Most beginners probably start with telescopes that they
received as Christmas presents. The timing is fortunate,
because in many ways, early winter is the easiest time to
learn deep-sky astronomy in the North Temperate Zone,
especially from light-polluted locations.
The winter sky is full of bright stars and prominent
constellations, including in particular Orion, which almost
everyone recognizes. That makes it easy to orient oneself,
and to locate deep-sky objects. In addition, most of the
winter Messier objects are bright and easy to see, including
most particularly M42, which many people consider to be the
finest deep-sky object of all.
Unfortunately, there is a natural tendency to start with M1,
which happens to be one of the hardest and least spectacular
of all the winter Messier objects. Beginners who set out
to observe all of the Messier objects starting with M1
often give up before they have even started.
Here are the objects that are at their highest in the evening
sky during the early winter, from RA 3 to RA 6. I have also
included M35, which barely fails to fit in this range of RA,
but forms a natural group with M36/M37/M38.
For a key to this table, see
Key to the Tables.
In addition to the objects described in this chapter, you may
want to observe some of the late-autumn objects, from RA 0 to RA 3.
Many of these have northerly declinations
which make them readily visible from the North Temperate Zone
well into the winter. In particular, M31 and its companions
are always worth a look whenever possible.
If you stay up late enough, you can also easily observe the
late-winter objects, from RA 6 to RA 9, and even the magnificent
galaxy pair M81/M82 which is nearly at RA 10.
M45, the Pleiades
M45 is the first of the winter Messier objects to rise as
seen from the North Temperate Zone, and it is a wonderful
introduction to the Messier objects, especially for people
with small telescopes and for urban and suburban observers.
Even the smallest binoculars under the worst conditions
reveal the signature seven stars forming a miniature
dipper. At 25X or so, my 70mm refractor under urban
skies shows all of the important stars of this cluster.
I particularly love the arc of seven faint stars
stretching from Alcyone (eta Tauri), the bright
central star, down to the mag 5.4 star at the south
edge of the cluster, and the lovely tight triangle
of stars just west of Alcyone. Also worthy of mention
is the lovely wide double star Burnham 536 in the
center of the bowl, with two mag 8 components separated
Extra aperture or darker skies do little to improve the
appearance of the cluster; in fact, most large telescopes
cannot deliver a wide enough field to frame the cluster
well. M45 looks best in a field at least two degrees wide.
Under dark skies, some people can see faint nebulosity
around some of the stars of the Pleiades, but there is
no hope of seeing this under urban or suburban skies.
M42 and M43, the Orion Nebula
M42, the Great Nebula in Orion, is by far the brightest
nebulous object visible from most of the North Temperate
Zone; its only serious rival is NGC 3372, the Eta Carina
Nebula, which is never visible north of latitude 30N.
M42 is visible even in the smallest instruments under the
worst conditions, but it is an object that responds very
well to aperture. It is charming in my 70mm scope,
gorgeous in my 178mm scope, breath-taking in my 318mm
scope, and overwhelming in a 500mm scope or larger.
It is also an object that responds well to high
magnification, at least the bright central region.
M42 is a very large and complex object; you could study
it for a lifetime and still find something new every
time you looked at it. At the core of the nebula is
the Trapezium, Theta 1 Orionis, a magnificent
quadruple star, readily split at 25X or higher.
With a medium-sized telescope (say, 150mm or larger)
at highish power, you may be able to make out one or
two more stars, titled E and F. E and F would be easy
to see in small scopes if they were out on their own,
but they tend to be overwhelmed by the glow from nearby
A and C. Their visibility depends primarily on steady
seeing; bright skies are only a minor obstacle.
The area right around the Trapezium is called the
Huyghenian region, after the great Dutch astronomer
Christiaan Huyghens who gave the first detailed
description of it. This area is intensely bright,
and is barely scathed by light pollution. It is
quite small, only a tiny part of the whole nebula,
and is best viewed at high magnifications, as much
as 1X per mm of aperture or higher. Protruding
far into the Huyghenian region is the dark nebula
sometimes called the Fish Mouth. The line of three
bright stars south of the Fish Mouth includes the
components of the star Theta 2 Orionis.
M43 is actually part of M42, separated from the main
nebula by a dark foreground cloud which is evident in
long-exposure photographs. Visually, it appears as
a vague, nearly circular cloud about 3' in diameter
around a brightish star 8' NNE of the Trapezium.
This is an attractive nebula through large instruments
under dark skies, but it suffers badly from light
pollution. It is fairly difficult in my 70mm refractor
under urban skies, but gets easier with larger apertures
and darker skies.
