Page 57 - BBC Sky at Night - September 2017 UK

THE SKY GUIDE SEPTEMBER 57

SATURN’S MOONS MERCURY Jupiter is too low for serious
BEST TIME TO SEE:
telescopic observation, located
SEPTEMBER 16 September, 18:00 BST in the evening twilight close to
(17:00 UT)
the west-southwest horizon
ALTITUDE: 7.5º (low)
LOCATION: Leo just after sunset. A thin, 6%-lit
waxing crescent Moon is 5º
Using a small scope you’ll be DIRECTION: East above and left of Jupiter on
able to spot Saturn’s biggest
moons. Their positions change Mercury is a morning object the evening of 22 September.
dramatically during the month, that has a close encounter with
as shown on the diagram. The mag. +1.4 Regulus (Alpha (_) SATURN
line by each date on the left Leonis) on the 10th. Mag. +0.2 BEST TIME TO SEE:
represents 00:00 UT. Mercury appears 38 arcminutes 1 September, from
from the star. After greatest 20:45 BST (19:45 UT)
western elongation on the 12th ALTITUDE: 14º
DATE WEST EAST
(Mercury will be 17.9º from the LOCATION: Ophiuchus
1
Sun) the planet swings sunwards, DIRECTION: South
2 chasing Mars as it goes. As it Saturn is past its best for 2017
enters a brighter part of the and during September slowly
3
sky, Mercury compensates by dims from mag. +0.4 to +0.5.
4 appearing brighter itself. On A scope will shows the planet’s
the 19th, at mag. –0.9, it shares beautiful rings currently tilted
5
the sky with mag. +1.8 Mars over by 27º. The planet is 3.5º
6 and mag. –3.8 Venus, 2º and below a 37%-lit waning crescent
12º west respectively. You may Moon on the evening of the
7
also be able to see a 1%-lit waning 26th; look low in the southwest
8
crescent Moon 3.6º east of the around 21:00 BST (20:00 UT)
9 planet just before sunrise. On
the 23rd, it is mag. –1.1 and sits URANUS
10
at one end of a line also formed BEST TIME TO SEE:
11 by Mars, Jupiter and Regulus. 30 September, from
02:20 BST (01:20 UT)
12
VENUS ALTITUDE: 47º
13 BEST TIME TO SEE: LOCATION: Pisces
1 September, from DIRECTION: South
14
04:00 BST (03:00 UT) Uranus is well placed and
15 ALTITUDE: 5º (low) reaches its highest point in the
LOCATION: Cancer sky in darkness all month. It’s
16
DIRECTION: East-northeast mag. +5.7 and approximately
17
On the 1st, mag. –3.9 Venus is 1º north of mag. +4.3
18 1.5º south of the centre of the Omicron (k) Piscium.
Beehive Cluster, M44 in Cancer.
19 It’s a spectacular sight through NEPTUNE
20 binoculars or a telescope using BEST TIME TO SEE:
a low power. Telescopically 5 September,
21
Venus appears 11.7 arcminutes 01:08 BST (00:08 UT)
22 across on 1 September, with a ALTITUDE: 29º
23 phase of 88%. On the 20th it LOCATION: Aquarius
passes mag. +1.4 Regulus (Alpha DIRECTION: South
24 (_) Leonis), by less than 0.5º. At Neptune reaches opposition

25 month end, Venus is 3.3º from on 5 September and remains
Mars and, through a telescope visible all night long for most
26 appears 11 arcseconds across of the month. By month end
27 and 90% lit. Neptune is 39 arcminutes
southeast of mag. +3.7 Lambda
28
JUPITER (h) Aquarii. Binoculars are
29 BEST TIME TO SEE: required to see the mag. +7.8
22 September, 19:20 BST planet; a telescope will show
30
18:20 UT its tiny 2.3-arcsecond disc and
1 ALTITUDE: 4º (low) its blue hue. The full Moon
LOCATION: Virgo on 6 September will be 2.3º
3 2 1 0 1 2 3 DIRECTION: West-southwest southwest of Neptune.
arcminutes
Tethys Dione Rhea Titan Iapetus Saturn YOUR BONUS CONTENT Planetary observing forms

skyatnightmagazine.com 2017