Impressions of the Southern Sky: Part I

I have recently returned from a 2-week trip to Chile. The primary
impetus for the trip was to observe the southern skies for the first
time in my life, but a second and very important purpose was to
see the land underneath those skies, this being my first visit to
South America. For the moment, I will omit mention of my daytime
activities and of the logistics w.r.t. the observing; those may be
the subject of another article.

As it happens, this was my second visit to the southern hemisphere,
my first being a trip to Australia and New Zealand some twenty years
ago. But for whatever reason, my only astronomical impression from
that trip is the striking image of Orion high in the sky and upside-
down from our north-centric perspective. It seems a little odd in
retrospect; I certainly knew enough back then to have done at least
a little naked-eye observing, but I didn't. So on this trip to
Chile, essentially everything south of declination 40S was totally
new to me.

I brought my 10x50 binoculars and my 100mm F/6 achromat on a
(very) lightweight alt-az mount. In addition, I had a few chances
to use much bigger scopes, ranging from 12 to 16 inches. On the
whole, this was pretty much ideal for this trip. The 100mm scope
is big enough to show quite a lot of stuff well; in particular,
it is excellent for many open clusters and nebulae. On the other
hand, it is also small enough so that I was not overwhelmed, and
its FOV is wide enough so that I could survey most of the sky.
But there were a few objects that I wanted to see in much more
detail than a 100mm scope allows, notably 47 Tucanae, the
Tarantula Nebula, and the Eta Carina Nebula, and in fact, I got
a chance to see all of those through much more appropriate scopes.

I observed for two short evenings, several long to very-long
evenings, one all night session, and one from 3AM to dawn. Of
the nights that I had set aside for astronomy, one was clouded
out and one seemed iffy but in fact worked out OK. I observed
at various sites from latitude 32S to 26S, and altitudes from
3,000 to 12,000 feet. Except for the night that was clouded
out, the transparency ranged from excellent to amazing. My
naked-eye views of M31, skimming 15 degrees above the northern
horizon, were as good as any I have had back home when M31 was
directly overhead. Seeing was not relevant for most of the
observing that I was doing, but on the whole, it was not as
good as it might be, and certainly not as good as it usually
is in this part of the world. Nonetheless, I had one of the
best views of Mars that I have had during this opposition,
despite the fact that Mars had shrunk to only 2/3 of its maximum
size. Having it nearly directly overhead is a huge help!

All other things being equal, the most natural time for a
northern observer to visit the southern hemisphere would be
in the austral autumn, around April or May, when the far-
southern Milky Way would be at its highest in the evening.
But the circumstances of my life dictated making the trip
in the asutral spring, which had its own unique advantages.
Above all, this is the ideal time to view three tremendously
important objects which are poorly placed during the austral
autumn: the two Magellanic Clouds, by far the closest galaxies
to our own, and the globular cluster 47 Tucanae (NGC 104),
which is much bigger and brighter than any other globular
cluster except for Omega Centauri. Those three objects were
the primary targets for my trip. In addition, I figured
that I could observe much of the far-southern Milky Way
either early in the evening or just before dawn. And
although they were placed about as poorly as they can be,
I wanted to see the Southern Cross, famous icon of the
southern sky, and the three closest stars to our own Sun:
Proxima Centauri and the two components of Alpha Centauri.
All of those are at declination 60S or farther south, making
them hard to view well anywhere in the northern hemisphere.

But wonderful as all of those objects proved to be, my most
vivid impression from the whole trip turned out to be an object
that I already knew well, or thought that I knew well. The
first evening that I stepped out of my cabin high up in the
Andes, still before the end of astronomical twilight and not
well dark-adapted, I was overwhelmed by the Milky Way,
tremendously broad and bright, and etched with dark lanes
as I had never seen it before. Right in the middle was a
huge cloud of dazzlingly bright light -- surely an open
cluster -- and near that, an asterism almost identical to
the constellation Sagittae in size and shape, but much brighter.

Only about half an hour later, after I had sat down to orient
myself to the unfamiliar constellations, did I realize that I
knew that part of the sky perfectly well. I was looking at the
broadest and brightest part of the Milky Way, in Sagittarius
and Scorpius, which I am used to seeing disappearing into the
trees, but which here formed the highest part of a great arch
setting almost parallel to the horizon in the West. The
overpowering cluster was M7, and the Sagittae-shaped asterism
was the last five stars of the tail of Scorpius, with the rest
of Scorpius below them. According to the Incas, Scorpius was
a monkey hanging by its tail.

I realized much later that there were two reasons that this
all seemed so much more impressive than my familiar view of the
same part of the sky. Most obviously, it was much higher in the
sky than it ever is at my latitude of 42N, although much lower
than in the austral winter, when the center of the Milky Way
lies directly overhead in central Chile. But even more than that,
I was seeing the center of the Milky Way in its proper context,
flanked on the right by the Scutum star cloud which I know well,
but also flanked on the left the Milky Way in southern Scorpius,
in Norma, and in Lupus, which I had never seen before.

This was a theme that was to repeat itself over and over. In some
subconscious way, I had grown to assume that the universe stops
around declination 40S. Intellectually, I was well aware that
there was stuff south of that, but my mental model of the sky
didn't include it. Much later, observing in the morning sky,
I found myself working down the axis of Puppis and on to Carina.
Now I know the northern end of Puppis very well indeed, but Puppis
is a very large constellation, and I had grown accustomed to
thinking of it as a constellation without a southern half.
And here I was not only seeing that mythical southern half of
Puppis, but seeing south of it to Carina, and south of that
to Crux, and then back north again into Centaurus. For the
first time in my life, I really understood at a gut level that
the familiar sky doesn't stop at all, but keeps on going and
comes back again under my feet to form a complete sphere.
That is the most valuable thing that I bring back from my
trip to Chile.

- Tony Flanders