Tonight you will determine the location of Venus in its orbit around the Sun and the distance between the Earth and Venus.
Your first task is to go outside, face the western horizon, and make a sketch. Your sketch should include the following features, all drawn in their proper places:
Use your sketch to estimate the angular distance between Venus and the Sun. You may use the rough rule that a fist held at arm's length subtends about 10 degrees, or you may devise some other means to measure angular distance. Describe the method you use, and state clearly your estimate of the angular distance in degrees.
Each person in the class must make a sketch of Venus. Groups should discuss their sketches and come to a consensus.
Your next job requires a telescope. You must use the same telescope and same eyepiece to make the observation. Your goal is to draw the shape of Venus: is it a disk, a crescent, or something in between?
Point the telescope at Venus and focus carefully. Draw a picture of Venus, using the circular frame of the picture to denote the edges of the field of view. Try very carefully to depict the shape of the visible portion of the planet.
Use the SkyMap Pro program to check the the actual distance from the Earth to Venus. How close was your value? Can you explain which step in your observations and calculations is responsible for most of any error?
This page maintained by Michael Richmond. Last modified Apr 10, 2002.
Copyright © Michael Richmond. This work is licensed under a Creative Commons License.