Stretching out from the Huyghenian region are two
great arcs sometimes called the Bat Wings. The southern
Bat Wing is particularly bright, being faintly visible
in my 178mm scope under urban skies at around 60X,
or in my 70mm scope under suburban skies at similar
magnifications. Under very dark skies, the Bat Wings
curve around and meet again half a degree S of the
Trapezium, but there is no hope of seeing this from
the city or suburbs.
I find narrow-band filters somewhat useful on the outer
sections of M42, but I prefer the Huyghenian region
unfiltered at high powers.
M78 is bright for a diffuse nebula, but it is several orders
of magnitude fainter and more difficult than M42. It is quite
hard to see in urban skies, especially in smaller instruments,
but under suburban skies it is visible although extremely hard
in my 7x35 binoculars, and fairly obvious in my 70mm scope.
The nebula is slightly elliptical, roughly 3' by 4'. Look for
the central star or pair of stars, which give the nebula much
of its charm. If you can see M78, you also have a good chance
of seeing NGC 2071 20' NNE of M78. NGC 2071 is smaller than
M78, but otherwise very similar.
Unlike many faint objects, this one seems to show best at
lowish powers, about 40X in my 70mm scope and 60X in my 178mm
scope; the nebulosity tends to fade out at higher powers.
But one of my notes says that at 120X in my 178mm scope,
a new much smaller nebulosity appeared right around the two
central stars, although the main nebulosity had disappeared.
M79 is one of the lesser Messier globulars, quite hard to
resolve in medium-sized scopes even under dark skies.
However, it is bright and highly concentrated, and fairly
easy to see even in small instruments despite the fact that
it never rises high above the horizon at my latitude of 42N.
It shows best at moderately high powers, around 50X in my
70mm scope or 80X in my 178mm scope. At lower powers, it
may look like a fuzzy star.
Under suburban skies, I see a faint halo about 3' across
around a brilliant 1' core. Under urban skies, only the
bright core may be visible.
M1 is very easy to locate off the moderately bright star
Zeta Tauri, but it can be fairly hard to see under bright
skies. It is fairly similar to M78, but perhaps a little
bigger, brighter, and easier to see.
This object is rather attractive in large telescopes under
dark skies, but is lackluster in small instruments and/or
under significant light pollution. Its interest lies in
the fact that it inspired Messier to compile his catalog,
and in the nature of the object. It is the remnant of
a supernova that was observed by Chinese astronomers in
1054, one of the few supernovas to have exploded in our
own galaxy in historic times.
Like M78, M1 shows best at lowish powers, around 40X-50X
both in my 70mm scope and in my 178mm scope. It requires
averted vision through the small scope in the city, but is
fairly easy to see in the larger scope in all conditions.
It is a somewhat blocky patch of light, about 3' by 5',
with fairly distinct edges. The SE quadrant is somewhat
fainter than the rest of the object.
M36, M37, and M38
The three open clusters in Auriga are rather similar to each
other in size and total brightness, yet each is quite different
from the others.
M36 is the most prominent through small instruments; it is
small and bright, consisting of half a dozen mag 9 stars,
another half dozen mag 10 stars, and a modest coterie of
fainter stars. Through my 7x35 binoculars, all of the stars
merge to form a very small but fairly bright and prominent
patch of light. The mag 9 stars stand out well in my 70mm
scope at low and medium powers, and it is apparent that they
are much more densely clustered than the mag 9 stars in the
background. My 178mm scope brings out the faint background
stars much more strongly. This tends to camouflage the
bright stars of the cluster somewhat, making the cluster a
little less prominent. M36 stands out best at fairly low power,
but it show well at 100X or even higher. The cluster's high
surface brightness makes it fairly resistant to light pollution.
Note the lovely double star Struve 737 slightly SE of the center,
with mag 9.1 and 9.4 components separated by 11". Struve 737 is
slightly difficult to split in my 70mm scope under urban skies.
M37 has roughly the same total brightness as M36 but has twice
the diameter, giving it much lower surface brightness and making
it harder to see under heavy light pollution. Nonetheless, it
stands out reasonably well in my 7x35 binoculars from the city,
forming a fairly large, subtle, but attractive cloud of light.
Right in the center of M37 is a prominent mag 9.2 star,
surrounded by a large number of fairly faint stars, very
densely packed, and all within a fairly narrow range of
brightness. In small scopes and at low magnifications,
these stars tend to merge into an unresolved nebulosity,
especially under heavy light pollution. At higher powers,
numerous stars become intermittently visible with averted
vision, a very lovely effect. In my 178mm scope, many stars
are immediately evident even at low power, making the cluster
very attractive and absolutely unmistakable. The cluster
shows best at the highest power that frames it well, probably
around 80X or 100X in an eyepiece with a 50-degree apparent
field of view. At least 100 stars are visible in my 178mm
scope at 100X under suburban skies.
M38 is as large as M37 but significantly fainter, giving it
fairly low surface brightness and making it by far the hardest
of the three clusters to detect under heavy light pollution.
