Page 53 - BBC Sky at Night - September 2017 UK

THE SKY GUIDE SEPTEMBER 53

Mercury meets Mars Mercury and Mars appear to converge.
Visible approximately 90 minutes
before sunrise low in the east, on
WHEN: Closest approach occurs in the morning skies of 16 and 17 September 15 September, mag. +3.8 Rho (l) Leonis,
mag. +1.8 Mars and –0.6 Mercury form
16 Sep 17 Sep 18 Sep Mercury, Venus, Mars and a right-angled triangle, with Mars at
Mercury Mars the Moon line up on the 17th; the right-angle. The planets appear
Mars this will be the view at 05:40 1.2º apart at this time.
BST (04:40 UT). Mars and
Mars Mercury Mercury’s positions are inset On 16 September the separation
Mercury will be 28 arcminutes, with Mars,
Mercury and Rho Leonis now forming a
Moon thin isosceles triangle. If you can keep
17 Sep with the planets as the Sun rises, under
very clear skies it may be possible to follow
them in daylight as they continue to
converge. As they approach their setting
Venus
point around 19:00 BST (18:00 UT,
times for the centre of the UK) they
Moon will appear just 3.5 arcminutes apart.
18 Sep
On 17 September the apparent
Mars separation is 20 arcminutes. By the
Mercury 17th, Mercury will have brightened to
mag. –0.8 making it easier to spot despite
losing altitude. On 18 September, the
ENE E celestial meeting ends, the apparent
separation having increased to 1.2º.
Mercury rises approximately the pair, you’ll also want to catch the Although it’s not impossible, it’s
90 minutes before the Sun on spectacular meet-up between Regulus unusual to have perfectly clear skies for
10 September and should be and Venus on 20 September. morning observing sessions during
relatively easy to see at mag. +0.2. On this On 10 September, mag. +1.8 Mars September. Despite this, having a range
date it is 38 arcminutes south-southwest can be seen 3º east of Regulus. From of dates to pick from will hopefully
of mag. +1.4 Regulus (Alpha (_) Leonis). the UK this places it below and left of ensure you see something of this
If you manage to take a photograph of the star. Over the next few mornings impressive early morning show.

Comet 24P/Schaumasse and the Beehive

WHEN: 24-26 September, from 04:00 BST (03:00 UT)

Venus is The cluster rises above 2 2 Sep
not the only the northeast horizon just
Solar System after 01:30 BST (00:30 UT) 2 3 Sep
object passing close to the and manages to attain an Comet 24P/Schaumasse d
Beehive Cluster in Cancer, altitude of about 30º at
2 4 Sep
M44, this month. Comet 24P/ 05:00 BST (04:00 UT) in
Schaumasse is also in the a dark sky, astronomical a
vicinity, travelling in front of twilight beginning shortly
2 5 Sep
the northern part of the cluster after this time.
between 24-26 September. On 24 September at
When Venus passed south 04:00 BST (03:00 UT), the 2 6 Sep
of the cluster at the start of comet is 1º to the northwest ¡
the month the stars of the of the cluster’s centre. On
Beehive were completely the morning of 25 September, 2 7 Sep M44
outshone by the blazing the apparent separation
light of the planet. With will have decreased to just
2 8 Sep
24P/Schaumasse the tables 0.5º, the comet lying due
are turned because the comet north of the cluster’s CANCER
is predicted to be a 12th- centre. Then on the b
magnitude object at this morning of 26 September, 2 9 Sep
time. This means that the separation will have
it’s best suited to at least an increased to 1º again, with
8-inch telescope or as a target the comet being found to Þ Comet 24P/Schaumasse will cut through the Beehive Cluster,
for astrophotography. the east-northeast. appearing as a faint smudge passing between the sharp cluster stars

skyatnightmagazine.com 2017