Astronomer's Tools Discovery Through Technology. Humans have created many tools to help explain the mysteries of the universe. Sun dials help tell time. - ppt download
What's bigger: LD, AU or Light-Year? | Star Walk
Solar System - Wikipedia
What Are the Solar System Planets in Order? | HowStuffWorks
Have we made an object that could travel 1% the speed of light?
Terrestrial Planets: Definition & facts | Space
What Is a Light-Year? | NASA Space Place – NASA Science for Kids
What is a Light Year? | Picture Encyclopedia of Astronomy
How Many Years are in a Light Year? | The Speed of Light - YouTube
How Far is the Sun From Earth? | Distance, KM, Time Takes & Facts
What is a light-year? | prior probability
What is a light year, and how many Earth years are equivalent to a light year? - Quora
How far is a light-year? Plus, distances in space
Light Year - Unit, Value of One Light Year, Light Year Conversion, FAQs
How far is a light-year? Plus, distances in space
How big is Solar System in terms of light-years? - Quora
eSky: Light Year
time - How long did it take for the universe to become 1 one light year? - Physics Stack Exchange
What Is a Light-Year? | NASA Space Place – NASA Science for Kids
Observable universe - Wikipedia
What is a light-year? | Space
How much time will a car take to go 1 light year if the car goes 100 kilometres per hour? - Quora
How Far Does Light Travel in a Year? - Universe Today
How Long Would it Take to Walk a Light-Year?
