P2.5+ Space Flashcards
Year 9 (34 cards)
What is an orbit?
A repeated path an object takes around another object.
What is the order of planets from the Sun?
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
What are the terrestrial (rocky) planets?
Mercury, Venus, Earth, Mars.
What are the gas giants?
Jupiter, Saturn, Uranus, Neptune.
How long does the Earth take to orbit the Sun?
365.25 days.
How long does the Moon take to orbit the Earth?
29.5 days.
How long does the Earth take to spin once on its axis?
24 hours.
What causes day and night?
The Earth’s rotation on its axis.
What causes the seasons?
The Earth’s tilted axis — the Northern Hemisphere is tilted closer to the Sun in summer and away in winter.
What is an axis?
An invisible straight line around which an object rotates or spins.
What is a lunar month?
The time between one new moon and the next — about 29.5 days.
How many phases of the Moon are there?
8 phases.
Does the Moon make its own light?
No, it reflects light from the Sun.
Why does the Moon’s appearance change?
Because different parts are lit up as it orbits the Earth.
What does non-luminous mean?
An object that does not produce its own light.
What is weight?
The downward force of an object with mass in a gravitational field.
What is mass?
The amount of matter in an object.
What does gravity act between?
All objects with mass.
What affects the strength of gravity between two objects?
Their masses and the distance between them
What causes planets to orbit stars and moons to orbit planets?
Gravity
What is the equation for weight?
Weight = mass × gravitational field strength.
What is Earth’s gravitational field strength?
10 N/kg (or more precisely 9.8 N/kg).
Why does your weight change on different planets?
Because gravitational field strength is different, but your mass stays the same.
What is a star?
A celestial body that produces heat and light.
