Transcript Astronomical Units & Lightyears Project (Part III)

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,
51/2 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
Sun
The average radius of the
orbit is defined as
one astronomical unit, au
The Astronomical Unit, au
Earth
1 au
1 au = 1.49 x 1011m
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
Distance from the
edge of the Sun in AU
.39 = 3.9 cm
Venus
Earth
Mars
Asteroid Belt
.72
1.0
1.5
2.5-2.8
Jupiter
Saturn
Uranus
5.2
9.2
19.2
Neptune
Pluto
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
Diameter (mm)
Planets
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
2.0 = 0.2 cm
4.75
5.0
2.65
56.0
47.0
20.0
19.0
1.0
2.0 mm = 1 cm
1
10 mm
2.0 mm = 0.2 cm
10 millimeters

1 centimeter
7.2 centimeters
3.9 centimeters
Venus
Mercury