Page 16 - BBC Sky at Night Beginners Guide to Astronomy - 2017 UK

NEED TO KNOW

❯ TARGET 1: M31
M31, the Andromeda
Galaxy, is one of the most
distant objects you can see
with your own eyes from 6
a dark location. This is 5
an unaided-eye route, but 4
trying it with binoculars
shows the difference that increased magnifi cation 3 1
makes. The best time to attempt this is in the autumn, 2
when it gets dark early.
So in mid-October at 9pm, this six-stop hop starts
at Alpheratz, the top-left star in the Great Square of
Pegasus asterism (1). Move to the next star to the left,
Delta (b) Andromedae (2). Now move left again, but
slightly higher, to Beta (`) Andromedae (3). The next
hop is to the star directly above, Mu (+) Andromedae
(4), and then directly above that again, to the star Nu
(i) Andromedae (5). A few fi nger-widths diagonally
right of this is the smudge of M31 (6).

❯ TARGET 2: M27
Next, we’re going to use
binoculars to hop in fi ve 4
steps from the Summer
Triangle asterism, which in 3 5
mid-October is high in the
southwest at 9pm, to M27, 2
the Dumbbell Nebula.
Begin at Altair, the lowest star of the Summer
Triangle (1). Look a short distance (about 10º) upwards
from Altair and you will come across the small, fi ve-star
constellation Sagitta, named for its appearance as
an arrow. From the left-most star in Sagitta, Eta (d)
Sagittae (2), follow a chain of fainter, mag. +6 and
+7 stars northwest (3) until you arrive at mag. +5.5 14
Vulpeculae (4). You may well have found M27 already 1
– it’s to the lower left of this star (5).
Note that at other times of the year, the starhopping
directions will shift somewhat, because of the rotation
of the Earth.

❯ TARGET 3: M11
The Wild Duck Cluster, M11, 1
is a fi ne object in binoculars
– and it will look even better
through a telescope. Getting
there, however, needs
nothing more than a four-stop
hop that you can navigate 2
with the naked eye.
Once again, start from the Summer Triangle’s
PETE LAWRENCE X 3, THINKSTOCK X 2 Aquilae (2), then down the same amount again, but 3 4 6 5
southernmost star, Altair (1), at 9pm in mid-October.
Move your gaze down and right 15º to Delta (b)

not so much to the right, until you get to Lambda (h)
Aquilae (3). Now hop down to Eta (d) Scuti (4), the
right-most of the two fainter stars that you’ll see trailing
off to the right of Lambda. Train your binoculars just
below the mid-point between this star and Beta (`)
Scuti to the right (5), and there is M11(6).

16 skyatnightmagazine.com 2012