Astronomy and Astrophysics – Astronomy
Scientific paper
Aug 2003
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003basbr..23...79m&link_type=abstract
Boletim da Sociedade Astronômica Brasileira (ISSN 0101-3440), vol.23, no.1, p. 79-79
Astronomy and Astrophysics
Astronomy
Scientific paper
Most of people believe that the seasonal change is caused by the varying distance between the Earth and the Sun as the Earth moves on its orbit around the Sun. If the varying solar distance were the cause of change of seasons, both the northern and southern hemispheres of the Earth would have the same seasonal change at the same time. But what happens is that the hemispheres have opposites seasons : when it is summer in the north it is winter in the south; when it is spring in the north it is autumn in the south, and vice-versa. The greatest factor responsible for this occurrence is the 23.5º tilt of Earth's rotational axis relative to the perpendicular to its orbit, and the fact that the Earth's rotational axis maintains a constant direction as the Earth orbits the Sun. This causes a 23.5º tilt of the celestial equator relative to the plane which contains the Sun. Because of this, the Sun can be seen as high as 23.5º above the celestial equator and low as 23.5º below it at any hemisphere. In an attempt to demonstrate why different seasons occur during the time the Earth takes to go around the Sun, a witty and original device was built using low price material such as : sewing machine pulley, wood pulley, woodbasis, wood rod, metal rod, metal bearing, metal axis, leash, nylon wire, double copper wire, isopor ball, pen tube, interrupter, lamp, nipple, plug, crank. This allow teachers to reproduce the device with their students. The idea of building a device with this goal is not new. However, a simple device which keeps the rotational axis of a figurative Earth constant in direction as it moves around the representative Sun was not found out in astronomy teaching literature. This device allows this to occur because the pen tube (which acts as the Earth's rotational axis) remains free to spin around the metal axis, kept settled. The pen tube is connected by a leash to the metal rod settled on the wood basis. When the wood system rod + pulley is turned round through a crank, the representative Earth's rotational axis (pen tube), is kept free to spin around the metal axis, maintaining its initial configuration. It is worthwhile to notice that the metal rod and the pen tube must have the same thickness. That is necessary because after a full revolution the wood system rod + pulley and the pen tube must return to the same position to keep the representative Earth's rotational axis with its initial configuration. The teacher may also explain to the students that the Earth's rotational axis really changes its positions in a very smooth way, in a period of nearly 26,000 years. This time is much greater than the lifetime of a human being, but this motion is noticed since ancient time. The device works as a helpful instrument to a teacher in any introductory astronomy course.
Couto da Silva T. C.
Marques J. B.
Rocha P. S.
No associations
LandOfFree
Seasonal change: a device built to show why and how it happens does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Seasonal change: a device built to show why and how it happens, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Seasonal change: a device built to show why and how it happens will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1665437