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Go Observe – The Terminator

By Deirdre Kelleghan  |  4 May 2018

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Waxing crescent moon with a well-defined terminator and a little Earthshine. Pastel sketch February 11th, 2008 200mm dob. Deirdre Kelleghan Waxing crescent moon with a well-defined terminator and a little Earthshine. Pastel sketch February 11th, 2008 200mm dob, 4.83 days. Deirdre Kelleghan

When the phrase “The Terminator”  is mentioned in may conjour up  ominous dark tones lurking within its meaning.  A science fiction phrase where a cybernetic organism  can ask for  ‘your clothes, your boots, and your motorcycle’ then ride off to alter the course of humanity.  Or the visually rich line that demarks daytime on the moon’s surface from night-time on the moon’s surface.

The terminator is far from a straight line, it is ragged and uniquely fluid. Sunlight illuminates unevenly as it fills craters.  Shadows form and transform during its progression across the lunar topography. Craters that penetrate the terminator and show their rims as glints of light in the blackness bring a tactile quality to a sketch.  Lunar sketching in the area of the terminator often brings up a dilemma . When a sketch takes several hours, sometimes the terminator vista alters to offer a new and brightly lit feature.  This crater or mountain only revealed as you finish. Do you put it in or not ? In general if it adds to the sketch yes, if it is a mediocre addition no.

Recently I came across the  moon drawing above in one of my portfolios . The sketch includes a very well-defined terminator and a touch of earthshine.   The drawing  was devoid of information , no day, date or time was written on the sheet.  A bit of a hunt provided the basics, but not all information was available and my memory yielded very little. Sometimes I might publish a sketch in a forum or group. All the information relating to the drawing can be online but not necessarily on the actual drawing. Note to self and others, always write the sketch details on the work.

Along the terminator visual richness pulsates with abundance. Take a terminator tour with your telescope , it doesn’t matter if it’s a small or large instrument. It doesn’t matter if you do not know the features that you are seeing.  Just enjoy the moon for itself, identity of features can come later. Contrast is sublime, blacks are pure, whites are sharp and exciting. Watch sunlight gain lunar ground on a waxing moon.  Feast your eyes as mountains reveal themselves in complex craters. Shadows will alter before your eyes, giving or taking away from the appearance of craters.

Sometimes even a 98% moon terminator can bring joy and results. A previous blog about drawing along the terminator tells that story from Dunsink Observatory Dublin.   Eddington Crater on the Moon  

Lunar Software

Virtual Moon Atlas 

Google Moon

Inconstant Moon

 

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