How is a planet different from a star?
Planet doesn’t create its own light, Planet has weak source of energy, stars
have no solid surface, stars made up of gas, planets mix of solid & liquids,
planets smaller- less massive.
How many planets are known to exist?
8 major planets- (order closest to sun) Mercury, Venus, earth, mars,
Jupiter, Saturn, Uranus, Neptune
Solar system → sun, 8 planets, satellites of the planets, asteroids, comets, etc.
1. Why are so few craters on earth?
Dense atmosphere, craters usually burn in atmosphere
Most craters ever formed on Earth have been worn away by erosion (&
other geological processes)
mass of earth, only other planet to step on.
- smaller than earth, has polar cap, Olympus Mons (volcano)
on mars, → larger at any other mountain in solar system!
- is much larger than earth (10x diameter), largest in solar
system, (“The Great Red Spot”- hurricane type weather.), rotates
so fast clouds get stretched into bands, Jupiter has 2 moons (Io,
Europa), Io is volcanically active.
has ring, rings aren’t solid- atoms, rock, ice etc. make up
no cloud patterns looking at planet
- blue, has some clouds and bands, has a cyclonic storm
- recently designated a dwarf planet
(globe of gas)-Contains ⁿ/500
of matter in solar system,
100x larger in diameter than earth, 300,000x more massive.
Solar Neighborhood- (Milky Way Galaxy)
Light travels quickly!
186,000 miles/second, 7x’s around earth in 1 second, 1 foot in a
billionth of a second.
Light travel time:
Light second- 186,000 miles – 80% of distance to moon
Light hour- 700 million miles- Distance from sun to Saturn
Light year- 7 trillion miles- 1/4
distance to nearest star
Year- unit of time
Light year- unit of distance
Almost all visible
matter in universe are inside stars