1. Light Year This is a DISTANCE not an amount of TIME This is a DISTANCE not an amount of TIME EX: 3 Miles is a distance, 3 Years is a time EX: 3 Miles is a distance, 3 Years is a time Used to represent extremely LARGE distance in space Used to represent extremely LARGE distance in space Remember, Light is a Transverse Wave – and all waves travel, they don’t just appear Remember, Light is a Transverse Wave – and all waves travel, they don’t just appear

2. So how far is it? This distance is very large – it’s hard for the mind to understand how far this is This distance is very large – it’s hard for the mind to understand how far this is Speed of Light = 300,000 km/sec Speed of Light = 300,000 km/sec That’s about 18,000,000 km/min That’s about 18,000,000 km/min Oh that’s right we don’t like the metric system in America – let’s look at that in mph Oh that’s right we don’t like the metric system in America – let’s look at that in mph

3. So how far is it? Speed of light is about 186,000 miles/sec Speed of light is about 186,000 miles/sec That is about 671,000,000 miles per hour That is about 671,000,000 miles per hour

4. So how far is it? Now that you know how fast light travels it time think about distance Now that you know how fast light travels it time think about distance If we look at how far light would travel for ONE full year – that distance is a Light Year! If we look at how far light would travel for ONE full year – that distance is a Light Year!

5. So how far is it? The total distance light travels in one full year is about: 9,460,000,000,000 km (9.46 trillion km) The total distance light travels in one full year is about: 9,460,000,000,000 km (9.46 trillion km) In terms of miles that is about: 5,800,000,000,000 miles (5.80 trillion miles) In terms of miles that is about: 5,800,000,000,000 miles (5.80 trillion miles)

6. An example close to home… So how far is that distance of a light year… really. So how far is that distance of a light year… really. EX: it is about 370,000 km from the Earth to the Moon. If you could walk from the Earth to the Moon, how many times would you have to go that distance to equal a light year? EX: it is about 370,000 km from the Earth to the Moon. If you could walk from the Earth to the Moon, how many times would you have to go that distance to equal a light year? ANSWER: about 12 MILLION times back and forth from the Earth to the Moon! ANSWER: about 12 MILLION times back and forth from the Earth to the Moon!