The Hexagon's Cap
is visible this evening, if one knows where to look.
(Yes, we're just as surprised as you are to read that sentence.)
That one can observe the
Winter's Hexagon's
northernmost star in late July illustrates two principles: one, that
astronomers should be more careful assigning names to star patterns,
and, two, that the wholly predictable night sky is not without its
surprises. For those who might have forgotten, the Winter Hexagon
is a vast oval-shaped pattern consisting of stars from different
constellations. Starting from the southernmost point, these Winter Hexagon
points are Sirius (Canis Major), Rigel (Orion), Aldebaran (Taurus),
Capella (Auriga), Castor and Pollux (Gemini) and Procyon (Canis Minor.)
Some astronomers also include Betelgeuse (Orion), positioned almost
dead center within the hexagon. Other uncooperative astronomers don't add Betelegeuse as it doesn't contribute to the Hexagon's boundaries.
The Winter Hexagon
While most of the Winter Hexagon is not currently visible in the evening sky, we can still see the Hexagon's "cap"
low in the north. Capella, the northernmost star within the Hexagon, is a "Vegan" star, meaning
that Capella is not circumpolar, but is still visible for at least part of the night every night of the year.
The Winter Hexagon is
conspicuously absent from the evening sky now, but, give us six months,
when we're facing a different part of the galaxy, and one will see this
brilliant stellar conglomeration front and center in the evening sky.
We call it the "Winter Hexagon" because it is easy to see in the winter.
Presently, most of its stars are only now just rising in the pre-dawn
eastern sky. One star, its northernmost member, Capella,* lingers
almost ominously in the northeastern mid evening sky. It is THAT
strange bright star that just hangs above the northern horizon when
everybody's attention is focused on the Summer Triangle, Sagittarius and
the other summer sky adornments. Despite lurking low along the nether
edge, Capella is still easy to spot, as it is the night sky's sixth
brightest star.
Apart from this distinction, Capella is also a "Vegan star," defined as a
star that is visible for at least part of the night every night of the
year. Pronounced "Vay gan," Vegan stars are hybrids: not high enough
to be circumpolars -stars that never set- but high enough to make an
appearance on stage each night. These stars are named for Vega, the
brightest star in the Summer Triangle. It, too, is visible for at
least part of the night each year.**
It is easy to forget that the Universe is a show on a half shell: that
the center stage acts in the south comprise only a small part of the
entire ensemble. If you're pining for
winter
and yearn for its return, we'll cheerfully inform you that we can do
nothing to hasten its arrival. Instead, we can point you to the secret
northern sky corner, where Capella, the Winter Hexagon's highest star, meanders quietly along, waiting for the deep winter chill to return.
Hmm... can't wait.
*Remembering that Capella sits atop the
Winter Hexagon is easy: just think of it as the Winter Hexagon's "cap."
**Vega and Deneb, the Summer Triangle's other northern star, are both
Vegan stars. For instance, one can find them both peeking above the
northern horizon on an early evening in February. They set by mid
evening, only to rise again well after midnight. They are the stars
that console the summer lovers as they languish through winter.