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 rocky, compact surface like the
Earth's. Jupiter, Saturn, Uranus, and Neptune are known as Jovian, or
Jupiter-like, planets because they are gigantic planets when compared
with Earth and have a gaseous nature like Jupiter's. Jovian planets are
sometimes called the gas giants. Pluto is not a member of either group.
Its composition is unknown, but it is probably composed mostly of rock,
ice, and frozen gases.
Developing the Activity
Present the following scenario to students:
Since humankind wants to know more about each of our
planetary neighbors, we need to plan our travel to the planets. Select
one terrestrial planet and one Jovian planet. Plan trips to the two
planets and to Pluto. Describe the speed of your spacecraft as well as
the time required to reach the planet, stay one Earth year to explore
it, and return to Earth. You may assume that advances will be made in
the development of spacecraft and that speeds up to 50,000 miles per
hour will be possible.
As a class, you will need to determine a Launch Day for all
missions. Based upon that Launch Day, on what date will you arrive at
the targeted planet? On what date will you return from each mission?
These questions will require that students convert such time
intervals as 10.2 years into years and days. When the conversion
results in a part of a day, round the value to the nearest day.
Students may not be familiar with thinking about a date in the year as
having an ordinal value in relation to the year; for example, 1 July is
the 183rd day of the year. Locate a reference calendar where the
ordinal value is given along with the date. Remind students they may
not necessarily be beginning with 1 January, however. Launch could be
on any day of the year. Since the year 2008 is a leap year, students
need to use 366 days for that year as well as other leap years spent
traveling to other planets.
Each member of the mission team should write about one of the
trips to a planet. The description should include the launch date, the
destination, the speed of travel, the time to reach the planet, the
date of arrival, and the date the crew returned to Earth.
To this point in the lesson, students have been considering
space travel from the perspective of what happens to the space traveler
on the journey. But while the space travelers are visiting distant
planets, life continues on its usual course at home on planet Earth.
Students should be familiar with the aspect of all travel from their
previous experiences. While they are away from home, life goes on; on
their return, they need time to catch up on all the news and events.
Occasionally, an event occurs while they are gone that has a profound
effect on them when they return.
Extending the Activity
Return the students to their mission teams. Tell them to imagine
that their team was actually sent on a mission to their selected
terrestrial planet. They know their launch data and have computed the
duration of their trip and the date of their return. Although NASA kept
the crew members posted on the news, they have missed many important
events, both personal and public.
Each mission team serves as the ground crew for a
space-traveling counterpart. The ground crew's task is to debrief the
astronauts on their return to Earth.
Each ground crew makes a list of important events that the
astronaut crew should know about on its return. Of course, the names
and some of the events will be fictitious, but they should be plausible
for the time that passed on the journey. Be certain to include the
results of regularly occurring events. Such personal events as
graduations for family members should be mentioned, too. Sports events,
such as the Olympics, the Super Bowl, and the World Series, maybe
important events for some students.
Closing the Activity
Students present the briefings they have written for the
returning astronauts. These reports could take many forms. Some mission
teams may make time lines. Others may present their briefing as a
newscast. They might use technology to support their presentation.
Another team member may make a scrapbook. Do not place limits on their
All students should take time to reflect on the mathematics of
this lesson. The calendar, the time conversions, the distances in
space, and the speeds required to complete space travel are all
important concepts for students to think about as they construct their
understanding of the world and the mathematics that describes it.