- Well, we've hit the horizon and run out of Milky Way so we'll hang a left
and head south along the horizon, which brings us to the Zodiac constellation
Capricornus. This is a faint constellation, you have to look hard to see it.
In rough terms it's an upside-down triangle, curved a little bit so it starts
to resemble a big smile. {Trace out Capricornus} Unfortunately it isn't called
Capricornus the Big Smile, it's called Capricornus the Goat. Well actually, a
goat with a fish tail. See it?
Nah, me neither. But here's what you can see, if you look hard at the
brightest star of the (not too bright) constellation, at the upper right
(Northwest) corner, a Capricorni, also called Giedi
Prime. For you Dune fans, yes, that's where the bad guys live. But look at
it... is that one star or two? What do you think? That's right, it's two --
hey hey hey, that's cheating, looking in the binoculars! They aren't related
to each other, the dimmer one to the right is about five times farther away
than the brighter one to the left, but it turns out each one is itself a true
double. Ah - so no wonder it's the brightest star in Capricornus - it's four
stars.
- I called Capricornus a Zodiac constellation. What is a
"Zodiac" constellation? (I have been surprised to
discover that few, if any, kids can answer this question.)
As the earth goes around the sun, this motion means that every day we look
back at the sun in a slightly different direction, with different stars behind
it. The sun appears to move through the constellations. Theoretically there
are twelve constellations through which the sun moves, one per month, and
these are the Zodiac constellations. In reality there is a 13th
constellation through which the sun passes (technically, at least) and it gets
no credit for being in the Zodiac - Ophiuchus.
- Now directly above Capricornus, and below the Great Square of Pegasus, we
have the next of the Zodiac constellations, Aquarius. Yes, this is THE
Aquarius, as in the Age of Aquarius in the song. Aquarius is just as faint as
Capricornus, and it's an odd constellation that wanders around the sky. As a
result, it's best to find it piece by piece.
Aquarius is a water carrier, pouring his pitcher of water into a standing
urn. We start with the figure of Aquarius, which is a straight line, which
begins just above Capricornus {I'm pointing to e} and
angles up at to the left {drawing a line to b then to
a}. His water jar is the "Y" shaped figure of stars
next to a Aquarii, and is probably the easiest part
of the constellation to identify. The urn is then right below it {trace out
the urn}, complete with little feet holding it up.
- Just below Aquarius you can see a lone bright star in the sky, a first
magnitude star by the name of Fomalhaut (pronounced like "foam a lot"). This
is the eye of the Southern Fish, Piscis Austrinus. Just below Fomalhaut is a
pair of stars forming the mouth of the fish, and the remaining stars trace out
the body of the fish quite nicely {Trace out Piscis Austrinus} He even has a
little fishy-fin. Fomalhaut is easily recognized since it is the one bright
star to the south in the fall. It is also part of a constellation that looks
just like what it is supposed to be.
- Piscis Austrinus is not a Zodiac constellation, but the next Zodiac
constellation is also a fish, in fact it's two fishes, known as Pisces. This
is another really faint one, and we will start on it with a faint but
distinctive asterism known as the circlet, just below the Great Square of
Pegasus, a little circle (or more accurately, an ellipse) of stars that
represent one of the fishes. The rest is tricky, as it represents a cord that
ties this fish to the second. The cord forms a "V" shape, with our circlet at
one tip of the V and the other fish, represented by just three stars, at the
other tip. {Trace out Pisces}
Two stars of note in Pisces are z (zeta) Piscium,
and another star with the peculiar designation of "TX". To appreciate z we will get it in the telescope, where you can see it is
a very nice binary star - a white star with a fainter yellow companion to the
northeast. Meanwhile TX, the leftmost (eastern-most) star of the circlet, is
just a red star -- a really, really red star. This star is a "carbon star" -
it has been red giant a long time, burning the helium ash from the burned-up
hydrogen and producing carbon. That means this is a very old, and very red,
red giant star.
- If you're going for the Astronomy merit badge you need four Zodiac
constellations and it just so happens you're in luck... we've got one more,
this time going west from Taurus. So this is on the sun's path before
it reaches Taurus; just to the west of the Pleiades you find the constellation
Aries the Ram. The easiest part of the constellation to spot is a set of three
bright stars forming a bent line or a very flat triangle. {Point out the
central stars in Aries.} Most star charts only show these three stars.
However, if you follow the line of the whole constellation you get a much
better sense of the ram's horns. {Trace out the full constellation.}
- The little bitty triangle buzzing around to the left of the bright central
stars of Aries used to be a constellation of its own, called the Northern Fly.
{Point out the Northern Fly.} Mercifully the fly was gassed and now those
stars are officially part of Aries. (There is a Southern Fly - since the
demise of Northern Fly the Southern Fly is just the Fly - near the Southern
Cross close to the South Pole. We can't see it.)
- Just to the north of Aries you might notice a distinct, narrow triangle of
stars, which happens to be another constellation whose name is, surprisingly
enough, Triangulum. {Trace out Triangulum}
- Aside from being a neat looking constellation, Triangulum is the home of
another galaxy, M33. This galaxy is just a little farther from us than the
Andromeda galaxy, about 2.4 million light years away, and belongs to our group
of galaxies - astronomers refer to this as the "Local Group".
M33 has a reputation for being tough to see and we need a clear, dark sky
to really be able to see it. {Point out M33's location} It is so big, faint,
and spread out, that it is actually easier to see in binoculars (if we can see
it at all) than in a telescope. On a very dark night you might even be able to
see it with your eyes alone, by looking just to one side of it (averted
vision).
- The three bright stars of Aries are a (alpha),
b (beta), and g (gamma). If
we get the telescope on g, you can see that it is
also a binary, a close pair of clear white stars. If you don't want to bother
with the telescope you can spot another double with the binoculars -- mid-way
and slightly above the line between a and b is l Arietis, a bright yellow
star with a faint yellow companion, just above it. You can spot the faint twin
with 10x50 binoculars - if you hold them rock steady. Both of these double
stars, g and l, are true
binary systems -- twin stars that were formed together and are now orbiting
one another.
Back to the
Milky Way 
Go to Autumn
Index 
On to the Legend
of Andromeda