  Observations of 12CO(3-2) emission of the circumbinary envelope of Mira Ceti,
made by ALMA are analysed. The observed Doppler velocity distribution is made
of three components: a blue-shifted south-eastern arc, which can be described
as a ring in slow radial expansion, ~1.7 km/s, making an angle of ~50 deg with
the plane of the sky and born some 2000 years ago; a few arcs, probably born at
the same epoch as the blue-shifted arc, all sharing Doppler velocities
red-shifted by approximately 3 +/- 2 km/s with respect to the main star; the
third, central region dominated by the circumbinary envelope, displaying two
outflows in the south-western and north-eastern hemispheres. At short distances
from the star, up to ~1.5", these hemispheres display very different
morphologies: the south-western outflow covers a broad solid angle, expands
radially at a rate between 5 and 10 km/s and is slightly red shifted; the
north-eastern outflow consists of two arms, both blue-shifted, bracketing a
broad dark region where emission is suppressed. At distances between ~1.5" and
~2.5" the asymmetry between the two hemispheres is significantly smaller and
detached arcs, particularly spectacular in the north-eastern hemisphere are
present. Close to the stars, we observe a mass of gas surrounding Mira B, with
a size of a few tens of AU, and having Doppler velocities with respect to Mira
B reaching +/-1.5 km/s, which we interpret as gas flowing from Mira A toward
Mira B.
