TRANSIT OF VENUS: SCHOOL ACTIVITIES
by Knut Jørgen Røed Ødegaard
How do we measure the distances in space? Several hundred years ago,
the transits of Venus were used to determine the dimensions of our
Solar system. Here you can find out how this was done and how you can
do this yourself!
Below we present two practical exercises aimed at schools and others
with an interest in this subject. The first exercise is to measure the
size of the Earth and this you can do at any time. The second one
can only be done on the 8th of June: it involves measuring the
distances in space!
The two problems provide an insight into the unique effort that made
it possible to determine the scale of our Solar system. In the
following presentation, little knowledge of mathematics is assumed.
For those specially interested, there are links below to a range of
Through these exercises the student will - in a new and unique way -
learn about space and the sizes and distances to our neighboring
celestial objects. We hope that everyone takes advantage of this
To carry out the calculations you need to compare your measurements
with those obtained at a different location on the Earth. Thus it is
important to register as soon as possible. See the link "Registration"
in the exercise sections below.
|Exercise 1: HOW TO MEASURE
THE CIRCUMFERENCE OF THE EARTH|
AND HOW TO MEASURE
You can easily make the equipment you need yourself. A long straight
tube and a spirit level are the most important things. Collaborate with a
school far away and measure the size of our planet! The method was
used for the first time in Egypt almost 2500 years ago.
THE SIZE OF THE EARTH
You have now measured the altitude
(elevation above the horizon) of the Sun (link above). Before you
continue, you or your teacher must exchange results with the
REGISTRATION: IMPORTANT INFORMATION FOR TEACHERS |
In order to estimate the size of the Earth you need to exchange
results with the school you are collaborating with.
MORE INFORMATION / BACKGROUND MATERIAL:|
THE EARTH WAS MEASURED
Almost 2500 years ago an Egyptian managed to calculate the
circumference of the Earth! It was a major achievement. Here you can
find out how he did it.
Exercise 2: HOW TO MEASURE THE DISTANCE TO THE SUN|
1: TIMING THE CONTACTS BETWEEN VENUS AND THE SOLAR DISK
This method is based on the fact that the
entrance and exit times will be slightly different when observed from
different parts of the world. One can use this principle to find the
distance from the Earth to the Sun.
METHOD 2: MEASURING THE PATH OF VENUS ACROSS THE SOLAR
This method is based on the fact that Venus will move
along two slightly different paths across the solar disk if the
transit is observed from two different locations on Earth. One can
utilize this to find the distance from the Earth to the Sun.
Once you have made the observations you are invited to register the
this registration form.
INTERNATIONAL SCHOOL CAMPAIGN|
Since a transit of Venus is a truly historic event, an
international school campaign has been organized. Students - and
others - from the whole world are encouraged to participate and make
as accurate measurements as possible.
Main page for the Transit of Venus event
|MORE INFORMATION / BACKGROUND MATERIAL:|
AND THE DISTANCE TO THE SUN
What is parallax, how is it measured and how can we use it to determine the
distance to the Sun?
DETERMINATION OF THE SUN-EARTH DISTANCE USING THE PATH OF VENUS
ACROSS THE SOLAR DISK (METHOD 2)
A transit of Venus offers a unique possibility for us to measure the
actual distance to the Sun. Once this quantity is determined, we can easily
compute the other distances in the Solar system by using Kepler laws.
THE POSITIONS OF THE PLANETS RELATIVE TO THE EARTH AND THE SUN
The inner planets of the Solar system, Mercury and Venus, can never be
very far away from the Sun in the sky. Here you will find the reason why,
and you will also understand other concepts related to planetary orbits and
why Venus only covers a small fraction of the Sun during a transit.
THE EARTH'S AND VENUS' RELATIVE DISTANCE TO THE SUN
With the transit of Venus in 1769, astronomers for the
first time managed to determine a rather accurate distance to the
Sun. However, the relative distances between several objects in
the Solar System were already known. In 1543 Nicholas Copernicus
published a work describing the workings of the Solar system. It also gave a
determination of the relative distances between the Earth and the Sun
and between Venus and the Sun.
KEPLER'S LAWS DESCRIBE THE MOTION OF THE PLANETS
For hundreds of years astronomers studied
the movements of the planets with increasing accuracy. But it was hard
to describe their orbits mathematically. We only see the planets
projected onto the sky, so we can only study their apparent motion
against the stars. It is not trivial to observe how the planets really move
around in space - towards us or away from us.
How to become an astronomer (in Norwegian)
CONTACT INFORMATION - PRESS CONTACT
Created 05 June 2004 by Jan-Erik Ovaldsen