Transcript Scale of the Universe

This stuff is FAR!
Sizes of things
 Earth diameter: 13,462 Km
 Mars diameter: 6,800 Km
 About ½ Earth
 Jupiter diameter: 142,984
 10+ times the Earth
 1,000+ Earths would fit inside
 Sun diameter: 1.4 million kilometers
 109 times Earth, almost 10 times Jupiter
 1,000,000 Earths would fit inside
Distance to the Sun
 Earth is 149,597,871 Km from the Sun
 92,955,807 miles
 This distance is 1 astronomical unit
 AU
Astronomical Unit
 Mercury is .4 AU from the Sun
 Venus is 0.72 AU
 Mars is 1.52 AU
 Jupiter is 5.2 AU
 Saturn is 9.5 AU
 Uranus is 19.6 AU
 Neptune is 30 AU
 Kuiper Belt is 30 to 50 AU
 Oort Cloud is 50,000 to 100,000 AU!
Edge of the solar system
 Heliosphere - The bubble in the interstellar medium
of space caused by the Sun’s wind
Beyond the solar system
 Beyond the solar system,
the astronomical unit
becomes too small
 Like measuring distance
around USA in millimeters
 Need a bigger unit of
measure – the Light Year
(LY)
 Light Year – distance light
can travel in one year
Beyond the solar system
 Oort Cloud is about 2 LY in diameter
 Nearest star, Proxima Centauri, is 4.22 LY
 Center of Milky Way is 26,000 LY
 Milky way is 100,000 LY across
 Nearest Galaxy, Andromeda, is 2.5 million LY away
 Voyager 1 will take 18,000 years to go 1 LY
How do we know this?
 Measurement to distant objects is done with
trigonometry
 Parallax - difference in the apparent position of an
object viewed along two different lines of sight
Beyond the Light Year
 Parsec – uses parallax
 Parallax of 1 arcsecond
 3.26 LY
 pc
Beyond the Light Year
 Parsec is for really big distances
 Proxima Centauri = 1.29 parsecs
 Galaxy RXJ1242-11 = 200 million pc
 Edge of observable universe 14 billion pc
This stuff is FAR!