48 July 2014 sky & telescopeOBSERVING
Sun, Moon && PlanetsTwo Close Conjunctions
The Moon passes very close to Mars and Saturn in July’s evening sky.
Shortly after sunset on the fi rst few
evenings in July, you may still glimpse
Jupiter low in the Sun’s afterglow. All
month, Mars and Spica shine together
in the southwest or west in the evening.
Saturn, to their left, shines a little higher
and sets a little later.
As July’s very early dawns begin to
brighten, fi rst Venus and then Mercury
nudge up low in the east.DUSK
Jupiter begins July setting about an
hour after the Sun for observers at mid-
northern latitudes. But Jupiter appears a
half degree lower each evening, so it’s lost
from view early in the month. The giant
planet reaches conjunction with the Sun
on July 24th.Dusk, June 30–July 2
1 hour after sunsetRegulusDenebolaMoon
June 30Moon
July 1Moon
July 2Looking West10 ° LEO
γDusk, July 4 – 6
1 hour after sunsetSpicaMars, very
near the
Moon!Moon
July 4Moon
July 5Moon
July 6Looking SouthwestCORVUSγ VirDusk, July 7– 8
1 hour after sunsetAntaresSaturn
Moon
Moon July 7
July 8Looking SouthSCORPIUSLUPUSβ Libβ α LibδEVENING
Mars fades from magnitude 0.0 to +0.4
in July but still easily outshines nearby
1.0-magnitude Spica. Orange-yellow Mars
is moving eastward with direct motion
in July. On the American evening of July
13th it has its third and fi nal conjunction
of the year with bluish-white Spica. This
conjunction is much tighter than the fi rst
two, with Mars passing just 1.3° to Spica’s
north-northeast.
Mars shrinks from 9.5′′ to 7.9′′ in angu-
lar equatorial diameter this month, too
small to glimpse more than a few surface
features through a telescope. Mars comes
to eastern quadrature, 90° east of the Sun,
on July 19th, so it shows a slight gibbous
phase this month. The planet is already
past its highest point in the sky at sunset,so it’s best observed while still relatively
high in late twilight. Mars starts setting
before midnight (daylight-saving time)
around mid-month.
Saturn lingers in western Libra
near the wide double star Alpha Librae
(Zubenelgenubi) this month, dimming
a bit from +0.4 to +0.5. The rings are at
this year’s minimum tilt of 21°, but that’s
still rather large. On July 21st Saturn halts
retrograde motion and resumes direct
(eastward) motion against the background
of stars. But much faster Mars, though
still over in Virgo, continues to close the
gap between itself and Saturn: from 28° to
14 ° in July. Mars will catch up to Saturn on
August 25th.
The 7th-magnitude asteroid Vesta
passes an amazingly small 0.17° south-