Category: Mars

 

This series of sketches covers my observations of Mars around the opposition
of 2003. Various telescopes were used including a 105mm Astro-Physics apo, a
200mm TEC Fluorite apo, a 13-inch Merz Refractor (circa. 1859, Herstmonceux,
Sussex, England) and a 28-inch Grubb Photo-visual Refractor (circa. 1893,
Royal Observatory, Greenwich, England). Simple graphite sketches with colour
notes were carried out at the eyepiece, generally over a 30 minute to one
hour period, these coloured pencil sketches then being drawn as soon as
possible afterwards. Interestingly the same sort of view is distilled out of
each observation regardless of the aperture being used!

Though the view didn’t appear to change very much from one evening to
another, the shrinking southern polar cap and changing phase of Mars is
distinctly seen over the three month observing period. My personal challenge
for the current Mars apparition is to catch the gibbous phase BEFORE
December 2007 opposition as well as afterwards.

The disc diameter of the sketches (image flipped to the correct orientation)
is approx. 5cm, and south is up.

Sally Russell

With Mars rising in the early morning hours and slowly increasing in apparent
diameter, Mars observers are already gearing up for this apparition, even though
opposition and closest approach are still six months away.

Along with the opportunity to see the bright Martian South Polar Cap, the North
Polar Hood (the clouds surrounding and hiding the North Polar Cap), famous albedo
features like Syrtis Major, atmospheric clouds, and the giant shield volcano Olympus
Mons (the mightiest volcano in the solar system), observers always have the
potential to see a dust storm develop on Mars.

Although dust storms on Mars can become giant planet-encircling storms that obscure
the surface and cut short the observing season (as happened in 2001), they can also
remain regional, expanding rapidly to cover an area the size of the continental US
and then subsiding.  At least two regional events occurred during the 2005
apparition.

The excellent set  of Mars sketches by Jeremy Perez on ASOD (8 May 2007) prompted me
to look through my own logbook where I found these two observations made three days
before Jeremy’s drawings.  This storm had first been recorded by imagers on 18
October in the area known as Chryse, site of the first Viking landing.  By the time
of my first observation, the dust had spread south and was already obscuring
familiar dark albedo features.

In the second observation, Mars had rotated about 40 degrees of longitude, but the
dust had been travelling rapidly west, apparently flowing through the immense fault
(4500km/2800miles) known as Valles Marineris which is associated with the albedo
feature Coprates.  The dust later spread over Solis Lacus (the Eye of Mars) and on
towards the south polar region but never turned into a global storm.

This dust storm was bright in unfiltered light but observers wishing to track dust
closely need to use red filters–dust is bright in red light.  Wratten #23A and #21
filters are good for small apertures of 8″ (20cm) or less.  Those with larger
instruments can use the W25 filter.

The sketches were done using 2B, HB, and 4H graphite pencils, color pencils, and a
blending stump on Strathmore 70 lb. paper.  The circle templates are 2 inches.  I
like to include the line drawing diagram next to my sketch to label important
features without making the drawing too busy.

A dust storm developing on Mars is a fascinating natural phenomenon to see.  Good
luck with this apparition and Happy Mars Observing!

Michael Rosolina
Friars Hill, WV  USA