You can also scan a color film image, even one
you took many years ago. As you process the picture, look out for “crossover” — color casts that are
different in brighter than in darker areas. Crossover
was the main bugaboo of color film and one reason
that digital photography displaced it so quickly.
Do the Magic
Bring the image into Photoshop or another image-processing application, then simply increase the
color saturation. In Photoshop, this adjustment
is accessed via Ctrl-U on a PC and Command-U
on a Mac.
Look at the results as you turn up the saturation.
Don’t go too far — if the image becomes grainy
or gaudy, you’ve gone beyond the colors actually
recorded from nature and are now looking at camera artifacts. It may work best to make the adjustment in 2 or 3 steps.
Finally, you may want to do some sharpening or
unsharp masking to bring out lunar details. After
processing, you can save your picture as a JPEG
because the low-level colors are no longer hidden.
What You’ll See
There are three basic kinds of moon rocks: highland material (feldspar), low-titanium basalt, and
high-titanium basalt. These come out as pinkish,
grayish-yellow, and blue, respectively. (The powder,
or regolith, on the lunar surface is mostly similar to
the rocks beneath, although it also contains material from micrometeorites.)
Note especially the blue color of the Mare
Tranquillitatis (aka Sea of Tranquility), contrasting
with the other lowlands. Apollo 11 landed in an
especially blue patch here because it is flat terrain
with few boulders to run into.
Greenish tints can indicate places with higher
iron concentration, although the edge of the sunlit
region can also appear green because that’s how
the rocks look when lit from the side.
Photograph by Simon Quellen Field
Other unusual tints have been reported in Sinus
Iridium (aka Bay of Rainbows) and around the
crater Aristarchus, which has a reputation for odd
behavior — it reflects sunlight so brightly that it’s
been mistaken for an erupting volcano.
By day, Michael A. Covington is a senior research
scientist at the University of Georgia. By night, he
photographs the sky and writes books about it, such as
Digital SLR Astrophotography (
DIY Ion Engine
BY KEITH HAMMOND
To get to Mars, we’ll use the same
technology as Darth Vader’s TIE fighter
— the ion propulsion engine. It uses
electricity to produce a plasma of
charged ions exiting 10 times faster than
chemical rocket exhaust.
The most powerful ion engine today is
Ad Astra Rocket Company’s 200-kilowatt
VASIMR plasma engine, which uses radio
frequencies to superheat argon ions to
1,000,000°F. Ad Astra’s founder, former
NASA astronaut Dr. Franklin Chang Diaz,
estimates a nine-month one-way trip
to Mars could be cut to 39 days using
200-megawatt plasma engines.
Until then, Simon Quellen Field shows
how to make your own tiny ion motor
using just a high voltage source and two
paper clips, at his website Science Toys
You Can Make With Your Kids (makezine.
com/go/ionmotor). The journey of 100
million miles begins with a single ion.
TINY ION: Replicate
the basics of an ion
propulsion engine using
a piece of wire, the cap
from a D battery, and
a power source.