HERCULESCORONA BOREALISBOÖTES
ArcturusURSA MINORPolarisURSA MAJORRadiant10°June 27, 2 A.M.
Looking northwestJune Boötid meteor showerSchickardWWW.ASTRONOMY.COM 37then lies higher in the sky, so
its light passes through less
of Earth’s image-distorting
atmosphere. For the same rea-
son, early June offers superior
views because Jupiter lies
more than a third of the
way to the zenith an hour
after sunset.
Once you’ve sampled the
delicate details in Jupiter’s
cloud tops — the alternating
series of bright zones and
darker belts, turbulent eddies,
and giant storms — turn your
attention to the planet’s four
bright moons. These so-called
Galilean satellites orbit Jupiter
with periods ranging from 1.8
to 16.7 days. Because both
Earth and the Sun now lie in
the plane of the orbits, one
moon may cross in front of
another (an occultation) or
pass through another’s
shadow (an eclipse). Unfor-
tunately, the current series
of mutual events is winding
RISINGMOON
METEORWATCH
One lunar feature nicely encap-
sulates much of the Moon’s his-
tory. The crater Schickard stands
out near the southwestern limb
in the days around Full Moon
(June 2 this month). Your eyes
will thank you if you reduce the
lunar disk’s excessive glare.
Using a smaller telescope than
usual, pumping up the magni-
fication, or screwing in a dark
filter will help.
To get the full effect of view-
ing Schickard, start observing
a couple of evenings early. On
May 30, the first rays of sunlight
strike the flooded crater at a
glancing angle, highlighting
differences in the heights of
smaller features. You’ll quickly
discern that this is an old crater
because its rim appears bat-
tered; in contrast, the smallercraters pocking the smooth
floor display the classic sharp
edges of relative youth.
Schickard’s western wall, which
would have been steep at the
moment of formation, abruptly
slumped down into terraces
that remain visible today. The
higher Sun on the following two
evenings seemingly erases
these features.
Schickard transforms into a
two-faced depression on the
following nights, with an
unusual stripe of lighter gray
material painted across the mid-
dle of the floor. A large impact
carved out this 132-mile-wide
crater some 4 billion years ago.
Lava soon welled up and cov-
ered its central peaks. Then the
giant Mare Orientale impact to
the west sprayed the wholeregion with lighter-colored
material. A final surge of lava
covered the northern and
southern portions of the bowl
but did not rise high enough to
erase the lighter stripe.When the Sun returns to the
crater June 28, it displays dra-
matic shadows that camouflage
the different shades. Within a
couple of days, however, the
stripe returns to prominence.Northern Hemisphere meteor
observers face two obstacles dur-
ing June. First, the month delivers
the shortest nights of the year,
with areas north of 50° north lati-
tude never achieving complete
darkness. Second, June offers no
major meteor showers.
This month’s best minor shower
is the June Boötids, which peaks
June 27. Astronomers don’t expect
much activity this year, but you
won’t know if you don’t look. The
waxing gibbous Moon sets around
2 A.M. local daylight time on the
27th, leaving an hour or two of
darkness for those at mid-northern
latitudes. June Boötid meteors hit
Earth at “only” 11 miles per sec-
ond, the slowest of any shower.Punched, flooded, sprayed, and strafed
The Herdsman’s laid-back shooting stars
— Continued on page 42June Boötid meteors
Active Dates: June 22–July 2
Peak: June 27
Moon at peak: Waxing gibbous
Maximum rate at peak:
Highly variableObservers should be on the lookout for the slow-moving meteors of the
June Boötid shower, which peaks June 27. ALL ILLUSTRATIONS: ASTRONOMY: ROEN KELLYCatch lunar history on display when the Sun illuminates 132-mile-wide
Schickard Crater in the days around Full Moon.Venus reaches its peak June 6, when it lies 45° from the Sun and
appears some 25° above the western horizon an hour after sunset.OBSERVING
HIGHLIGHTNESchickardCO NSO LI DATED LU NAR ATL A S/UA/LPL; INSET: NASA/GSFC/ASU