1. light-years time as distance
Gretchen Mendoza
Rhetoric & Information Design
Instructor Miso Kim
Project 1: Time
a rhetorical argument
4 March 2010

2. what is a light-year?
A light-year is a unit of length, equal to just under 10
trillion kilometres, or 5.9 trillion miles. As defined by
the International Astronomical Union, a light-year is the
distance that light travels in a vacuum in one Julian year.
The light-year is often used to measure distances to stars
and other distances on a galactic scale, especially in non- When you search for “light-year” on
specialist and popular science publications. Googlethe first entry is a Wikipedia
page showcases this diagram.
Outer shell is one light year from Sun
and left yellow line is Comet 1910 A1’s
orbit. Inner shell is one light month.

3. who cares?
The concept of light-years, a measure of time based
on distance traveled, is a very difficult one to compre-
hend. The scale is beyond human comprehension in
many ways, and it tires the mind.
Explaining time on this scale is a long-term effort.
Many artists, philosophers, educators, scientists
have tried to put space-time into perspective before.
Eames Power of Ten
subliminal inspiration

4. where might this information be made available?
Classrooms, science exhibits, everyday articles.

5. why ?
The space-time continuum is difficult to grasp.
It needs distillation, and an improved sense
of relevance on an earthly, human scale.

6. how ?
A two dimensional representation or “map” of
light delays as we experience them on earth would
simplify the concept of time over great distances.
By basing the perspective largely on human-scale
terms, the phenomenon appears in a “grammar”
we recognize, instead of science jargon.

10. LIGHT-TIME
because of the scale and vastness in space
we must measure distance in terms of
how long it takes light to travel.
on the human scale, light is instant,
but on the cosmic scale, the light we see
is a snapshot of light that shone in the past.
HOW OLD IS YOUR LIGHT?
nearest starlight delay
4 LIGHT-YEARS
the nearest star, proxima centauri = xxxx miles away
sunlight
8.3 LIGHT-MINUTES
the sun = 93 million miles away
moonlight
1.3 LIGHT-SECONDS
the moon = 240,000 miles away
the speed of light
INSTANT
at 186,000 miles per second

11. 1 sec (moon)
8 min (sun)
1 hour
(saturn)
1 day
1 year

12. 126,144,000 light-seconds 3,600 light-seconds 480 light-seconds 1.3 light-seconds instant
starlight 4.2 light-years light on
the nearest star proxima centauri = 24.8 trillion miles away
earth
planetary light 1 light-hour
saturn = 755.6 million miles away the speed of light =
sunlight 8.3 light-minutes 186,000 miles
per second
the age
93 million miles away
moonlight
The further out we look into space, All light seems instant to us on earth. 240,000 miles away
the farther back we see into time.
But because of the scale and vastness in space, we must measure distance in
of light
terms of how long it takes light to travel. On the human scale, light is instant,
but on the cosmic scale, the light we see is a snapshot of light in the past.
This phenomenon is known as the space-time continuum.
when we see it on earth
undergraduate degree 4 years lunch break 1 hour average American shower 8 minutes cell phone delay 1 second
Gretchen Mendoza Rhetoric + Information Design Spring 2010 not to scale

13. 126,144,000 light-seco
starlight 4.2 light-year
the nearest star proxima centauri = 24.8 trillion
the age The further out we look in
the farther back we see in
of light
when we see it on earth
undergraduate degree 4 years
Gretchen Mendoza Rhetoric + Information Design Spring 2010

14. 126,144,000 light-seconds
starlight 4.2 light-years
the nearest star proxima centauri = 24.8 trillion miles away
The further out we look into space, All light seems inst
the farther back we see into time.
But because of the scale and
terms of how long it takes lig
but on the cosmic scale, the l
This phenomenon is known
undergraduate degree 4 years

15. All light seems instant to us on earth.
But because of the scale and vastness in space, we must measure distance in
terms of how long it takes light to travel. On the human scale, light is instant,
but on the cosmic scale, the light we see is a snapshot of light in the past.
This phenomenon is known as the space-time continuum.

16. 3,600 light-seconds 480 light-seconds
planetary light 1 light-hour
saturn = 755.6 million miles away
sunlight 8.3 light-minutes
93 million miles away
lunch break 1 hour average American shower 8 minutes

17. 480 light-seconds 1.3 light-seconds instant
light on
earth
the speed of light =
sunlight 8.3 light-minutes 186,000 miles
per second
93 million miles away
moonlight
240,000 miles away
average American shower 8 minutes cell phone delay 1 second
not to scale

18. sources
Photo sources:
http://www.atlasoftheuniverse.com/milkyway2.jpg
2D diagram sources:
http://www.rlrouse.com/astronomy/light-year.html
http://map.gsfc.nasa.gov/media/091057/091057_diagram.png
Text sources:
http://en.wikipedia.org/wiki/Light-year
http://www.jimloy.com/astro/ly.htm
http://emptv.com/images/spacetime-diagram-world-line.png
Video sources:
Wellesley Astronomy Professor: Light-year (E=mc2)
Science on the Brain: What is a lightyear?
Eames’ Power of Ten
Magnitude
http://stargazing.suite101.com/article.cfm/solar_system_magnitude_scale
Distance/Scale
http://www.freemars.org/jeff/planets/Luna/Luna.htm