Chabot College

Scott Hildreth

Astronomy Worksheet

Star & Planet Locator Explorations: Locating Planets

"There is a geometry in the humming of strings. There is music in the spacings of the spheres." -- Pythagoras, 6th cen. B.C.E.

Set your star locator so that today's date on the moveable wheel is opposite 8 PM on the clock. (Be certain that it is 8 PM, and not 8 AM! Look for 6 p.m. and 11 p.m. nearby.)

a) Why aren't the planets visible on the front of the star wheel? Are the planets always in front of the same stars? Are they visible in the same locations every year? Let's find out.

star and planet locator ecliptic line

On the front of the star wheel, locate the ecliptic, which is the path our Sun appears to take around the sky during a year, and also the part of the sky where the planets will be seen. (Why?) Identify the zodiac constellations along the ecliptic that you can see this night at 8 PM. Start with the constellation nearest the eastern horizon:



Zodiac Constellations visible tonight at 8 pm:

 in the eastern sky:

 near the meridian:

 in the western sky:

b) On the back of the Edmund's locator is a shaded table of Planet Places. Look in the table for the current year and month, and complete the chart below for the 5 planets we can see by eye in our sky (without a telescope). Note that the number in the chart refers to the constellation that planet will appear near during the month and year. Be sure to read the explanation on the locator about what the () and underline mean regarding the planet's apparent location in the sky!


 Planet  Const. #s  Constellation Name(s)  Evening Sky? Morning Sky?

c) Now from your chart, turn the locator over and locate on the star field the zodiac constellations you can see at 8 pm that will contain planets. In the sketch below:
1) draw in the ecliptic,
2) label the zodiac constellations in their approximate locations along the ecliptic, and
3) position the planets you can see within those constellations.

star and planet loctaor sky area
d) Examine the Planet Places table on the back once more. In one month, which planets will have moved? Which will still be in front of the same zodiac constellation?

These planet(s) will have moved in 1 month:
These planet(s) will still be in the same area:

e) What about in 1 year? Look at the table for the same month, but for a different year (either last year, or a year from now.) Which planets were in seen in the same zodiac constellations as they are in now? Were any?

Develop a hypothesis to explain your result. Consider how fast the planets orbit our Sun, and whether they all must be orbiting at the same speed or different speeds. Use that hypothesis to explain why Edmund does not put the planets on the front oval star field.





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