Astronomy - Observing Planets in their Orbits

Goal: To observe the positions of an inner and outer planet twice during the month.

Materials and Equipment:

Telescope or binoculars
Star map (either textbook or map from Starry Night)

Procedure:

Plan

Use Stellarium to determine the positions of the planets for your observing sessions. You may need more than one to see the planets that are currently visible: some will only be above the horizon near dawn, others just after at sunset.

The moon is new on 21 September; it will be new again on 21 October 2025 and full on 6 October, so your best viewing will when the moon rises late/sets early around third quarter on October 13. However, you can view from the first six days after new moon (21-25 September) when the moon sets early. The information below assumes you are observing on 13 October 2025, when the moon at third quarter. This is a great month for Saturn in the evening after sunset and for Jupiter and Venus before dawn. Mercury and Mars are lost in solar glare just after sunset. Jupiter becomes an evening planet in December, rising high in the east after sunset. Mercury reaches maximum western elongation around December 12 before dawn. Mercury, Mars, and Saturn will be visible before dawn in early April.

Where will you find Mercury, Venus, Mars, Jupiter, and Saturn in the sky at the beginning of October? Where will each be at the end of the month?
When and where should you look for Mercury?
When and where should you look for Venus?
When and where should you look for Mars?
When and where should you look for Jupiter?
When and where should you look for Saturn?

Observe [You may need to make special arrangements with your parents and/or teacher to observe at the best times or at another time of year.]

Note the date, time, weather conditions, and seeing when you do your actual observations.
Determine when you can see any planets. You may need to observe both in the evening and morning. Plan accordingly!
Can you find Mercury, Venus, Mars, Jupiter, or Saturn with your naked eye? What constellations are they in? What bright star is each one closest to?
Can you observe any features about the light coming from the observable planets that is different from the light of nearby stars?
Now look at the brightest currently visible planets with your telescope or binoculars. If it is visible, try to draw the shape of Venus.
If it is possible to do so, find and observe Mars. What color is it? Can you see any markings on its surface?
If it is visible, find Saturn in a telescope or binoculars. Can you see the ring structure? Can you see a division between the outer and inner rings? [If it is not currently observable, determine when it will be, and schedule an observing session — seeing Saturn and Jupiter with your own eyes is one of the more astounding experiences you can have.]
If it is visible, find Jupiter. Even with an 8X pair of binoculars, you should be able to find 4 small white dots around Jupiter--these are its largest moons, Io, Europa, Callisto, and Ganymede-- very near the circle of Jupiter's surface. Make a drawing that shows the position of the moons. If possible, check Jupiter again on another night. What has happened to the position of the moons?

Report

Your report should include your equipment, the observing conditions, and your actual observations, and some conclusions about the motions of the planets.

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Astronomy