Sky and Telescope - June 2015 - 55

Contributing Editor Charles A. Wood (www2.lpod.org) also studies
the cratering record of another moon, Saturn's Titan.

Chang'e 3
on the lunar
surface, as
seen by a
camera on its
rover, Yutu, on
December 22,
2013. It was
the ﬁrst soft
lunar landing
since 1976.

CHINESE ACADEMY OF SCIENCES

secondary-school educator, and GRAIL team member.
(The International Astronomical Union will formally
consider the request later this year.)
The ridge is inconspicuous but not too hard to
observe. Start in familiar territory, the space between
Sinus Iridum and Plato, and then shift your view
poleward to the conspicuous fresh crater Philolaus
(71 km wide) and just beyond that to shallow, roughﬂoored Mouchez (83 km). Between these two features
lies Sally Ride ridge, which is probably a rim segment
of an ancient crater adjacent to Mouchez. According to
measurements from the Lunar Reconnaissance Orbiter's
QuickMap path tool (S&T: Aug. 2014, p. 54), the ridge is
about 40 km long and rises about 2½ km above its surroundings.
The landing site for the Chang'e 3 mission is easier to
ﬁnd. In this case start at the northwestern end of Mare
Imbrium with the twin small craters Helicon (24 km)
and Le Verrier (21 km). Now look halfway between Le
Verrier and Montes Recti (Straight Range); that ﬂat
mare is where Yutu sits in its tracks, its carrier craft
about 80 feet (25 meters) away.
The region is not quite featureless: a broad, slightly
dark lava ﬂow extends from the west to the Chang'e 3
landing area, whereas lavas to the east are slightly paler
and older. Yutu's ground-penetrating radar has detected
multiple layers - probably a sequence of lava ﬂows and
ejecta blankets - beneath the landing site (see page 14).
Observation of the LADEE crash site is impossible

Charles A. Wood

from Earth, even with the best telescopes, for it crashed
onto the farside. Originally, the location was unknown,
but LRO scientists discovered the small depression it
made near the crater Sundman V in the Orientale Basin
ejecta blanket. In fact, if you can see the large crater
Einstein when libration along the western limb is good,
the region beyond - almost visible -is the resting place
for LADEE.
The LRO team has done an excellent job tracking
down most of the spacecraft that reached the Moon.
Although all of the intact spacecraft and excavated
craters are far too small to see from Earth (Ebb and Flow
gouged out pits each about 5 m wide), it's fun to follow
up your telescopic views of these regions with a trip to
the LRO landing-site webpage (featured-sites.lroc.asu.
edu) to see what only a future lunar tourist might be able
to observe. ✦

Ebb and Flow

The Moon * June 2015
21

Phases
Chang'e 3

Distances

June 2, 16:19 UT

Perigee
229,728 miles

June 10, 5h UT
diam. 29′ 38″

LAST QUARTER

Apogee
251,116 miles

June 23, 17h UT
diam. 32′ 17″

FULL MOON

June 9, 15:42 UT
NEW MOON

June 16, 14:05 UT
FIRST QUARTER

June 24, 11:03 UT

Librations
Cabeus (crater)
Hausen (crater)
Mare Humboldtianum
Vallis Baade

June 4
June 9
June 21
June 30

For key dates, yellow dots indicate which part of the Moon's
limb is tipped the most toward Earth by libration under favorable illumination.

30
June 4
9
NASA / LRO

Sk yandTelescope.com June 2015

http://www2.lpod.org http://featured-sites.lroc.asu.edu http://featured-sites.lroc.asu.edu http://www.SkyandTelescope.com

Sky and Telescope - June 2015

Table of Contents for the Digital Edition of Sky and Telescope - June 2015