. Safe to watch.
When the shadow of the New Moon is in between Earth and the Sun. UNSAFE TO WATCH.
Why do we have seasons?
We have seasons because of the Earth's orbit around the Sun and it's tilt.
E.g. When the northern hemisphere is tilted toward the Sun, it will be Summer, and Winter in the southern hemisphere.
A celestial object that orbits one or more stars (and is not a star itself), is spherical, and does not share it's orbit with another planet.
E.g. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
The Sun and objects that orbit the Sun.
The movement of an object in the sky (usually a planet) that moves from east to west, rather than west to east.
Astronomical Unit (AU)
A unit of measuring the distance between the Sun and Earth, which is 1 AU. 1 AU = 150 million km, or 1.5 x 10^12 km.
E.g. The orbital radius from the Sun to Neptune is 30 AU.
The distance from the Sun to an object orbiting it (usually a planet).
E.g. Mercury orbital radius from the Sun is 0.39 AU.
A model of the Solar System suggesting that the Earth was in the center and everything else (including the Sun) orbited it in perfect circles. Based on the work of Ptolemy.
A model of the Solar System suggesting that the Sun is in the center, and everything else orbits it in perfect circles. Created by Nicolaus Copernicus, but was revised by Johannes Kepler, who illustrated the planets' orbits as ellipses.
An object made up of rock, ice, and gas. They come from the Kuiper Belt or Oort cloud. When they come close to the Sun, it's radiation releases the particles, and it's wind pushes it away.
A small non-spherical object believed to be debris from the Solar System's formation. Most orbit the Sun in the Asteroid belt and vary in size.
A piece of rock moving through space.
A meteoroid that hits Earth's atmosphere and burns up.
A meteoroid that is large enough to pass Earth's atmosphere and reach the ground without being completely burned up.