Educational Insights GeoSafari ESP 5287-UK Guide page 3

The Solar System Model
Turn on the model and dim the room lights. You'll be able to see the sun's light shining
on the planets better in a darkened room. The support rods and tower will also blend into
the background.
Solar System Basics
The sun is at the center of our solar system. It gives us heat and light.
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Earth is one of 8 planets in our solar system.
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The inner planets (Mercury, Venus, Earth, Mars) are made of rocks and metals; they are the
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"terrestrial planets."
The outer planets (Jupiter, Saturn, Uranus, Neptune) are made mostly of gases, liquid, and
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ice; these are the "gas giants."
The planets move, or revolve, around the sun constantly.
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The planets move in patterns called orbits. The shape of an orbit is not perfectly circular but
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like a slightly squished circle.
All the planets move in the same direction and on the same plane ("slice of space") as they
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orbit the sun.
One "year" is the time it takes a planet to orbit the sun.
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Each planet also rotates, or spins, as it revolves around the sun.
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One "day" is the time it takes a planet to rotate all the way around.
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The planets travel around the sun at different speeds. (In this model, the inner planets move
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faster as a group, while the outer planets move more slowly as a group.)
The planets follow very regular patterns as they travel around the sun. A planet's location
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changes from day to day, but scientists can calculate where each planet will be at any given
time using mathematics.
Model Not to Scale
Keep in mind that home or classroom solar system models cannot show planet sizes or distances
to scale. This means that the planets' sizes and distances relative to one another are not what
they would be in real life.
For example, the sun must be shown much smaller, compared to the planets, than it actually is.
In reality, the sun is about 108 times the Earth's diameter and is about 1 million times greater in
volume—a million Earths could fit inside the sun!
The distance between planets is also hard to show on a model. In reality, the planets are very
small compared to the distances between them. Suppose, for example, our model-sized Neptune
were shown a correct relative distance from the sun (which would be huge if shown to scale—
about 28 inches in diameter, or about as big as an adult bicycle tire). Neptune would need to be
1.4 miles (2322 meters) away. It would take you around a half hour to walk from the sun to the
edge of your solar system model!
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Planetary Features Chart
The Planetary Features Chart provides some basic information about the planets, including their
order, distance from the sun, size, and temperature.
Position Average "Year": Period
Diameter
Planet Symbol relative distance of time to
at equator
to sun from sun orbit sun
36,000,000 mi 3,032 mi
Mercury 1st 88 Earth days
(58,000,000 km) (4,879 km)
67,000,000 mi 7,521 mi
Venus 2nd 225 Earth days
(108,000,000 km) (12,104 km)
93,000,000 mi 7,918 mi
Earth 3rd 365.25 Earth days
(150,000,000 km) (12,742 km)
142,000,000 mi 4,212 mi 687 Earth days
Mars 4th
(228,000,000 km) (6,779 km) (1.88 Earth years)
88,881 mi
484,000,000 mi
Jupiter 5th (139,822 11.8 Earth years
(778,000,000 km)
km)
72,367 mi
886,000,000 mi
Saturn 6th (116,464 29.5 Earth years
(1,427,000,000 km)
km)
1,784,000,000 mi 31,518 mi
Uranus 7th 84 Earth years
(2,871,000,000 km) (50,724 km)
2,795,000,000 mi 30,599 mi
Neptune 8th 164 Earth years
4,498,000,000 km) (49,244 km)
* Scientists are constantly discovering new planetary moons and space objects. For the most up-to-date information, check one of NASA's websites such as: https://
solarsystem.nasa.gov.
Planet Riddles
Use the Planetary Features Chart to help you solve these planet riddles!
My "day" is longer than my I am the biggest planet.
"year"! Who am I? I am so big that all the
other planets could fit
inside of me. Who am I?
I am the hottest planet. My We are the only two planets in
surface temperatures are so hot the solar system without any
that metals like lead would turn moons at all. Who are we?
into puddles. Who am I?
"Day": Time
Temperature
Average Atmosphere
it takes to
(min to max surface temperature
orbital (major Moons*
rotate on
for inner planets; effective
speed components)
temperature for outer planets)
axis
30 mi/sec
59 Earth days almost non-existent 0 -279 to 801 ºF (-173 to 427 ºC)
(48 km/sec)
carbon dioxide,
22 mi/sec nitrogen, and
243 Earth days 0 864 ºF (462 ºC)
(35 km/sec) clouds of sulfuric
acid
78% nitrogen, 21%
18.5 mi/sec oxygen, 1% argon,
24 hours 1 -126 to 136 ºF (-88 to 58 ºC)
(30 km/sec) carbon dioxide,
and trace gases
15 mi/sec carbon dioxide,
25 hours 2 -225 to +70 ºF (-153 to +20 ºC)
(24 km/sec) nitrogen, argon
8 mi/sec
10 hours hydrogen, helium 67 -234 ºF (-148 ºC)
(13 km/sec)
6 mi/sec
11 hours hydrogen, helium 62 -288 ºF (-178 ºC)
(10 km/sec)
4 mi/sec hydrogen, helium,
17 hours 27 -357 ºF (-216 ºC)
(7 km/sec) methane
3 mi/sec hydrogen, helium,
16 hours 14 -353 ºF (-214 ºC)
(5 km/sec) methane
The methane gas in our
atmosphere gives us a blue tint.
Which two planets are we?
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