The EARTH is 93 Million Miles

from the SUN.

Distances in our Solar System are measured in ASTRONOMICAL UNITS (AU).

Topic: Light YearsEssential Question: How do scientists use light years to measure distances in our universe?

Astronomical Unit (AU)•Used to measure distances in our solar system• about 93 million miles which is the Earth to the Sun

IS A MEASURE OF

A LIGHT YEAR IS THE DISTANCE

LIGHT TRAVELS IN ONE YEAR!!!

Topic: Light YearsEssential Question: How do scientists use light years to measure distances in our universe?

Light Year•The distance that light travels in one year•Light travels at the fastest speed known in the universe•It can go around the Earth 7 times in 1 second!

Scientist use LIGHT YEARS because STARS are too far away from each

other to use…

Topic: Light YearsEssential Question: How do scientists use light years to measure distances in our universe?

Light yearScientists use light years because stars are too far away to use: meters, kilometers, AU (Astronomical Unit)

•One light year is 10x1016 meters long•That’s 5.8 trillion miles!

One LIGHT YEAR is

or

1 year 1 year 1 year 1 year 1 year

1 x 1016 1 x 1016 1 x 10161 x 1016 1 x 1016

Five Light Years = 5 x 1016 meters

43 Light Years from EARTH

It takes 43 (human) years for the light from

this star to reach earth!

•By the time you see the light 43 years have passed.•The light was created before most of your parents were born.

Topic: Light YearsEssential Question: How do scientists use light years to measure distances in our universe?

If a star is 43 light years away, that means light has been traveling 43 years from that star to Earth

That means this light started traveling before most of your parents were born