BecomeGalileo’s assistant

EdgarMartiarena

Introductory section and preparatory phase

• Short Description: Galileo was really confused about the geocentric

system. He was strongly convinced that sun is in the center of our planetary

system, so he was looking for undoubtedly evidences. Then he got the idea

to target his telescope to Venus. According to the geocentric system

(Ptolemy’s Model) it would not be possible to view all Venus in all phases,

but only as a meniscus. But, when he pointed his telescope at Venus he saw

all phases from full phase to new Venus. This was an ultimate evidence of

the heliocentric system. Furthermore, Galileo turned his telescope to Jupiter

revealing for the very first time the moons of Jupiter. These were the first

observed planets orbiting around another planet and not around Earth.

Imagine now being the assistant of Galileo recording all his observations

and claiming explanations. This is now your role. Become Galileo’s

assistant!

• Keywords: Heliocentric, geocentric, Venus, phases, Jupiter, Galileo.

• Target audience: Students studying Physics and Astronomy.

• Age range: 12-18 years old

• Context: Science Lab, Computers Lab, Internet Connection, Stellarium,

SalsaJ (both free software available on internet).

• Time required: 6 hours

Introductory section and preparatory phase

• Technical Requirements: Internet connection, appropriate software:

Stellarium, SalsaJ, connection to YouTube, Computers, video projector could

be useful.

• Author’s background: Knowledge of Physics, knowledge of Astronomy,

Stellarium, SalsaJ, use of internet. Geocentric model (Ptolemy’s model),

Heliocentric model, methodology of Galileo, finding of evidences for the

heliocentric model, solar system (use of Wikipedia can be useful).

• Connection with the curriculum: Strongly related to Astronomy (First, Second

and third Class of Junior High School), Physics (First, Second and Third Class

of Junior High School and First Class of High School). Partly related to

Philosophy and ideas of astronomers and philosophers (Ptolemy, Copernicus,

Galileo).

• Learning Objectives: Hands on learning, Inquiry based learning, ICT in

education, use of Open Science Resources, learn students to cooperate and act

as researchers.

• Guidance for preparation: Search in literature, bibliography, internet and other

sources, about ideas related to the geocentric and heliocentric model. Download

Stellarium and SalsaJ. Both Stellarium and SalsaJ are free on internet. Access

to archives providing images of Venus and the moons of Jupiter.

Pre-Experiment / Observation– Teaching Phase 1:

Questions Eliciting Activities – PROVOKE CURIOSITY

Teacher introduces students to the

geocentric model (Ptolemaic model).

Teacher can find useful information at:

http://en.wikipedia.org/wiki/Geocentric_model

while he can show this educative animation

to students:

https://www.youtube.com/watch?v=wGjlT3X

Hb9A

Teacher ask students:

“How do they believe Venus should be shown from Earth according to the

geocentric model?”

Teacher presents the following animation of Venus (geocentric model):

https://www.youtube.com/watch?v=OlnlbZHP-jk

According to the geocentric model can we see all phases of Venus?

Pre-Experiment / Observation– Teaching Phase 1:

Questions Eliciting Activities – DEFINE QUESTIONS FROM

CURRENT KNOWLEDGE

Are there moons on other planets?

According to the geocentric system can

moons orbiting around other planets?

Students are asked to find information about the

predominant cosmological systems in many

ancient civilizations such as ancient Greece

including the noteworthy systems of Aristotle,

Hipparchus and Ptolemy?

Teacher asks students to find

information about the heliocentric

system of Aristarchus and

Copernicus.

What was like the planetary

system of Aristarchus?

Pre-Experiment / Observation– Teaching Phase 2: Active Investigation –

PROPOSE PRELIMINARY EXPLANATION OR HYPOTHESES

December 1610You are now assistant at Galileo's Lab and you receive a letter from

former Galileo’s student Benedetto Castelli:

If the position of Copernicus, that Venus revolves around the sun, is true(as I believe), it is clear that it would necessarily sometimes be seen by ushorned and sometimes not, even though the planet maintains the sameposition relative to the sun. Now I want to know from you if you, with thehelp of your marvelous glasses, have observed such a phenomenon,which will be, beyond doubt, a sure means to convince even the mostobstinate mind. I also suspect a similar thing with Mars near thequadrature with the sun; I don't mean a horned or non-horned shape,but only a semicircular and a more full one.

Pre-Experiment / Observation– Teaching Phase 2: Active Investigation –

PROPOSE PRELIMINARY EXPLANATION OR HYPOTHESES

December 1610Let’ s observe the phases of Venus:

Students are asked to use the Stellarium software and set: Rome

Italy as place and December 1610 as date.

