44 BBC Sky at Night Magazine August 2021
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Family stargazing
Observing a favourable appearance of the Perseid
meteor shower can be a summer-holiday treat that will
be remembered for a long time. Dealing with a night
observation can be tricky for youngsters, so schedule sleep from
early evening to midnight BST on 12 August. Then go out and
meteor watch (see page 46) until 03:30 BST (02:30 UT) on the
13th. A sun lounger with a sleeping bag creates a warm platform
to observe from. In the quiet periods between meteors, you can
identify some of the stars and constellations with our all-sky
chart on page 50. http://www.bbc.co.uk/cbeebies/shows/stargazingAUGUST HIGHLIGHTS
Your guide to the
night sky this monthTuesday
This evening
and tomorrow
evening, the
waxing crescent
Moon – visible shortly after
sunset – will be close to the
mag. –3.9 planet Venus.10
Monday X
Saturn is at
opposition today.
A phenomenon known
as the ‘opposition effect’
causes the planet’s rings to
brighten and this should be
noticeable through a telescope.This morning’s 35%-lit waning
crescent Moon sits 6.7Ō south
of the Pleiades.2
Friday
Starting at
02:50 BST
(01:50 UT), Io and
its shadow will
begin to cross Jupiter’s disc.
As this is close to Jupiter’s
opposition and we’re just
past Jupiter’s equinox, the
satellite’s body will overlap
its shadow. More on page 47.20
Thursday
Jupiter is at
opposition today.
A telescope view of
the gas giant as it
approaches the west-southwest
horizon will show the moons Io
and Ganymede just 2 arcseconds
apart at 05:15 BST (04:15 UT).
See page 47 for more.19
W Thursday
As this morning’s
12 %-lit waning
crescent Moon rises,
it’ll be passing over
the northern portion of
open cluster M35. The
event concludes around
02:40 BST (01:40 UT).5
Sunday X
An unusual
occultation of Europa
by Ganymede occurs at
23:00 BST (22:00 UT) this
evening. The relative motion
of both moons means that
Ganymede appears to cover
part of Europa, which then
appears to pull away again.
See page 47 for more details.1
Wednesday
Mag. –0.41
Mercury lies low
above the western
horizon shortly after
sunset. Not so obvious is mag.
+1.8 Mars, just 20 arcminutes
east of Mercury this evening,
the bright evening twilight
making it a challenge to see.18
Saturday
This evening’s
full Moon
represents the
Moon at opposition.This evening between
21:15 BST (20:15 UT)
and 23:35 BST (22:35 UT) Io
and its shadow will transit
Jupiter’s disc. See page 47.21
Tu e s d ay
A telescopic
view of the
morning Moon at
04:30 BST (03:30
UT) will show a less common
clair-obscur effect known as
the ‘Zeno Steps’, which is caused
when the evening terminator
is near the 18km-crater Zeno E
on the lunar northeast limb.24
Monday
Io and
Ganymede
transit Jupiter’s
disc, accompanied
by their shadows. The event
starts at 21:00 BST (20:00 UT)
with Io starting to transit, and
ends at 04:22 BST (03:22 UT)
as Ganymede’s shadow slips
off Jupiter’s disc. See page 47.30