Distance and Scale: Activity 1

ACTIVITY 1: THE PLANETS AND SCALE

Concepts:

size scales
geometry
graphing
analyzing data

INTRODUCTION

Our solar system has at its center, an average star we call the Sun. In orbit around the Sun are the nine planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto . There are also many comets, asteroids, satellites of the planets, and background dust in the solar system. The Sun contains 99.85% of all the matter in the Solar System. The planets, which condensed out of the same disk of material that formed the Sun, contain only 0.135% of the mass of the solar system. Jupiter contains more than twice the matter of all the other planets combined. Satellites of the planets, comets, asteroids, meteoroids, and the interplanetary medium constitute the remaining 0.015%.

Below is an image containing pictures (from spacecraft missions) of the nine planets (drawn to scale, that is, the relative sizes of one planet to another planet are correct).

The terrestrial planets are the four innermost planets in the solar system, Mercury, Venus, Earth and Mars. They are called terrestrial because they have a compact, rocky surface like the Earth's. The planets, Venus, Earth, and Mars have significant atmospheres while Mercury has almost none. Below is a close-up picture of the four terrestrial planets

Jupiter, Saturn, Uranus, and Neptune are known as the Jovian (Jupiter-like) planets , because they are all gigantic compared with Earth, and they have a gaseous nature like Jupiter's. The Jovian planets are also referred to as the gas giants, although some or all of them might have small solid cores.

Planetary Data:

The following table lists statistical information for the planets:

Orbital
Distance
(10^6 km) Radius
(km) Mass
(10^24 kg) Rotation
Period
(hours) # Moons Orbital
Period
(days) Density
(g/cm³)
Mercury 57.9 2439 .3302 1407.6 0 88. 5.43
Venus 108.2 6052 4.869 5832.5 0 224.7 5.25
Earth 149.6 6378 5.975 23.93 1 365.2 5.52
Mars 227.9 3393 0.6419 24.62 2 687. 3.95
Jupiter 778.3 71492 1898.6 9.92 16 4330.6 1.33
Saturn 1427 60268 568.5 10.5 18 10747. 0.69
Uranus 2869.6 25559 86.83 17.24 15 30588. 1.29
Neptune 4496.6 24766 102.43 16.11 8 59800. 1.64
Pluto 5913.5 1137 0.0125 153.1 1 90591. 2.03

	Orbital Distance (10^6 km)	Radius (km)	Mass (10^24 kg)	Rotation Period (hours)	# Moons	Orbital Period (days)	Density (g/cm³)
Mercury	57.9	2439	.3302	1407.6	0	88.	5.43
Venus	108.2	6052	4.869	5832.5	0	224.7	5.25
Earth	149.6	6378	5.975	23.93	1	365.2	5.52
Mars	227.9	3393	0.6419	24.62	2	687.	3.95
Jupiter	778.3	71492	1898.6	9.92	16	4330.6	1.33
Saturn	1427	60268	568.5	10.5	18	10747.	0.69
Uranus	2869.6	25559	86.83	17.24	15	30588.	1.29
Neptune	4496.6	24766	102.43	16.11	8	59800.	1.64
Pluto	5913.5	1137	0.0125	153.1	1	90591.	2.03

TASK A: Planet Sizes

ACTIVITIES:

Using the information from the above table (and images), please answer the following questions:

Q: Which planet is about the same size as the Earth?
A: Looking at the Radius column of the table, and the picture of the terrestrial planets, the answer is Venus .
Q: Which planet is just a little smaller, and has about the same Rotation Period as the Earth?
A: Mars . The period of rotation is the time it takes for the planet to spin 360 degrees on its axis--- in other words, it's the length of our day. A day on Mars would be just about as long as it is on the Earth.
Q: Which planet is the largest in the solar system?
A: Jupiter .
Q: Using the Radius column of the table, How many times larger than the Earth is Jupiter?
A: Jupiter's radius is 71492 km and the Earth's is 6378 km, making Jupiter more than 11 times larger than the Earth.

ADDITIONAL ACTIVITIES:

For an exercise that compares the sizes of the Earth and Sun , CLICK HERE .

To draw "scale" pictures of the planets, CLICK HERE .

TASK B: Planetary Orbits

To obtain background information on PLANETARY ORBITS, CLICK HERE .

The following diagram shows the approximate distance of the terrestrial planets to the Sun.

The following diagram shows the approximate distance of the Jovian planets to the Sun.

ACTIVITIES:

Using the Orbital Distance column in the table, make two graphs similar to the plots shown above:

The Orbital distance of the Terrestrial planets from the sun, and
The Orbital distance of the Jovian planets from the sun.

HINT: As in the example below, plot Orbital Distance in units of 10^6 km (that is, millions of kilometers).

Sample Plot:

Back to Homepage or Forward to Activity 2

This module was written by Eileen V. Ryan
NOAO/ Planetary Sciences, University of Arizona, Tucson AZ.

Return to SSI Education and Public Outreach Homepage

Galileo Solid State Imaging Team Leader: Dr. Michael J. S. Belton

The SSI Education and Public Outreach webpages were originally created and managed by Matthew Fishburn and Elizabeth Alvarez with significant assistance from Kelly Bender, Ross Beyer, Detrick Branston, Stephanie Lyons, Eileen Ryan, and Nalin Samarasinha.

Last updated: September 17, 1999, by Matthew Fishburn

Return to Project Galileo Homepage

Website Curator: Leslie Lowes

Website Feedback: Ron Baalke