Download Distance Light travels in ONE year!

http://www.youtube.com/watch?v=OtaWkLFfevc
Where are we?
Distances of the Universe
Metric System: 1000m = 1km
Astronomical Unit (AU): Earth to sun = 1 AU (1.496 x 1011
m)
***Light Year***: Distance Light
travels in ONE year! (9.46 x 1012 km)
Parsec: parallax-second (3.08 × 1016 m)
A Light Year
• Measure of DISTANCE!!
• Distance light travels in one year through space
• Light travels at a speed of 3x10 8m/s
• If a planet is 4 light years away, it takes all light waves 4
years to get to that planet.
• If it takes light 10 years to get from one star to Earth,
that star is 10 light years away.
• If satellite is put on a planet located 1 light year away, a
radio signal would take 2 years to be sent, reflected,
and returned to Earth.
Superman can fly at light speed! The
planet Krypton orbits the star Polaris
which is 433.8 Light years from Earth,
How long would it take superman to fly
home?
A. 433.8 yrs
B. 433.8 days
C. 433.8 hrs
Looking into the past
Everything we see in the sky is in the past! Why?
Object
Light travel time
Moon
1.3 seconds
Sun
8 min 19 seconds
Sirius
8.5 years
(meaning what?)
2.3 million years
Andromeda
Galaxy
A picture of the Andromeda galaxy reveals what it looked like 2.3 million
years ago. How long would we have to wait to see what the galaxy looks
like right now?
A spacecraft leaves Earth for a distant planet and is
traveling at the speed of light. Upon arrival, the
space ship sends a radio signal back to Earth. The
signal is received 10 years after the DEPARTURE of
the space craft from Earth. How far away is the
other planet?
A: 5 ly
B: 10 ly
C: 20 ly
D: 15 ly
Imagine that you simultaneously receive satellite
transmissions of two pictures of two aliens orbiting
two different stars at different distances from Earth. Both
aliens are celebrating their 14th birthdays in the pictures.
Which of the following situations is possible at the
moment you receive the pictures?
A. Both aliens are the same age but at different distances.
B. The aliens are different ages but at the same distance.
C. The alien closer to Earth is actually the older of the two.
D. The alien farther from Earth is actually the older
of the two.