Science Test Flashcards
What does it mean for a planet to revolve
The movement of one object around another.
- every planet in the solar system orbits the sun
- farther the planet, the longer it takes to revolve
- each planet besides Mercury and Venus has a moon that revolves around the planet
What does it mean for a planet to rotate
Earth’s full rotation is one day and each planet rotates on its axis
Earths and moons orbit
Moon orbits earth at an angle
How planets stay in their orbit
- gravity from other planets and objects
- inertia
- gravity attracts all objects toward each other
Earths seasons
- they are all caused by Earth’s axis and it’s revolution around the sun
- When earth is tilted toward the sun (top of earth is closest to sun) it’s summer in the northern Hemisphere and winter in the southern hemisphere
- When earth is tilted away the sun (bottom of earth is closest to sun) it’s summer in the Southern Hemisphere and winter in the northern hemisphere
- warm around equator
Soltices
Either of the two days a year where the sun reaches its greatest distance North or South of the equator
- When the sun reaches its greatest distance north, it’s the summer solstice in the Northern Hemisphere and the winer solstice in the Southern Hemisphere
- When the sun reaches its greatest distance south, it’s the summer solstice in the Northern Hemisphere and the winer solstice in the Northern Hemisphere
- Winter solstices are the shortest day & longest night of the year
- Summer solstices are the longest day & shortest night of the year
- there are 2 solstices a year
Mass
Amount of matter in an object
- If your mass is 100 pounds on earth it stays 100 pounds on every planet.
Weight
The measure of the force of gravity on an object
- Your weight changes by the amount of gravity is acted on you ( if you jump up and go down your weight is more
- your weight changes on different planets because there are different amounts of gravity on different planets
Force of gravity
How much force is exerted on bringing two objects closer to each other
- more mass an object has = more gravity and greater force of gravity
- shorter distance = stronger force of gravity
The sun
Has more mass than other starts but not as much volume
- ordinary mid-star
- it has more mass so it exerts more heat and won’t burn out quickly
Solar and lunar esclipses
Doesn’t occur every month because the earth and moon have to be aligned in a certain way
- Lunar Eclipse: occurs during a full moon when earth is directly between sun & moon
- Solar Eclipse: occurs during a new moon when moon passes directly between earth and sun causing moon to cast shadow on Earth and blocking Suns light
Planets requirements to be planet
- Must orbit sun
- must have cleared out the region of orbit
- must be round
Planets order
- Mercury/ smallest planet
- Venus/ hottest planet
- Earth/ supports life
- Mars/ red planet
- Jupiter/ largest planet
- Saturn/ rings
- Uranus/ sideways
- Neptune/ farthest
Astronomical unit
1AU = 150,000 km
- AU is used over miles or kilometers bc distance in space are large so they need a larger System to measure
- Light years: distance to measure distance
Inner planets
Mercury, Venus, earth, Mars
- Rock surfaces
- closest to sun
- smallest planets
