94 The Beehive
Cluster
M44 is one of the heavens’ largest,
brightest, and nearest open star clusters
— a wonder accessible to stargazers of
all skill levels. This attractive swarm of
stars is visible to the unaided eye as a
nebulous patch spread across 1° of sky,
appearing like the elongated head of a
comet passing through the heart of Cancer
the Crab. Known throughout antiquity,
3rd-magnitude M44 outshines all the stars
of Cancer by a full magnitude, making
Cancer the only constellation in which a
deep-sky object is more conspicuous than
the constellation itself.
Ptolemy wrote that this mystifying mist
was the “center of the cloud-shaped con-
volutions in the breast [of the Crab], called
Praesepe.” One of the earliest monikers for
the cluster, Praesepe is derived from the
Latin word presepio, which means “manger,”
referring to the straw-filled manger of the
infant Christ. If M44 represents the straw,
it is guarded by the two aselli (Latin for
“donkeys”) — the 5th-magnitude Gamma (γ)
and 4th-magnitude Delta (δ) Cancri.
Galileo first resolved M44 into a mass
of 40 stars with his primitive telescope
— a view similar to that through today’s
handheld binoculars. But the grouping’s
more popular name, the Beehive Cluster,
comes to us from the English observer
John Herschel, who, in his 1833 Treatise
on Astronomy, tells us that the Praesepe
resolves into a swarm of stars with an “ordi-
nary night glass.” Thus, properly speaking,
the Praesepe refers to the naked-eye view,
while the Beehive refers to the telescopic
view — which, through even the smallest
of telescopes, reveals a swarm of nervous
starlight.
M44, which is located some 515 light-
years away, is a collection of at least 1,000
stars. Most are too dim to see; about
200 range in brightness from 6th to 14th
magnitude, 80 of which are brighter than
magnitude 10. Keen-eyed observers have
resolved several of the brightest stars with
their unaided eyes. The 600-million-year-
old cluster stretches across 15 light-years
of space. — S.J.O.
95 The Ring
Nebula
The Ring Nebula (M57) was first discovered in
the winter of 1779. But by whom? Some claim
it was French astronomer Antoine Darquier
de Pellepoix, while others insist it was Charles
Messier. However, most historians now seem to
agree it was indeed Messier who found it first.
The Ring Nebula is the sky’s most famous
example of a planetary nebula. Messier
described it as “very dull, but perfectly outlined;
as large as Jupiter and looks like a fading
planet.” This analogy to a planet led William
Herschel to coin the term — which, even though
it is scientifically inaccurate, we still use today.
Interestingly, while many early telescopic
observers referred to objects that we now know
are star clusters as “nebulae,” they consistently
thought the opposite of M57. The Ring Nebula
was often misclassified as a star cluster. It was
not until 1864, when English astronomer William
Huggins conducted pioneering spectroscopic
studies of M57, that its true nature came to light.
Appearing as a dim star along the south side
of Lyra the Lyre’s rectangular frame, the Ring can
still be spotted through binoculars and finder
scopes. Its famous doughnut shape becomes
clear at magnifications between about 100x
and 150x. Although the Ring appears smooth
and evenly bright through smaller instruments,
8-inch and larger scopes will reveal some bright
and dark irregular patches around its surface.
The Ring Nebula resides about 2,000 light-
years from Earth and stretches about 1 light-year
across. For years, astronomers believed itwas cylindrical, with its long axis aimed toward
Earth. But we now know it’s much more complex.
An outer shell of nitrogen appears red in deep
images, while an inner shell of hotter oxygen takes
on a green hue. The blue interior (due to copious
helium) sports a football shape that’s projecting
outward toward us. And in the center of it all is
the white dwarf responsible for the Ring.KASRA KARIMI