Bx

Helicon

Dome near Prim Lap/see (cropped from 7065..I L

Lambert to Sinus Iridum

2005.04.10 13:1+UT Age 10.7 days 10-ln fffi Newtonian + 2.5X + ToUcam

The wrinkle ridges on the floor of Sinus Iridum are particularly prominent when the terminator passes over them. To emphasize the profile of these ridges, Montes Jura (the mountain range under illumination) is inevitably over-exposed in Image T065. Sunlight comes from the east, suggesting that an observer on the shore of Sinus Iridum would experience sunrise at this time.

Helicon is a crater resembling a bowl, 24 km in diameter and 1900 m deep. The cape-like feature that casts triangular shadow is Promontorium Laplace. It rises 2600 m high and has an indistinctive dome in the west (T065A). Other domes exist near Promontorium Heraclides (T174), but they are noticeable only under very low illumination angles.

Copernicus, Eratosthenes, Stadius, Montes Carpatus, Euler, Lambert, Hortensius, Milichius

Hatfield 5

9.70 N

2002.11.14 14:58UT Agss 9 days. C9+LE12.5 + GP990 1/7 sec DSCN5818

(Image T027)

Copernicus 20.10 W

Copernicus is a fine example of a young ring mountain, formed about 800 million years ago. It is located between the south of Mare Imbrium and the north of a loosely bounded plain named Mare Insularum (Sea of Isles). Copernicus is 93 km in diameter, with a group of central peaks and terraced walls 3700 m above the floor. The depth-diameter ratio of Copernicus is 1:25; this makes the crater to resemble a pie pan rather than a bowl. The Copernicus region is rich in observation details. At Moon age of 9 ~10 days, a faint dome is barely notable about one diameter west of the crater. Numerous secondary craterlets and pits also spread like raisin holes in the north-east vicinity. Extensive bright rays emit from the crater at days close to the full moon.

2002.11.14 14:58UT Agss 9 days. C9+LE12.5 + GP990 1/7 sec DSCN5818

The number of central peaks in Copernicus is a challenge to observation. Three peaks of height up to 1200 m are obvious in small telescopes. Large telescopes may spot additional small "bumps". Images from spacecraft, however, reveal even more peaks. The terraced walls look somewhat hexagonal. The radial scars around the outer walls are the ejecta blanket resulted from an asteroid-like impact. The two small overlapping craters in the south of Copernicus are Fauth (12 km) and Fauth A (10 km); they are good indicators to align an image's north-south orientation.

(Image T205, next page)

Outside the rim of Copernicus are two small craters surrounded by dark halo — Copernicus H, diameter 5 km and Gay-Lussac N, diameter 2 km. Presumably these craters formed from secondary impact, the dark halo could be the deposits of mare basalt excavated from the impact site. The impact was supposed not too energetic, so only the top-most layer of dark basalt was excavated but the deeper underground of light-colored anorthosite remained intact.

Reinhold B

Copernicus

Gay-Lussac N

Copernicus 2005.04.19 -12:39UT Age 10.7days. 10-in 1/6 Newtonian + 2.5X + 1.6X + TcUcam (mosaic)

Copernicus on the terminator 2007.10.20 12:57 UT Age 9.4 days 10-in f/6 Newtonian + Meade 2X +■ ToUcam

terraced \/ walls

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