Venus slides past the Beehive Cluster36 ASTRONOMY • JUNE 2015Visible to the naked eye
Visible with binoculars
Visible with a telescopeMARTIN RATCLIFFE and ALISTER LING describe the
solar system’s changing landscape as it appears in Earth’s sky.June 2015: Venus meets Jupiter at dusk
lthough June nights
are the shortest of the
year in the Northern
Hemisphere, in 2015
they pack a power-
ful punch. Venus and Jupiter
will top most observers’ lists
by dominating the evening
sky all month. Keep a watch
on the two brightest planets
as the weeks pass, and you’ll
notice them pulling closer. The
drama builds to a stunning
climax when they pass within
0.3° of each other as the calen-
dar turns from June to July.
But the thrills don’t stop
there. June also features SaturnPollux. The inner world
crosses into Cancer the Crab
on June 3. It reaches greatest
elongation three days later,
when it lies 45° east of the Sun
and sets after 11:30 p.m. local
daylight time. Venus slides less
than 1° north of the Beehive
star cluster (M44) June 12 and
13, making a splendid sight
through binoculars. The best
views will come about an hour
after sunset, before the planet
dips too low.
As Venus pulls within 7° of
Jupiter on June 19, a crescent
Moon joins the scene some 7°
below Venus. Compare our
satellite’s 13-percent-lit disk
to a telescopic view of Venus’
fatter crescent, which is 42
percent lit. The next evening,
the waxing Moon lies 5° to
Jupiter’s lower left.
Venus crosses into Leo the
Lion on June 25. The separa-
tion between it and Jupiter has
now shrunk to 3°, and the bril-
liant planets look like a pair of
cat’s eyes catching a car’s head-
lights in the dark. The gap
keeps closing over the next five
nights, reaching a minimum of
just 20' (two-thirds of the FullSKYTHIS
MONTH
A
just a few weeks past its peak,
Uranus and Neptune coming
into sharper focus after mid-
night, and Mercury making a
brief appearance before dawn.
June’s first evening reveals
two brilliant planets lighting
up the western sky. Venus
and Jupiter stand 20° apart
that night. Although Venus
appears lower, it shines 10
times brighter than its com-
panion (magnitude –4.4 com-
pared with magnitude –1.9).
You’ll spot Venus easily
within 30 minutes of sunset,
when it appears 30° above the
horizon. A half-hour later, the
planet is a stunning jewel set
against the darkening sky.
Venus lies among the
background stars of eastern
Gemini on the 1st, forming a
straight line with the Twin’s
brightest stars, Castor andMoon’s diameter) on the 30th.
Both planets will appear in a
single field of view through a
telescope at low power.
Although conjunctions
between Venus and Jupiter
typically occur every year or
two, this event is the first and
closest in a rare triple con-
junction. The second occurs
July 31 in the evening sky and
the third October 26 before
dawn. An even closer con-
junction (4' separation) comes
August 27, 2016, but the pair
then will be in bright twilight.
If you want to view Venus
through a telescope, do so
before darkness fully settles
in. Twilight reduces the stark
contrast between the planet
and sky and makes detail
stand out. On June 1, Venus
appears 22" across and just
over half-lit. It reaches 50 per-
cent illumination at greatest
elongation on the 6th, when it
resembles a miniature First
Quarter Moon. By month’s
end, the planet’s disk spans
32" and is about one-third lit.
As with Venus, Jupiter
benefits from early evening
observing. The giant planetBrilliant Venus passed a few degrees to Jupiter’s upper right in evening
twilight March 14, 2012. The two worlds will appear even closer during a
return engagement in late June. JAMIE COOPERThe stars of the Beehive Cluster (M44) made a stunning backdrop for Venus
on July 3, 2013. The planet revisits the cluster June 12 and 13. LUIS ARGERICHMartin Ratcliffe provides plane-
tarium development for Sky-Skan,
Inc., from his home in Wichita,
Kansas. Meteorologist Alister
Ling works for Environment
Canada in Edmonton, Alberta.