Transcript Light Years - Cloudfront.net

http://janus.astro.umd.edu/astro/distance/
 If
you could travel to the closest
star from the sun in a car traveling
60 mph, how long would it take
you to get there?
• http://janus.astro.umd.edu/astro/distance/
48
million years

If you could travel to the closest star
from the Earth in a space shuttle at
18,000 mph, how long would it take
you to get there?

Like any other object in low-Earth orbit,
a Space Shuttle must reach speeds of
about 17,500 miles per hour (28,000
kilometers per hour) to remain in orbit.
160,000
years
 If
you ride on a beam of light, how
long would it take you to get there? It
travels 300,000,000 m/s
• http://janus.astro.umd.edu/astro/distance/
4.29
years
Why do we use Light Years?
Because distances in space are too vast
(big), miles and kilometers are too small
to be used.
 Scientists measure the distances in
space outside our solar system in light
years (ly)

The Milky Way is
the galaxy in which
the Solar System is
located.
The Milky Way Galaxy
is about 100,000 light
years across
https://www.youtube.com/watch
?v=bhofN1xX6u0
Older one
http://www.youtube.com/watch?v=0fKBh
vDjuy0&feature=player_embedded
What is a Light Year?
One light-year is the DISTANCE that
light travels in one year
If we are going to find out
HOW FAR a Light Year is,
we need to know two things…
1.
The speed of light, measured in meters
per second and
2.
The number of seconds in a year
What’s the fastest speed
in the universe?
- The Speed of Light
What is the speed of light? (abbreviated “c”)
300,000,000 meters per second or 3 X 108 m/s
How Many Seconds in a Year?
60 seconds per minute
X 60
minutes per hour
X 24
hours per day
X 365.25
days per year
31.55 million
=
the number of seconds per year
So How Far is a Light Year?
9,500,000,000,000,000 meters.
This said out loud is..
That’s Nine Quadrillion, Five Hundred Trillion Meters
What is this in scientific
notation?
9,500,000,000,000,000 meters.
In scientific notation, this is
9.5 x 1015 m
Practice!
Location
Distance from the Earth
Standard Form
Proxima Centauri
4.29 ly
Center of the Milky
Way
Andromeda
Coma Cluster of
Galaxies
Edge of the
observable Universe
Scientific Notation
2.99 x 104 ly
2,490,000 ly
3.34 x108 ly
14,900,000,000 ly
More Practice!
Location
Distance from the Sun
Standard Form
Mercury
Scientific Notation
57,910,000 km
Earth
1.496 x 108 km
Mars
2.279 x 108 km
Saturn
1,426,730,000 km
Pluto
5,906,380,000 km