ASTR 110L
Spring 2008
Sectio
n 1
Observing Lunar Features
Sketching the Moon
Sketch tonight’s Moon, and include the following:
a. (1 pt.) The terminator
b. (3 pts.) The outlines of major maria that are visible tonight
c. (1 pt.)
Major rayed craters that are visible tonight (most
important: Tycho & Copernicus, plus any others)
d. (1 pt.)
Other prominent craters (include central peaks, if any),
mountain ranges, or other features
e. (1 pt.) Date, time, telescope/eyepiece/filter, and location
Tips
• Use unlined paper. It is easiest to start with a circular outline
(like the one provided to you in class).
• Use pencil.
Sketch with lines (either light or heavy, for sharp
boundaries of features) and shading (for shades of gray or shadow).
Decide whether you want shading to represent light or dark — I
recommend pencil for dark, and blank white paper for light. (Make a
note on the side of the sketch if you choose the opposite of this.)
• First, draw the terminator on your sketch.
This provides a very
useful reference for further sketching.
Craters and mountains stand
out best along the terminator, which is the line between day and night
on the lunar surface, while craters in broad daylight tend to wash out
and are harder to see. (Thought question: why?)
• Features on the dark side (night side) of the Moon will be visible
only if the phase is a very slim crescent; usually, no features are
visible, and you don’t need to worry about sketching anything there.
Just shade it in.
• Second, draw the outlines of the major maria.
If they are dark,
shade them a bit. They should look noticeably different (both in real
life and on your sketch) from the surrounding highlands.
• Third, sketch the major rayed craters, making sure to show the
direction and extent of their rays. (Even though the rays are usually
light, you can use your dark pencil. Make an explanatory note if you
wish.)
• Finally, you can draw a few of the other largest (unrayed) craters,
perhaps those with prominent central peaks; any obvious mountain
ranges; or other features.
It’s impossible to draw every crater.
Start with the general outlines of the largest features and most
salient/obvious features (like rayed craters), then work your way down
to smaller ones if time permits.
• Always label your sketch with date, time, telescope/eyepiece/filter
used, and location.
f. (1 pt.) Later, label the direction of North on your sketch
g. (2 pts.) Later, use a Moon atlas/map to label the following
features (not all are necessarily visible, depending on the phase of
the Moon):
Mare Crisium
Mare
Mare Nectaris
Mare Fecunditatis
Tranquillitatis
Mare Serenitatis
Mare Imbrium
Mare Nubium
Mare Humorum
Oceanus Procellarum
questions on back…
Tycho
Crater
(rayed)
Copernicus
Crater
(rayed)
Optional:
Any
other
major
craters or mountain
ranges
on
your
sketch that you can
identify using maps
Homework Questions
At home, answer the following questions (on a separate sheet of
paper):
1. How do the lunar maria and highlands look different to the
naked eye, or with a telescope? Specifically:
a. (2 pts.) Which has the higher or lower albedo? Why?
b. (2 pts.) Which is more or less heavily cratered? Why?
2. (3 pts.)
Look at Mare Crisium (“Sea of Crisis”) with the
telescope.
What do you think happened to create Mare Crisium,
and what about its appearance supports this?
Is the floor of
the mare heavily cratered or mostly smooth? Do you suspect that
the little craters on the floor of Mare Crisium occurred fairly
recently, or very early in the life of the Moon?
3. (3 pts.)
Look at Mare Serenitatis (“Sea of Serenity”) with
the telescope.
Can you see the ray crossing the mare?
(It’s
visible on the Moon map, too.) Which major rayed crater on the
Moon does it look like that ray originated from?
Physically
speaking, what are crater rays? Which craters should we expect
to see rays around: very recent or very old craters, and why?
4. (2 pts.) The lunar surface is covered by a few-inches to a
few-meters-thick covering of regolith.
What is it, and how do
you think it forms?
(Remember that the Moon has no air,
atmosphere, or wind.)
5. (2 pts.) Why doesn’t the Earth have many impact craters on
its surface… or does it? (There are several reasons — give as
many as you can think of.) Relatedly, why doesn’t Earth have a
layer of regolith… or does it?
Bonus (? pts.):
Discuss anything else interesting.
on your Moon diagram, and try to identify it later.
Sketch it
MOON
Date & time:
Telescope/Filter used:
Use the above circle to represent the edge of the Moon, NOT the edge of your
telescope’s field-of-view.