Moon Mapping
Measure the luminosity of the total lunar eclipse like an astronomer!
Collect
• Notebook or sketch pad
• Colored pencils
• Danjon Scale card
• Binoculars or telescope, optional
Observe the Eclipse!
1. It is best to determine the brightness of a lunar eclipse around the time of mid-totality. The mid-totality is
the middle point of the eclipse when the Moon is fully covered by the umbral shadow of the Earth. The
umbral shadow is the innermost and darkest part of a shadow which completely blocks a light source, in
this case, the Sun. In Baltimore, mid-totality will occur around 3:30am on April 15th.
2. Make a drawing of the eclipse. Make sure to record the time of your drawing and note whether you are
using binoculars, a telescope, or viewing with your naked eye. Take notes on the variations in color and
brightness, as well as the sharpness of the shadow’s edge and the visibility of lunar features.
3. Determine the luminosity of the eclipse using the Danjon Luminosity Scale. Tweet us your drawings
@MDScienceCenter #TotalLunarEclipse
How it works
Even though the Earth is completely blocking the Sun during a total lunar eclipse, we see light and color on
the Moon because of the Earth’s atmosphere. As light passes through the atmosphere, not all of it is
absorbed; some of it becomes bent or refracted. Some of this refracted light is then able to reach the moon.
The color and brightness of a total lunar eclipse also depends on how much dust and clouds are present in
the Earth’s atmosphere during the eclipse.
Cool Science
Check out your own umbral shadow! Go into a dark room at home. Stand between a lamp and a light-colored wall. Turn on the lamp and check out your shadow on the wall. Does your shadow have the same level
of darkness on the edges as it does in the middle? Your umbral shadow is the innermost part of the shadow
where the lamplight can’t reach the wall.
601 Light Street Baltimore, MD 21230 • www.marylandsciencecenter.org
The Danjon Scale is a visual observation tool used to measure the appearance and luminosity, or brightness,
of the Moon during a total lunar eclipse.
Danjon Luminosity Scale
L=0
Very dark or almost invisible, especially at
mid-totality.
L=1
Dark gray or brownish in coloration, details and
features are distinguishable only with difficulty.
L=2
Dark red or rust-colored central shadow, with a
relatively brighter outer edge.
L=3
Brick-red central shadow usually with a brighter
or yellow-tinted rim.
L=4
Very bright copper-red or orange central
shadow with a bluish, very bright rim.
601 Light Street Baltimore, MD 21230 • www.marylandsciencecenter.org