29:51 Introductory Astronomy Lab

Spring 2001

Experiment 3

Week of February 12, 2001

Observations of the Planets Venus, Jupiter, and Saturn

This week we will (hopefully) take advantage of the spectacular assembly of the planets to observe Venus, Jupiter, and Saturn. The session will take place on the roof of Van Allen Hall. Meet in my office and we will set up the Celestron 8 on the pier on the roof.

Important aspects of the planetary system will be revealed by repeating these observations on a different night. Next week would be a good spacing, and it would be ideal to observe Venus once a week for the next six weeks.

Be sure to make careful, scientific-diagram-quality drawing of the objects.

Venus: Note the size and shape of disk of the planet as it appears to you. Recall what the shape was in the session when we observed at my house. Particularly note the size, and try to compare it to Jupiter, which we will observe next. The best approach would be to observe Venus, turn to Jupiter, then return to Venus. Carefully note the size, and draw the planets to scale, as best you can.

Jupiter: If it is clear Wednesday night, we will go for it. However, the optimum situation would be to have clear skies Thursday night. The reason for this is that the famous Great Red Spot will be on the “central meridian” (i.e smack-dab in the middle of the disk, in the lingua vulgaris) at 6:40 PM Thursday night. It would be a great thrill to be able to see it.

You should also carefully note the spacing and arrangement of the moons of Jupiter, and see if they agree with the map reproduced here. During the two hour duration of the session you should see some subtle, but perceptible changes in the positions of the moons.

Carefully record the appearance of the Great Red Spot (or, alternatively, say that you cannot see it).

Saturn: Sketch the appearance of the planet, and look for structure in the ring (Cassini’s Division). Look in the vicinity of the planet for the moon Titan. Its position should be recorded for comparison with later observations.

Be sure to use this opportunity to make measurements of the celestial positions of the planets, while they are in the vicinity of the bright stars of Taurus, Orion, and Auriga.