Sky & Telescope - May 2019 - 45

Cor Caroli

Under the Stars by Fred Schaaf

Meadow in the Sky
During the month of May, take a moment to marvel at
open clusters, globular clusters, and sparkling stars.

A K IR A FUJII

C

arl Sagan once wrote of the Earth
surrounded by space as "a meadow
in the middle of the sky." I've written in
this column previously about a different
"meadow in the middle of the sky."
The meadow in question is the section of heavens bounded by the main
patterns of the Big Dipper, Boötes,
Virgo, and the hindquarters of Leo. It
hangs overhead on May evenings for
observers at mid-northern latitudes.
It contains the constellations Coma
Berenices and Canes Venatici and the
central region of the Virgo Galaxy Cluster. It's bounded by mostly rather bright
stars but is itself sparse of naked-eye
stars - and superbly rich with fuzzy,
intricate, relatively bright galaxies for
amateur telescopes.
Revisiting the meadow in the
sky. In May, when Earth's ﬁelds (or at
least those at temperate latitudes) are
abloom with countless wildﬂowers, the
meadow overhead is similarly blossoming with dozens, hundreds, thousands
of galaxies. But let's ﬁrst consider a
closer resident of the meadow: the
Coma Star Cluster, technically known
as Melotte 111.
The name of the constellation Coma
Berenices means "Berenice's Hair,"
referring to the locks of the historic
Queen Berenice. It's based on the
naked-eye appearance of the Coma Star
Cluster - in a dark sky, an irregular scattering of stars that looks like
beautifully disheveled hair. The cluster
more anciently marked the tuft at the
end of Leo the Lion's tail. The cluster
consists of a few dozen stars, at least
ﬁve of them brighter than magnitude
5.5 and about a dozen brighter than
6.5. It spills over more than 5° of sky,
so you need a pair of binoculars with a
reasonably wide ﬁeld of view to include

Arcturus

the entire cluster (see S&T:
Apr. 2019, p. 43). The Coma
Star Cluster is, at about 280
light-years distant, the second-closest cluster to Earth,
less than twice as far away
as the Hyades. The magnitude-4.4 star Gamma Comae
Berenices, though appearing
near the northern edge of
the Coma Star Cluster, isn't
a member. The brightest true
member is the magnitude-4.8
star 12 Comae Berenices.
Gamma Comae Berenices is useful for ﬁnding the Coma Star Cluster
in a light-polluted sky, for it lies about
2/3 of the way between 2nd-magnitude
Denebola (Beta Leonis) and the 3rdmagnitude beautiful double star Cor
Caroli (Alpha Canum Venaticorum).
Cor Caroli is essentially right at the
zenith at the time of our all-sky map on
the preceding pages.
The diamond in the meadow. The
line connecting Denebola and Cor Caroli is one of four that forms an asterism
that just about ﬁlls the meadow in the
sky. This asterism is one that's rarely
heard of in recent decades: the Diamond of Virgo. I ﬁrst learned about it
in childhood in a beloved little yellow
book, t he 1954 edition of William Tyler
Olcott's Field Book of the Skies.
The other stars of the Diamond are
the brilliant Arcturus and Spica. And
this diamond is extremely valuable for
locating a variety of deep-sky objects. In
addition to Gamma Comae Berenices
and the Coma Star Cluster, we can ﬁnd
virtually all the Virgo Galaxy Cluster
wedged within the western angle of
the Diamond (not far west of Epsilon
Virginis, also known as Vindemiatrix).
About halfway between Arcturus and

Denebola

Spica

p GEM IN THE SKY The Diamond of Virgo is
an asterism that straddles five constellations:
Virgo, Boötes, Canes Venatici, and Leo, which
contain the anchor stars, with Coma Berenices
in the middle.

Cor Caroli is the isolated but great
globular cluster M3. In addition, about
two-thirds of the way along the line
from Denebola to Arcturus - a line
which bisects the Diamond of Virgo
- there shines the magnitude-4.3 star
Alpha Comae Berenices and, about
1° northeast of it, the 7.7-magnitude
globular cluster M53.
Top of the galaxy to you. Within
half a degree of 31 Comae Berenices
is the North Galactic Pole. This is the
direction perpendicular to the equatorial plane of the Milky Way. When the
galactic pole is virtually overhead, the
band of the Milky Way is hidden along
the horizon. But at least very bright
stars bedeck the sky near the horizon
in different cardinal directions at this
hour: Capella in the northeast, Procyon
in the west, Antares in the southeast,
and Deneb in the northeast.
¢ Contributing Editor FRED SCHAAF
welcomes your letters and comments at
fschaaf@aol.com.
s k y a n d t e l e s c o p e . c o m * M AY 2 0 1 9

45
http://www.skyandtelescope.com
Sky & Telescope - May 2019

Table of Contents for the Digital Edition of Sky & Telescope - May 2019