In my 7x35 binoculars from the city, it is a very vague smear
of light, just slightly brighter than the background.
M38 contains about 20 stars from mag 9.9 to mag 10.9, more
tightly clustered than similar stars in the background, but
not dramatically so. Most of the brighter stars lie on two
wavy lines crossing in the center, reminding me of the Greek
letter chi. There is also a stubby projection from the
center, making the cluster look a little like a starfish
with one arm partially amputated. Under urban skies,
most of the brighter stars are visible but not dramatic
through my 70mm scope, making the cluster rather unconvincing.
It improves under suburban skies. My 178mm scope shows all
of the brighter stars immediately, and in darker skies or at
higher powers, it also reveals another 20 or 30 fainter stars
which help to flesh the cluster out. Because the cluster is
rather vague, it needs a rather wide border to frame it well,
best in a field of view around 1 degree.
In good skies, with a 150mm scope or larger, you may be
able to pick out the small, faint cluster NGC 1907 just
half a degree S of M38. It is not particularly interesting
in its own right, but it forms a nice contrast with M38.
Although M38 is the hardest cluster to detect, it is very
easy to locate, being almost exactly half way between
iota and theta Aurigae. M36 and M37 symmetrically straddle
a line connecting theta Aurigae and beta Tauri (El Nath),
slightly closer to theta Aurigae. If the clusters cannot
be found by the point-and-hope method, they are rather
arduous star-hops from the nearest naked-eye stars.
The appearance of the three clusters reflects their
underlying nature. M36 is a young, fairly sparse cluster,
very much like M45, but about ten times more distant,
making it appear ten times smaller and one hundred times
fainter. The brightest stars are still on the main
sequence, burning hydrogen, and showing white or blue.
M37 is much richer and much older. All of its very bright
stars have already burned out, leaving the remainder fairly
narrowly clustered in brightness. The brightest of the
remaining stars are all red or yellow giants, near the
end of their lives. The reddish color of the bright
central star is particularly obvious in my 178mm scope.
Stars in a cluster interact much like the molecules in a
fluid. The stars do not actually bounce off each other,
but when two stars come close, their gravitational
interaction has much the same effect. As in a fluid, the
net effect is that the heaviest stars eventually settle
to the bottom (the center of the cluster), while the
lightest stars "evaporate", or escape from the cluster.
The heaviest stars are also the brightest, and the ones
that reach red-giant stage the soonest; therefore, it is
very common to find one or two bright red stars near the
center of a mature cluster.
M38 is intermediate between M36 and M37; about half of the
brightest stars are on the main sequence, shining blue or
white, and the other half are red or yellow giants.
M38 is dominated by a small number of stars considerably
brighter than the rest, but not so few nor so bright as
the bright stars of M36.
M35 has something for everyone. Its brightest stars are
even brighter than those of M36; a few are mag 8 or
brighter, making them readily resolvable by my 7x35
binoculars under urban skies. But M35 also has plenty
of stars in every brightness range below that, down to
a cloud of mag 12 stars that rivals M37's.
M35 is about half the distance of the clusters in Auriga
(2000 light years as opposed to 4000), which accounts for
the brightness of its stars and for its enormous apparent
size. The brightest stars of M35 are split roughly evenly
between the main sequence and the red giant branch; perhaps
this is what M37 looked like before its brightest stars
M35 is faintly visible to the naked eye under the best
suburban skies, and fairly easy under dark skies. It is
also very easy to locate off the right-hand "foot" of
Gemini, the star eta Geminorum, which is visible in all
but the worst skies.
Nonetheless, M35 does not stand out as well as M36 in
small instruments under heavy light pollution. Much of
its brightness is contained in the half-dozen brightest
stars, but those stars are spread out over a large area
instead of forming a tight, distinctive pattern like that
of M36. The fainter stars merge into a nebulous background
that stands out well in dark skies, but its surface brightness
is too low to be seen easily from the city.
In my 70mm scope, M35 shows best at around 60X. Under urban
skies, this brings out just enough stars to make the cluster
look like a cluster. M35 is spectacular in my 178mm scope
even under the worst conditions, but it is a struggle to
find a magnification low enough to frame the cluster well
yet high enough to bring out its faint stars and resolve
its intricate detail. 80X seems optimal with a standard
Plossl eyepiece, but higher powers could be used if the
eyepiece has a wider apparent field of view.
In good skies, you might take a look for nearby NGC 2158
about 20' SW of M35's edge. It shows quite easily even in
small instruments under dark skies, but suffers badly from
light pollution. Through a large telescope, NGC 2158 is one of the
prettiest of all open clusters, even richer than M35.
However, it is also much farther from us than M35,
making it quite hard to resolve in modest telescopes.