Your Birthday on Another Planet

Brief Description

How old would I be, if I lived on another planet? In this classroom activity guide, explore when your next birthday would be if you lived on other planets in our Solar System.


 For each student (or team):


  • Thick paper

  • Photocopies of the Planetary Orbit Sheets numbered 1–24 (Attachments 1-6)

  • Glue

  • Scissors

  • Coloured pencils

  • Stapler or large clips for holding together a stack of 24 sheets of thick paper

  • Photocopies of the table of the planets’ revolution periods (Attachment 7)

  • Photocopies of the student handout ‘Your Birthday on Another Planet’ (Attachments 8-9)

Learning Objectives

In this activity students should learn to ask questions, interpret data, observe, identify variables, use logic, deduce, predict and develop motor skills. By assembling and using the Solar System flip book, students will realize that the four planets closest to the Sun (Mercury, Venus, Earth, Mars) revolve around the Sun in the same direction, albeit at different speeds. Students will use visual information, along with a table showing the orbital period of the planets in the Solar System, to deduce that the length of a ‘year’ isn’t the same from one planet to the next. They should conclude that their birthdays wouldn’t be celebrated at the same time on these planets as on Earth.

Background Information

All the planets in the Solar System revolve around the Sun in the same direction. The closer a planet is to the Sun, the faster it travels in its orbit and the less time it takes to complete a full trip around it. On a given planet, the ‘year’ is the period of time this planet takes to complete one orbit around the Sun. If we lived on another planet, our birthdays would occur more or less frequently depending on the planet’s revolution period (the time taken to complete one full trip around the Sun). On a few planets, we couldn’t even celebrate our first birthday because we wouldn’t live long enough for these planets time to complete a single full trip around the Sun!

Refer to the Table of Planets’ Period of Revolution (Attachment 7) for the distance from the Sun, orbital velocity and revolution period of each of the planets in our Solar System, and Pluto.

Full Activity Description

Gather the needed supplies and copy the quiz questions onto the board from the “Your Birthday on Another Planet” handout (Attachment 9).

Step 1

In front of the class, explain the steps for assembling the solar system flip book:

  • Glue the photocopies of the Planetary Orbit Sheets onto thick paper (Attachments 1-6).
  • On each of the illustrations numbered 1–24, colour the Sun and the four planets (Sun = yellow; Mercury = green; Venus = brown; Earth = blue; Mars = red).
  • Carefully cut out the illustrations along the dotted lines and stack them in order, with number 1 on top and number 24 at the bottom of the pile. Make sure that the images are placed in such a way that the numbers all appear in the same corner. Staple or pin the pile together in the spaces marked. (Image 1)

Step 2

Explain to students that once they’ve finished step one, they can observe the orbital movement of the planets by holding the flip book in one hand and quickly flipping through the pages with the other. The planets should revolve around the Sun counter-clockwise. To produce this effect, flip the pages from top to bottom. (Image 2)

Step 3

Once the students have flipped through its pages several times and properly observed planetary movement, pass around the student quiz ‘Your Birthday on Another Planet’ (Attachment 8-9).

Additional Information

Help students reach general conclusions about planetary movement: all planets revolve around the Sun in the same direction (counter-clockwise as seen from above the Earth’s North Pole) and that the farther away a planet is from the Sun, the longer it takes to complete one full trip around it.


Questions from the Student and Teacher handout, “Your Birthday on Another Planet” (Attachments 8-9):

  • In what direction do the planets move around the Sun? Answer by comparing this movement with the movement of the hands of a clock.

  • Which of the four planets travels fastest in its orbit around the Sun?

  • Which of the four planets travels most slowly in its orbit around the Sun?

  • You celebrate your birthday once every Earth year. How do we determine the length of a year?

  • Does a ‘year’ last the same amount of time on all of the planets?

  • If you lived on Mercury, would your birthday occur more or less often than on Earth?

  • What would your age be in Martian years if you lived on Mars?

  • At what age in Earth years could you celebrate your first birthday on Uranus? On Pluto?