Youth and Beauty

By Frank McCabe   The grip of winter is loosening just a little with breaks in the nearly constant
cloud cover and temperatures occasionally going above the freezing point. I am
looking forward to nights of observing that don’t involve shivering. This night
although below freezing was wind free and temperature tolerable. The promise of
spring is nearly here.

  Tycho crater in the southern highlands was the target of my sketch this evening.
At 85 kilometers in diameter this large, young, complex crater exhibits fantastic
terraced walls and slopes with a large flat floor partly strewn with melt debris.
A pair of central peaks casting shadows to the southwest could clearly be seen. A
distance of 4.8 kilometers separates the floor from the crater rim and the central
peak stands tall at 2.4 kilometers. Wall slumping down to the west floor puts it a
little higher than the eastern floor. Rays extend outward from Tycho in most
directions. Some of these bright rays reach out 2000 kilometers across the lunar
surface. Tycho at 108 million years old is the youngest large crater visible on
the earth facing side of the moon. In the 1960’s this crater was briefly
considered as a landing target for an Apollo moon mission. Surveyor 7 spacecraft
soft landed successfully north of the crater in January of 1968. Ray distribution
from Tycho which is best seen at or near full moon, illustrates that the impactor
of mountain size came in at a shallow angle to the surface from the west and
ejected lunar highland crust and blocks mostly in non-western directions.

  Land vertebrate life on earth was thriving quite nicely at this time since this
was 43 million years before the Chicxulub cratering event here on earth which
ended the good times for the “terrible lizards”.

  Apollo 17 astronauts collected among the rocks and soil returned to earth samples
of the Tycho ray debris at the Taurus-Littrow valley including calcium rich
anorthosites that aided in dating the Tycho crater event.
  
  
  Sketching:

For this sketch I used: black Strathmore 400 Artagain paper, 8”x 11”, white and
black Conte’pastel pencils and a blending stump. Brightness was slightly decreased
(-7) and contrast increased (+5) after scanning using Microsoft Office Picture
Manager.

Telescope: 10 inch f/5.7 Dobsonian and 6mm eyepiece 241x
Date: 3-17-2008 0:45 – 1:55 UT
Temperature: -0.8°C (31°F)
high cloud cover and high humidity, calm
Seeing:   Antoniadi III
Co longitude: 28.1°
Lunation: 9.3 days
Illumination: 77.2 %
  Phase:   57.0°
Observing Location: +41°37′ +87° 47′
 
Frank McCabe