Light Pollution:

A historical study on a modern threat...

Ξανθή Θεοδωσίου, Σεβαστή Μαλάμου, Νικόλαος Μεταξάς, Γεωργία Μιχαλοπούλου

Γιάννης Μίχας, Χρήστος Μουρατίδης, Κωνσταντίνος Νάκος, Μαρία Σουργιαδάκη,

Σεραφείμ Σπανός, Αναστάσιος Τσαμούρης, Ιωάννης Χιωτέλης

Introductory section and preparatory phase

• Short Description: Studying Ancient Astronomers especially in Greece,

Egypt, and Middle East we are astonished by the detailed descriptions of

the Constellations and Stars. Eratosthenes is describing in full detail the

Hydra constellation, while Aratus described the constellations of Orion,

Ursa Minor and Major, Draco and Cepheus. Their ability to observe a wide

number of stars was mainly due to low “light pollution”. Nowadays, stars

are almost out of sight especially in cities due to high levels of “light

pollution”. We will compare the number of stars observed by ancient

astronomers to the number of stars we can observe nowadays, revealing

information about “light pollution” through centuries. We will use hands-on

experimentation, measurements, the Stellarium application and a Google

plug-in to detect light pollution for each place.

• Keywords: Light pollution, Constellations, Stars, Ancient Astronomers.

• Target audience: Students studying Physics and Astronomy.

• Age range: 13-18 years old

• Context: Natural Sciences School Lab, Computer School Lab, Internet

Connection.

• Time required: 6 hours

Introductory section and preparatory phase

• Technical Requirements: Internet connection, appropriate software:

Stellarium, Google Earth plug-in, Microsoft Office, Microsoft Windows,

Computers, video projector could be useful.

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

Constellations, stars. Stellarium, Google+, internet, Google Earth plug-in.

Ancient astronomers descriptions of stars and constellations (use of Wikipedia

can be useful).

• Connection with the curriculum: Strongly related with Astronomy (Second

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

High School). Partly related with Philosophy and ideas of ancient astronomers

and philosophers (Eratosthenes, Hipparchus, Aratos).

• 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 detailed descriptions of stars and constellations developed by

ancient astronomers. Download the plug-in GaN2013.kmz for Google Earth.

Download Stellarium. Both Stellarium and Google Earth GaN2013.kmz are free

in internet.

Pre-Experiment / Observation– Teaching Phase 1:

Questions Eliciting Activities – PROVOKE CURIOSITY

Teacher introduces students in

“Eratosthenica”, book written by

Eratosthenes describing in detail the

constellation of Hydra.

http://www.wilbourhall.org/pdfs/Eratosth

enica.pdf Then asks students to find

how many stars Eratosthenes was able

to observe and describe.

Teacher also presents to students the book of Aratus,

“Phaenomena” referring also to descriptions of

constellations:http://www.theoi.com/Text/AratusPhaenomen

a.html Then he asks question about the detailed reference

to the stars of the constellations.

Finally teacher asks from students to find and collect

descriptions of constellations from astronomers during

centuries, mainly focusing on the number of mentioned

stars (Wikipedia).

Pre-Experiment / Observation– Teaching Phase 1:

Questions Eliciting Activities – DEFINE QUESTIONS FROM

CURRENT KNOWLEDGE

• How many stars can you see from your

house? Match your night sky view with

one of the images beside.

• Visit the site “Globe at Night”

http://www.globeatnight.org/ and find out

the complete scale of “light pollution”.

• Would you see more stars at countryside,

away from city lights?

• Why this happens?

• Which is the main reason for “light

pollution”?

• Search in Wikipedia about light pollution,

reasons, consequences, effects in

Astronomy:

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

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

PROPOSE PRELIMINARY EXPLANATION OR HYPOTHESES

• Students are asked to use the Stellarium software and test

different values of light pollution as shown in figure.

• Also students are asked to count the influence of the

atmosphere to our observations, as shown in the image.

Light pollution

Atmosphere

Pre-Experiment / Observation– Teaching Phase 2:

Active Investigation – PLAN AND CONDUCT SIMPLE INVESTIGATION

• Students then asked to find the

constellation of Hydra and the

description of this constellation by

Eratosthenes. They also asked to

observe the constellation at night by

their own.

• We ask students to record how many

stars they observe from their places and

compare the number of observed stars

to the number of observed stars by

Eratosthenes.

• We then encourage students to find

constellation descriptions of other

ancient astronomers and compare again

their findings.

Pre-Experiment / Observation– Teaching Phase 2:

Active Investigation – PLAN AND CONDUCT SIMPLE INVESTIGATION

• We download the special plug-in for Google-Earth GaN2013

that provides information about light pollution of each place

(yellow dots on the above map).

• Students are encourage to find the original places of primary

observation by ancient astronomers. Then they set at

Stellarium the representative values of light pollution and play

the role of the ancient astronomers.

