AST101 Midterm 1

Size of universe

10 trucks containing sand, each grain is a galaxy in universe

Each grain is now also a small miniature truck that is full of sand, each grain is a star in the galaxy

The farther away you look

The farther back in time you look, because light takes time to travel

caracteristics of universe

Universe is expanding and cooling

Science is what

Epistemological system which objectively describes, and predicts the behaviour of the universe. It is testable

Caracteristics of planets’ orbits

• Orbit same plane (the Ecliptic plane)

• All orbit same direction

• Sun rotates same direction as planets orbit

• All orbits are elliptical

• Closer to the sun, faster orbit

Terrestrial planets carac

• Small

• Rocky

• Thin/No atmosphere

• Few moons

• Made of heavy elements (Denser than Jovian)

Mercury temps + probes visited

Super varying because no atmosphere

2 probes: 1 in the 70s and 1 in 2011-15

Venus carac

• size = earth

• Greenhouse effect and thick CO2 makes it super hot

• Rotates backwards

• Many probes and landers

Mars carac

• 25 deg tilt so seasons

• Many probes and landers

• Oceans evaporated

Jovian carac

Large

Gas and liquid

Many moons

Mostly light elements

Jupiter carac

Largest Planet

Thick gaseous atmosphere surrounding a giant ball of liquid hydrogen

Several probes visited

Faint rings

Saturn

Second largest

Structure = jupiter

Has spectacular rings

Many moons, more than 60 known to date

Several probes visited

Uranus carac

Coldest planet

Small rocky core

Thick water, ammonia,

Thick atmosphere with H2 and He

Rotation axis tilt 98deg

Thin rings and lot of moons

Neptune

Furthest planet

Structure = uranus

Rotation axis tilt 28 degrees

More surface features than uranus

Strongest winds in solar system: 2100 Kmh

Earths moon

Rocky

No atmo

Cratered

No geological activity

Jupiter moons

High ice content

Io most geologically active in solar system

Saturn moons

High ice content

Orbit same plane and direction as rings

Uranus moons

High ice content

Orbit same plane as Uranus rotates (97 degrees from ecliptic)

Neptune moons

14 known

Triton only one over 1000km in diameter

Triton: Orbit not same plane or direction as neptune’s rotation

Surface is frozen nitrogen

Dwarf planets

9 identified but could be many more

Ceres and Pluto visited by probes

Pluto has high ice content

Asteroid belt carc

A million asteroids larger than 1km diameter

Kuiper belt

Vast collection of small icy bodies beyond neptune

Comets carac

Smaller icy bodies from the outer solar system

Elliptical orbits

Emit tail when close to sun

Voyager probes carac

Alighment was perfect to visit all 4 jovians

Probes used each planets gravity to accelerate and change direction to the next planet

2 probes: voyager 1 and 2

Still operating, 20 light hours away from earth