The Solar System & Beyond

Chapter 21

The Sun

• The closest star

• Center of our universe

• Made up of hydrogen and helium atoms that produce light and heat through nuclear fusion

Measuring Space Distance• Light Year – the

distance that light travels in one year – One light year is

about 9.46trillion kilometers

– Light travels at 300,000 km/s

– The farthest objects we can observe are more than 10 billion light years away

Astronomical Units measure distance between the earth and a star

Expanding Universe• Astronomical Units

(AU) are a unit of measurement used to calculate the distance between the Earth and the sun as well as other stars

• Earth is 1 AU from the sun and Mars is 1.54 AU from the sun

Mercury• The closest

terrestrial planet to the sun

• Has a diameter of 4,879 km

• Its revolution around the sun takes 88 days

• 3.2 light minutes from the sun

• Temperature range -127ºC to 427ºC

Venus• 2nd terrestrial planet

from the sun• Spins clockwise on

its axis (retrograde)• Has the densest

atmosphere• 6.0 light minutes

from the sun• One year revolution

is 224 days long • Temperature 464 C

EarthEarth

• 3rd Terrestrial Planet From the Sun

• Only one that supports life

• 8.3 light minutes from the sun

• 12,756 km wide• Revolution 365

days

Mars• 4th planet from the

sun

• 6,794 km in diameter

• Nicknamed the red planet

• Temperatures range from -123 C to 37 C

• 12.7 light minutes from the sun

Jupiter• Largest gas giant

• Diameter: 142,984 km

• Revolution 11 ¾ Earth years

• Temperature -110 C

• Radiates more energy than it receives. Distance from sun 43.3 light minutes

Saturn

• Winds blow at 1000 mph at its equator

• Width is 120,536 km in diameter

• Revolution 29 Earth years and 155 days

• Temperature -140 C• Has Icy rings• Light from the sun

reaches here in 1.3 light hours

Uranus• Spins on its side, its

poles, possibly due to planet collision

• Diameter 51,118 km• Temperature -195º C• One revolution is 83

Earth years and 273 days

• 2.7 light hours from the sun

Neptune

• Has belts of visible clouds

• Diameter 49,528km• 4.2 light hours from

the sun• Has thermal energy

center that warms the planet like Jupiter and Neptune

• Revolution 163 Earth years

• Temperature -200 C

Pluto ?????• Farthest from the

sun, Bizarre Orbit• Demoted from planet

August 2006• Diameter 2,390 km• Temperature -225 C• Revolution every 248

Earth Years• 5.4 light hours from

the sun