Hawai'i Space Grant Consortium, Hawai'i Institute of Geophysics and Planetology, University of Hawai'i, 1996

How Old Are You?
Purpose

To understand the relationship between planetary orbits around the Sun and our measure of time.

Key Words

year

orbit

terrestrial planet

outer planet



Materials

"New" Age Chart

calculators

Background
Your birthday is actually a celebration of a trip made by Earth around the Sun one time. For each trip around our star we "age" one year... or at least that is how we humans express it. How "old" are you on the other eight planets in our solar system?

Procedure

1.
Figure your age in Earth days. [your age x 365]

2.
For the terrestrial planets, divide your age in Earth days by the number of Earth days in a planet's year. The answer is your "new" age.


Example for Mercury - for a person 20 years old on Earth:
20 x 365 = 7300 Earth days old
7300 / 88 (Earth days in Mercury's year) = 83
The 20 Earth-year-old person would be 83 years old on Mercury!

3.
For the outer planetrs, find the number of Earth days in each planet's year. Then divide your age in days by the number of Earth days in that planet's year. The answer is your "new" age.

Example for Jupiter - for a person 20 years old on Earth:
20 x 365 = 7300 Earth days old
12 Earth years x 365 Earth days/year = 4380 Earth days in one Jupiter year.
7300 / 4380 = 1.7
The 20 Earth-year-old person would be 1.7 years old on Jupiter!

4.
Follow the examples and fill in the blanks in the "New" Age Chart.



"New" Age Chart

Terrestrial PlanetsApproximate length of year:Your "new" age
Mercury88 Earth days
Venus225 Earth days
Earth365 Earth days
Mars687 Earth days


Outer PlanetsApproximate length of year:Your "new" age
Jupiter12 Earth years
Saturn29.5 Earth years
Uranus84 Earth years
Neptune165 Earth years
Pluto248 Earth years

Extension
Try it for the Sun -- What would your age be if the Sun takes 24 Earth days to rotate one time on its axis?


Return to Planetary Properties Activity Index.

Return to Hands-On Activities home page.
http://www.spacegrant.hawaii.edu/class_acts/