Press Release

Launch of Human Orrey at Armagh Observatory

By SpaceRef Editor
November 26, 2004
Filed under , ,

The Armagh Observatory’s “Human Orrery” is the first large outdoor exhibit
in the world to show accurately the elliptical orbits and changing relative
positions of the planets and other solar system bodies with time. It has been
constructed with the support of the Northern Ireland Department of Culture,
Arts and Leisure (DCAL) and is the first major addition to the Observatory
Grounds and Astropark for more than a decade. A ceremony to mark its
construction will take place at the Observatory on the morning of Friday 26
th November.

An orrery is a dynamic model of the solar system, designed to show the
positions, relative orbits and distances of the planets about the Sun. It shows
the orbital periods of objects revolving around the Sun and can be used to
illustrate a wide range of celestial phenomena, including planetary alignments,
conjunctions, transits, and the laws of orbital mechanics.

The name “Orrery” for the first orrery, which was invented 300 years ago by
the English clockmaker and inventor George Graham (c.1674-1751), was
popularized by the Irish essayist Sir Richard Steele (1672-1729), in honour of
Charles Boyle (1674-1731), the fourth Earl of Orrery. The name has since been
attached to any device designed to show the planetary motions.
In the Human Orrery, people play the role of the moving planets and other
solar system bodies. The model provides an accurate map of the orbits of the
six naked-eye planets, an asteroid and two comets, and shows their positions at
any time. When the exhibit is finally completed, it will also show the
thirteen zodiacal constellations through which the Sun passes in the course
of a year and the directions to a wide range of more distant objects in the
Universe. Mark Bailey, the Observatory Director, said: “The Human Orrery is
a great way to explain the Earth’s position in space. You can look at the
positions of the Sun, planets and other objects on the ground and immediately
work out which objects are visible tonight, or at any other time, and where
they will appear in the sky relative to one another.”

The Human Orrery is also great fun to use. It provides a wealth of
fascinating educational opportunities to engage people not just in science and
mathematics, but also in the art of learning how to observe and take careful
measurements, and so how to discover new things about the world in which we

The “inspiration” of astronomy extends well beyond pure and applied science
and technology, and the launch of the Human Orrery is therefore also an
opportunity to highlight the breadth of cultural activities supported by the
DCAL as well as astronomical research. In particular, the Launch will include
the performance of an innovative “Dance of the Planets” performed by children
from the local Armstrong Primary School.

The Opening Ceremony will begin at 11:45 in the Observatory library, and
will include formal contributions on behalf of the Observatory, the DCAL and=
the Particle Physics and Astronomy Research Council (PPARC). Many of those who
have contributed to the creation of this world “first” for Armagh will be
present, as too will other invited guests and some of the Observatory’s
staff, students and senior management.


Professor Mark Bailey or Dr. Apostolos Christou

Armagh Observatory

College Hill


Northern Ireland BT61 9DG

Tel: +44 (0)28-3752-2928

Fax: +44 (0)28-3752-7174

E-mail: (mailto:[email protected]) or
(mailto:[email protected])

Web site: (
Further information about the Human Orrery is available from the Armagh

Observatory web-page,

( , which shows images of the Human Orrery
under construction and links to the first two Human Orrery leaflets,
funded by the PPARC, which have
so far been produced in support of the exhibit.

SpaceRef staff editor.