Sky and Telescope - May 2016 - 45

OBSERVING

Northern Hemisphere's Sky

Fred Schaaf welcomes your
comments at fschaaf@aol.com.

Fred Schaaf

The Tale of All Tails
From comets to constellations, May is the month for celestial tails.
Comet Halley, 1986

AKIRA FUJII

May is a month for tails - and tales about them - in
the sky. I'll start with comet tails, but our main topic this
month is the many constellation tails that appear on the
May meridian.
Did you see a long tail on Halley's Comet 30
springs ago? In early May, 30 and 33 years ago, I
glimpsed two of the most amazing long comet tails of
my life. One belonged to the closest comet to pass Earth
in more than 200 years, Comet IRAS-Araki-Alcock. The
other belonged to the most famous of all comets, Halley. I have a request: if you saw or photographed a great
length of Halley's tail in late April or early May 1986,
please share your tale about it by contacting me.
Seven tails on the May meridian. Those 1983 and
1986 comet tails were incredibly rare sights. But every
year, we have the opportunity to observe the starry tails
of the May evening sky. No less than seven tails are
poised right on the sky's meridian at the time of the
all-sky map at the center of this magazine, and two more
are rising. Several of these tails oﬀer very special sights
for amateur astronomers.
Tails of the bears, hunting dogs, and dragon. The
most prominent tail on the May meridian is the long one
of Ursa Major, the Great Bear. Bears don't have long tails.
How Ursa Major - and Ursa Minor - got one remains
something of a mystery. One mythic explanation is that
the tails got elongated when the bears were hurled into
the heavens by them.
The tail of Ursa Major - which is also the handle of
the Big Dipper, Great Plough, and Celestial Wagon (see
page 24) - serves as the "arc to Arcturus."
But the tail of Ursa Major is a fascinating sight in
itself. Test on any given night whether your naked eyes
can see the faint star Alcor perched near the bright star
that forms the bend or crook in the Great Bear's tail -
Mizar, itself a ﬁne double star in almost any telescope.
To one side of the Great Bear's tail is the sometimes
visually elusive M101, one of the truly classic face-on spiral galaxies. To the other side (south) of the Ursa Major
tail is another such galaxy, this one very prominent
indeed. I'm referring to M51, which is actually not in the
bounds of Ursa Major, but rather in mostly faint Canes
Venatici the Hunting Dogs - a pair of constellational
creatures with tails (see page 43).
The May meridian also has the tail of Ursa Minor

standing vertically beside it. But there is a less frequently
noticed tail that sticks right between the two Bears, or
Dippers. It's the tail of Draco, the Dragon. Most of the
famous stars and other deep-sky objects of Draco are in
the dragon's head and coils. But between Mizar, at the
middle of the Great Bear's tail, and the "Guardians of the
Pole," the two rather bright stars in the Little Bear's body
(Little Dipper's bowl), shines Alpha (α) Draconis, the
star also known as Thuban. Thuban was the North Star
of the earliest days of Egyptian civilization - a mere 4½
thousand years ago.
Many more tails for May evenings. Before the big,
loose naked-eye Coma Star Cluster was turned into the
hair of Queen Berenices in later Classical times, the
cluster represented the tuft of the tail of Leo. It's right
on the meridian this time of year. So, more or less, is the
tail of long, long Hydra, the Sea-Serpent.
And there are two newly arrived tails in this month's
sky. The front half of Scorpius, featuring Antares (and,
this May, blazing Mars!) is all that's up at our map time.
But look what's just risen in the northeast and east:
Cygnus, the Swan, with its ﬁrst-magnitude tail star,
Deneb (the name Deneb even means "tail"), and Serpens
Cauda, the tail section of the expansive two-part constellation Serpens, the Serpent. ✦
Sk yandTelescope.com May 2016

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Sky and Telescope - May 2016

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