46 AUSTRALIAN SKY & TELESCOPE April 2019
midnightatthestartofApril,andby
just after 10:00pm at month’s end. The
ringed world can be found amongst the
starsofSagittariusand,likeJupiter, will
reachitsstationarypointthismonth
—onthe30th—beforecommencing
fourandahalfmonthsofretrograde
motion.
The eastern half of Australia will
be treated to alunar occultationof
SaturnonthenightofApril25.Alunar
occultation occurs when the Moon
movesinfrontofabackgroundobject,
whetherthatbeastar,aminorplanet
or,inthiscase,amajorplanet.(To
‘occult’simplymeanstomake‘dark’.)
Often when the Moon occults a planet,
you’ll see the planet disappear as the
Mooncoversitupduetoitsorbital
motion, and then some time later
you’ll see it reappear on the opposite
lunar limb. But sometimes you’ll only
seeoneortheother—forinstance,SUN, MOON & PLANETS by Jonathan NallyThe Moon swallows Saturn
The first of four lunar occultations of the ringed planet in 2019.
T
his is a great time for viewing
Mercury (mag. 0.2, 7.7 ̋ mid-
April), with the innermost planet
reaching its greatest elongation west
(28°) on the 12th. As the ecliptic is
almost vertical with respect to the
horizon, the planet will rise high and
shine brightly in the pre-dawn sky. Look
for the Moon nearby on the 3rd and
then, on the 17, you’ll see Venus close
by too as the two planets close up.
Speaking of Venus (–3.9, 12 .3 ̋), it
too is a bright object out to the east in
the pre-dawn sky. Look for the Moon
nearby on the 2nd. As mentioned above,
both it and Mercury will come close on
the 17th, around 4° apart.
Mars (1.5, 4.4 ̋) is low in the western
sky after sunset this month. Located in
Taurus, you’ll find it sidling up to the
Hyades star cluster, joined by the Moon
onthe9th.Ifyouhavebinoculars,take
alookonthe13thwhentheplanetwillSMercury,Venuscloseinthemorning. SMars in Taurus in the evening. SJupitershinesinthelateevening.beclosetothedoublestarsKappa^1 /
Kappa^2 Tauri (comprising 4th- and
5th-magnitude stars). Then, on the 19th
it will come close to Tau Tauri (4th- and
7th-magnitude stars). The Red Planet
appears tiny now through the telescope,
compared to its closest-approach size of
last year.
King of the planets, Jupiter (–2 .3,
41.6 ̋) rises about 10:00pm at the
beginning of April and around 8:00pm
by the end of the month. The planet
will be ‘stationary’ on April 11 and
then begin four months of retrograde
motion (a line-of-sight effect caused
primarily by the Earth ‘overtaking’ it on
our planet’s inside orbit). This motion
will take place against the backdrop of
the Milky Way, making for some very
fine binocular views and photographic
opportunities indeed. Look for the
Moon nearby on the 19th.
Saturn(0.5, 16.7 ̋)risesabout