Experiment / Observation– Teaching Phase 3:

Creation – GATHER EVIDENCE FROM OBSERVATION

• If all those ancient astronomers were observing nowadays the night

sky how many stars would have they seen?

• Students are recording the original places of early observations and

how precise were their observations (how many stars per

constellation):

Year of observation

Name of ancient Astronomer

Number of starsobserved per

constellation by ancient

astronomers

Number of stars

observed per constellation

now

Nowadayslight pollution

at specific place

(by plug-in)

• Then, students are asked to make assumptions about light pollution

at ancient times, and how light pollution is changing our view of sky.

Experiment / Observation– Teaching Phase 3:

Creation – GATHER EVIDENCE FROM OBSERVATION

For greater accuracy we can use a tube

instead of a circle, as shown in the image

above. In this case we avoid hand trembling.

Then students are asked to practice

experimentation and gather

evidence through hands on

activities. By using the experimental

device showed on the side image

can assume the number of stars in

the observation hole, as shown in

the image below.

Experiment / Observation– Teaching Phase 3:

Creation – GATHER EVIDENCE FROM OBSERVATION

http://physcool.web.auth.gr/images/teyxos_5/5%CE%BF%20%CE%A4%CE%95%CE%

A5%CE%A7%CE%9F%CE%A3.pdf

Position Place 1Total number of

stars 1140Average 11,4

Price width 6-16

Position Place 2Total number of

stars 660Average 6,6

Price width 5-8

Position Place 3Total number of

stars 890Average 8,9

Price width 5-13

We are expecting results as in the following TABLE

For even greatest accuracy we ask students to calculate the multiplier factor.

All the stars are not visible, so we must multiply the observed stars by a

multiplier factor.

We ask students to find this factor.

They can refer to the following address for detailed instructions

Experiment / Observation– Teaching Phase 4:

Discussion – EXPLANATION BASED ON EVIDENCE

We ask students to make comparisons with schools from other cities.

To organize an e-twinning network and exchange measurements with

other schools.

We will focus on two or more schools from different regions. An urban

and a rural school, or a school near sea and high on mountains.

These measurements can reveal the differences in light pollution

between different geographical areas.

Experiment / Observation– Teaching Phase 4:

Discussion – EXPLANATION BASED ON EVIDENCE

• Students are asked to confirm or revise their initial ideas about

light pollution. We ask them if they have initially considered how

critical, light pollution is for sky observations.

• Because, many ancient astronomers have observed night sky

from different places (Greece, Egypt, Italy) we ask students to

record locally the values of light pollution:

Place of ancient

observation

Light pollution at ancient

timesLight pollution nowadays

• We ask students to relate light pollution to geographic factors.

For instance: light pollution at developed and developing

countries.

Experiment / Observation– Teaching Phase 4:

Discussion – CONSIDER OTHER EXPLANATIONS

Furthermore we ask students to

observe the traffic lambs during

the night. We encourage then to

combine the light diffusion with

light pollution and how “clear” the

night sky is.

• How can light pollution affect

wildlife in modern cities?

Students are

asked to predict

light pollution and

number of

observed stars just

by looking at the

road lambs.

Post-Experiment / Observation– Teaching Phase 5:

Reflection – COMMUNICATE EXPLANATION

• Students can now explain

why stars are not any

more visible from large

cities.

• Even more students can

combine “light pollution”

with atmospheric pollution

by gases such as CO2. A

polluted atmosphere further

intensifies the problem. The diffused light into the atmosphere

expands the problem far away from the light sources.

• As follow up activities, students can continue recording the light

pollution of the Globe.

Post-Experiment / Observation– Teaching Phase 5:

Reflection – FOLLOW UP ACTIVITIES AND MATERIALS

• We will encourage them to join the

“Globe at Night” project and be a part

of a global research community.

Bibliography• http://www.wilbourhall.org/pdfs/Eratosthenica.pdf

• http://www.theoi.com/Text/AratusPhaenomena.html

• http://www.globeatnight.org/

• http://en.wikipedia.org/wiki/Light_pollution

• http://physcool.web.auth.gr/images/teyxos_5/5%CE%BF%20%CE%

A4%CE%95%CE%A5%CE%A7%CE%9F%CE%A3.pdf

• Spanos S. and Xenakis, C. (2013). Learning Astronomy through

Inquiry and by means of Self-Constructions. Published by Astronomy

and Space Society & Ellinogermaniki Agogi, Athens pp 191.

• Richard G. Stevens , Yong Zhu,Electric light, particularly at night,

disrupts human circadian rhythmicity: is that a problem?

Philosophical Transactions B, The Royal Society. DOI:

10.1098/rstb.2014.0120, 16 March 2015.

• Kevin J. Gaston, Marcel E. Visser and Franz Hölker ‘The biological

impacts of artificial light at night: from molecules to communities’, The

Royal Society , 05 May 2015; volume 370, issue 1667.