Astronomical Units & Light Years Project

Distance in Space

• An

ellipse

is an oval-shaped path.

An

astronomical unit (AU)

is the average distance between Earth and the sun; it is about 150 million kilometers.

Light-year

The distance that light travels in one year, about 9.5 trillion kilometers or 63,240 AU

The speed of light is the fastest speed that could EVER be achieved.

The speed of light is 300,000 km per SECOND!!

(That’s 186,000 miles per second) Light takes 2 seconds to reach the Earth from the moon - it takes it 8 minutes to reach the Earth from the Sun

If you were in a spaceship that travelled at the speed of light and you started a journey from the Sun it would take: about 3 minutes to reach Mercury, 5 minutes to reach Venus, 8 minutes to reach the Earth, 5 1 / 2 hours to reach Pluto, 4 years to reach the next star, 5000 years to reach the edge of the galaxy, 50,000 years to reach the next galaxy, 500,000 years to reach the next Cluster!!

Real rockets don’t travel at the speed of light, they travel MUCH slower.

The Apollo missions took 4 days to reach the moon - at the speed of light it would have taken 2 seconds!!

These rockets were travelling roughly 200,000 times slower than light.

At this speed it would take 125 YEARS to get to Pluto!

The Astronomical Unit, au

Earth The Earth’s orbit around the sun is not circular – it is elliptical Sun

The Astronomical Unit, au

Earth 1 au The average radius of the orbit is defined as one astronomical unit, au Sun

The Astronomical Unit, au

Earth 1 au

1 au = 1.49 x 10

11

m

about 150 million kilometers Sun

A model of our Solar System

•You will make a scale model with proportional astronomical units with respect to the sun •Make Earth 5 mm in diameter and the rest of the planets to scale with respect to the Earth •Use the internet and/or you Prentice Hall book to determine the colors and appearance of each planet

Table #1: Planet Distances Planets

Mercury Venus Earth Mars Asteroid Belt Jupiter Saturn Uranus Neptune Pluto

Distance from the edge of the Sun in AU

.39

= 3.9 cm .72

1.0

1.5

2.5-2.8

5.2

9.2

19.2

30.0

39.4

1 AU = 10 cm 0.39 AU x 10 cm 1 1 AU 0.39 AU = 3.9 cm Measure from the outer edge of the sun to the leading edge of the planet

Table #2: Planet Diameters Planets

Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto

Diameter (mm)

2.0 mm = 1 cm 1 10 mm 2.0

4.75

= 0.2 cm 5.0

2.65

56.0

47.0

20.0

19.0

1.0

2.0 mm = 0.2 cm

10 millimeters 1 centimeter

7.2 centimeters 3.9 centimeters Mercury Venus