Lab          B0        PLANETS

 Objective: Observe as many planets as possible.

 Observe the planets on your own. You don't need a telescope for that.  You find the positions of the planets in the sky on the back of your starfinder.  Check also my lecture The Monthly Sky and the Observing pages at Sky & Telescope magazine .

1. Which planets are very bright?
2. Which planet is just on the brink of naked eye visibility?
3. Which two planets can be only seen through a telescope or on photos?
4. When looking at stars and planets, how do you perceive them? What are differences? What do they have in common?
5. Write down what you saw for each planet.  This can be naked eye observations, so e.g. you might just say "very bright" for Jupiter, or "can't see" for Pluto.
6. In which constellations can you see the planets (check your starfinder)?  In that respect what do the planets have in common with the Sun and our Moon?

 

 Venus

 Mars

 Jupiter

 Saturn

 Uranus

 Neptune

 Pluto
 
 
 

Objective: that once and for all, all my students understand why our Moon has phases.

This lab is due five weeks after it is assigned (weather permitting).  Students are required to do this lab!

Procedure:  Starting a day or two after the new moon, observe the moon every day for one month, make a drawing of its shape, write down when (date and time of day/night) and where (E-S-W, high, low) you saw it.

Hints: Weather permitting, observe our Moon just after sunset for 2 weeks until full moon - that way you notice how the phase changes as our Moon progresses West-East in a day-to-day motion..  If it seems to get cloudy after sunset, you have to choose another time, though - maybe even in the late afternoon.
After the full Moon you need to wait an hour more every day for the moonrise.  Eventually (1 week or earlier after full moon) it rises too late, so switch to morning observations - any time before 10 a.m. will work.

1. How does our Moon change phases from day to day?
2. Why do we think of our Moon as a night object?
3. Explain, why we can see our Moon during daylight.

PS "Our Moon" means Earth's Moon.  We will use "the" or "a" moon when we refer to the moons of Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, and the asteroid Ida’s moon Dactyl.
 
 

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Objective: That once and for all, all my students understand the correct reasons for the seasons.

This lab is due at the end of the semester.  Students are required to do this lab!

Description: One of the greatest misunderstandings we have about science is why the Earth experiences seasons.  In class you will learn early in the semester that it's the tilt of Earth's axis as we orbit our Sun.  This explanation will make sense to you when we do the modeling in class.  For true understanding, however, you need to observe our Sun’s motions and draw your own conclusions.
PS We will call "our" Sun that way because it is "our" star, as compared to the other stars, each of which is "a" Sun for its planets (if it has planets).

Warning: Do not look at our Sun through a camera, binoculars or telescope - as it can cause damage to the eye!  Avoid also looking directly at our Sun as it can blind you temporarily.  We will do this in class with special solar filters (but online students don't do that).

Procedure:

1. Make three drawings: each drawing has a horizon line and extends from NE through E, SE, S, SW, W to NW.  Put S in the middle, NE on the very left, NW on the very right.

2. Early in the semester, you pick a day where you get up early to (a) observe Sunrise (write down time and direction: NE, E, or SE), then (b) at noon determine direction (most likely South, right?) and altitude (estimate in degrees) of Sun (at 1 am during daylight savings time), then (c) Sunset (again time and direction).  (d) Size:  Hold your thumb at arm’s length and see if it covers our Sun.
2a. Direction: (i). Streets (or avenues) in Gering and Scottsbluff run East-West (or North-South), most houses are built so their walls face the four directions.  (ii). Use a compass.  (iii). Observe Polaris and remember where exact North is.
2b. Altitude (in degrees) of Sun:  (i). Estimate our Sun’s altitude.  Use method this method!  (ii). You need a stick and a ruler (or tape measure).  Measure length of stick.  At noon set the stick vertically (!) above the ground.  Measure the length of its shadow.  Divide length of stick by length of shadow.  Take the inverse tangent (tan^-1) of this number (make sure that your calculator is in DEC mode, not in RAD - of course, you can ask the instructor on how to do that).  Compare the result to your initial estimate.  (iii). There is a third method, but since I don’t want you to look at our Sun, I advise you to avoid this method.  By using a protractor and a plumb line you can determine the altitude as well.  However, the stick and shadow method is more accurate because you can hardly do anything wrong.

3. Draw your observations into your first diagram.  Connect our Sun’s positions with a nice, smooth arc.

4. Every week pick one day and write down sunrise and sunset (in the newspaper or your own observations).  (Keep a log.)

5. Repeat this procedure on or around the equinox (March 21, Sept. 21; solstice June 21, if summer semester) and towards the end of the semester.
 

Questions:
1. Does our Sun arc through the South or the North?  Why one or the other?
2. Does our Sun rise / set always exactly in the East / West?  Why or why not?
3. Would you think that the amount of time that our Sun is above the horizon can be linked to the amount of heat we get during a day?  Explain.

Questions not related to seasons:
4. How can our Moon be out during daylight?
5. Note that during twilight more and more stars appear as the sky gets darker.  What do you conclude about the stars being there (or not being there) during daylight?
6. The sky is black during night because there isn’t a bright enough light source like our Sun.  Does the blue sky during daylight have anything to do with our Sun?  Explain.

Explain YOUR theory of seasons.  Your theory MUST explain your observations - you just can’t make up rules that contradict the observations.

Objective:  Observe the variable star Mira.

1. Find information about Mira.

2. What is the mechanism that makes Mira vary in brightness?

3. Finding Mira (o Ceti): it’s West of Cetus’ small pentagon and until about 2000 fairly close (below) Saturn or Jupiter.

4. Observe Mira every month.

5. Compare its brightness to surrounding stars.

6. Make a log of your observations.