24 April 2015

Ancient Thebit, Rima Birt and Rupes Recta



By  Avani Soares
( http://www.astroavani.no.comunidades.net/ )

 
The absolute best example of a lunar fault is found along the eastern shore of Mare Nubium - the straight wall or Rupes Recta.
 This lunar feature is known by a thin long line that never fails to impress; even casual observers lunar can enjoy this magnificent training.
 The view is better when the sun rose on it and the terminator is a little to the west in the center of Mare Nubium. Accordingly,
 the wall casts a shadow which extends along all its length 120km.
 This demonstrates dramatically that the lunar surface should be lower on the west side of the fault than the east.
Several authors have reported that the slope is 250-300 meters high, but the latest
measures through the drop shadow suggest that there may be up to 450 m above the floor of the western basin.
Despite appearances, the straight wall is not a cliff, although it is relatively steep, towering
 above the plain at an angle slightly greater than 20 °.

The narrow part of the wall, (traditionally called Railway by British observers) is now officially known as Rupes Recta
and ends in the south against a bunch of short ridges segments in the 17th century the Christiaan
Huygens selenógrafo compared to the hilt of a sword, with the line straight wall with the blade.

If you expand your vision, you will notice the slices of walls through the flooded floor of an old lava and
unnamed crater in ruins my friend Charles Wood calls "Ancient Thebit", and the very Thebit with 57 km wide is located
 on the right bank of the photo. The rim 200 km wide this ancient Thebit (indicated by the dotted orange line)
is well defined, but its western border is marked only by wrinkle ridges arc-shaped.

Although some researchers have noted that Rupes Straight is approximately radial to the Imbrium basin,
 and thus perhaps related to it, it is very clear that has a much closer relationship with the former Thebit.
Wood believes that AntigaThebit was formed at the edge of Nubium impact basin and the west wall of the crater was eventually buried
by lava flows that flooded the basin. This is essentially the same sequence as occurred in the
 Sinus Iridum Imbrium basin and  Fracastorius Nectaris the edge of the bowl. A good portion of the Old Thebit the floor gave way
 to accommodate the sinking of the basin. This is again very similar to Fracastorius, which is cut by a delicate slit where the floor sank.

Finally, if you look carefully in good viewing conditions, you should see a small rille parallel to Rupes Line,
 west and north of the bright crater Birt. Each end of this rille, known as Rima Birt, ends in a small cave called Birt "E" and "F".
Rima Birt is a challenge for amateur observers and scientists trying to explain why he is there. Due to small cave at the north end
 of the rille stay close to the edge of the Old Thebit, we can speculate that the fractures associated with the rim formed an easy
path to the lava erupt on the lunar surface, producing a dome collapses,
a lava channel and perhaps a small deposit of ash and debris propelled by gas.

Small craters indicated by capital letters, are satellite craters of Birt and Thebit.

Source: Charles Wood - Sky & Telescope

Adaptation: Avani Soares

 

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