Thus we can see the night sky as been seen from Galileo and of

course his assistant.

Pre-Experiment / Observation– Teaching Phase 2:

Active Investigation – PLAN AND CONDUCT SIMPLE INVESTIGATION

•After setting time, date and

place, students are asked

to locate Venus, according

the following steps:

•Turn off atmosphere,

ground and constellations.

•Search for Venus, using

the search tool (F3).

•Center Venus on the

screen (space bar).

•Zoom in.

•Make time go faster ~ 6 times

•See how the phases change and

try to find out the next new Venus

and full Venus.

•See how the apparent size of

Venus changes.

•Try to relate it to the difference in

magnitudes.

• Venus is brighter in new phase

than in full phase?

• Students are asked to

record the magnitudes of

Venus, in comparison to

time and phases of Venus.

• What can we assume for

the brightness of Venus?

Experiment / Observation– Teaching Phase 3:

Creation – GATHER EVIDENCE FROM OBSERVATION

Time(Day/Month/Year)

Phase of Venus Magnitude

Experiment / Observation– Teaching Phase 4:

Discussion – EXPLANATION BASED ON EVIDENCE

• Students are asked to explain the observed evidences

(experimental data). Do you believe that this observations are

in accordance to the geocentric model?

• Venus forms all phases, or only meniscus?

• How long will take Galileo to observe all Venus phases?

As Galileo’s assistant calculate the period of rotation of Venus,

based on the image above and plot the magnitude of Venus in

accordance to its phases.

Experiment / Observation– Teaching Phase 4:

Discussion – CONSIDER OTHER EXPLANATIONS

Can we further evidence the

heliocentric planetary model?

Galileo observed the moons of

Jupiter. Those tiny light spots

were orbiting around Jupiter

appearing and disappearing in

contrast to the steady stars.

Load Stellarium, search (F3) for

Jupiter.

Center Jupiter on the screen

(space) and zoom in.

Observe the moons of Jupiter.

Make time go faster ~4 times

Go back to 1610 and observe

Jupiter as Galileo did.

Experiment / Observation– Teaching Phase 4:

Discussion – CONSIDER OTHER EXPLANATIONS

Now ask students to use SalsaJ, a free software for astronomical data

processing. By using images taken by telescopes we can animate the

rotation of the moons around Jupiter.

Experiment / Observation– Teaching Phase 4:

Discussion – CONSIDER OTHER EXPLANATIONS

The actions must taken by students are the following:

•Load SalsaJ, a free software available on internet

•From the “File” tab open images downloaded from internet available in

astronomical sites (NASA, ESA etc) preferable format .fts

•Download a time sequence images.

•From “Image” command tab select: “Stacks” and then “Images to Stack”.

•Continuously you can select: “Start animation” and view the video

created by real images, taken by telescopes.

•If necessary apply some “Brightness and Contrast” corrections to the

images by the “Image” -> “Color” commands or by the button.

Post-Experiment / Observation– Teaching Phase 5:

Reflection – COMMUNICATE EXPLANATION

Students can now argue about the

heliocentric planetary model, but

furthermore can explain how this was

proved through observations.

As Galileo’s assistants can present true

observation evidence and support their

believes.

Of course the can respond to Benedetto

Castelli’s letter with the following reply

letter:

O how many consequences and ones of such import have I deduced, my Master Benedetto, from these and from myother observations. You almost made me laugh when you said that with these manifest observations the obstinatecould be convinced. Well then, don't you know that to convince those capable of reason and anxious to know thetruth the other demonstrations already produced were enough, but to convince the obstinate who care only for theempty applause of the stupid and dull crowd, the testimony of the stars themselves, come down to earth to discussthemselves, would not suffice? Let us then endeavour to learn something for ourselves and rest satisfied with thisalone, but as for advancing ourselves in popular opinion or gaining the assent of philosophers in books, let us giveup the desire and the hope.

• As follow up activities, students can observe through Stellarium

the moons of other planet in our solar system.

Post-Experiment / Observation– Teaching Phase 5:

Reflection – FOLLOW UP ACTIVITIES AND MATERIALS

• Furthermore students can search and download their own

images from internet, process them and produce their own

animation with SalsaJ, becoming researchers, after the

experience as Galileo’s assistants.

Contact Information

• Name Surname: Chiotelis Ioannis

• Affiliation: Model Experimental High School of

University of Patras

• Address: Arakinthou 20, 26226, Patras, Greece

• Telephone: +306948372341

• Email: johnchiotelis@yahoo.gr

johnchiotelis@gmail.com

johnchiotelis@icloud.com