Ammonius (crater)
Encyclopedia
Ammonius is a bowl-shaped lunar
impact crater
with a slightly raised rim. It is located on the floor of the walled plain Ptolemaeus
, about 30 kilometers northeast of the crater mid-point. In the past this crater was identified as Ptolemaeus A, before being named by the IAU
.
Just to the north on the lava
-flooded floor of Ptolemaeus is a relatively prominent "ghost" crater
: the discernible buried rim of a pre-existing crater. The diameter of this ghost crater is nearly double that of Ammonius, and is currently identified as Ptolemaeus B.
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...
impact crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
with a slightly raised rim. It is located on the floor of the walled plain Ptolemaeus
Ptolemaeus (lunar crater)
Ptolemaeus is an ancient lunar impact crater close to the center of the near side. To the south-southeast Ptolemaeus is joined to the rim of the crater Alphonsus by a section of rugged, irregular terrain, and these form a prominent chain with Arzachel to the south...
, about 30 kilometers northeast of the crater mid-point. In the past this crater was identified as Ptolemaeus A, before being named by the IAU
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
.
Just to the north on the lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...
-flooded floor of Ptolemaeus is a relatively prominent "ghost" crater
Palimpsest
A palimpsest is a manuscript page from a scroll or book from which the text has been scraped off and which can be used again. The word "palimpsest" comes through Latin palimpsēstus from Ancient Greek παλίμψηστος originally compounded from πάλιν and ψάω literally meaning “scraped...
: the discernible buried rim of a pre-existing crater. The diameter of this ghost crater is nearly double that of Ammonius, and is currently identified as Ptolemaeus B.