46 ASTRONOMY • JANUARY 2022
65 The Blackeye
Galaxy
Extragalactic pugilist M64, the Blackeye Galaxy
in Coma Berenices, sports a massive shiner of
dust that lies asymmetrically across the galaxy’s
prominent bulge. Apparently, M64 met another
galaxy over a billion years ago and did not so
much battle it as assimilate it. Nevertheless,
that feisty dwarf system caused significant
turbulence in M64: The stars and gas in M64’s
inner disk rotate in the opposite direction as its
outer regions.
Compression during the merger likely
ignited bouts of regional star formation in the
galaxy’s bulge, where youthful stars contribute
a blue tint. This contrasts nicely with the red tint
found at the galaxy’s core, which is rich with
older stars. Cataloged distances to M64 vary,
but recent estimates put it at between 14 million
and 24 million light-years away.
English astronomer Edward Pigott discov-
ered M64 on March 23, 1779. Twelve days
later, German astronomer Johann Elert Bode
independently sighted it as a “small nebulous
star.” Pigott’s observation, however, was not
made public until it was read before the Royal
Society of London in 1781. Messier was unaware
of this find when he prepared his final catalog.
Consequently, Pigott’s discovery remained
in the shadows until 1907, when French
astronomer Guillame Bigourdan linked Pigott’s
reported position of the “nebula” to M64.
To find this intriguing galaxy, look just
1° northeast of 5th-magnitude 35 Comae
Berenices. Under a dark sky, the magnitude-8.5
galaxy appears as a tiny puff of light through
10x50 binoculars. Small telescopes will show its
smooth, oval disk (10') punctuated by a bright
core of light. The disk also has a milky sheen
and a blue-white color.
The galaxy takes magnification well. High
power is required to see its black eye, which
skilled observers have glimpsed through aper-
tures as small as 2.4 inches. Moderate-sized
telescopes and high magnification, however,
are generally required to show this dust
patch well. Look for a subtle absence of light,
rather than an intense darkness. At 240x, John
Herschel called it a “vacuity below the nucleus.”
(Curiously, at 320x, he thought the nucleus
resembled a double star.) Seeing the galaxy’s
pinwheel arms requires larger apertures, as
well. — S.J.O.66 Alpha and Proxima Centauri
The third-brightest star in the sky, Alpha (α) Centauri, gleams in the southern constellation
Centaurus. Since it is positioned at a declination of almost –61°, only stargazers located south of
latitude 29° have any hope of seeing it. But those who can will never forget their first glimpse.
Proximity is the main reason this star, also known as Rigel Kentaurus, appears so bright in our sky.
At just 4.37 light-years away, it’s our nearest stellar neighbor.
When we look at Alpha Centauri, we're not seeing a single star, but a triple-sun system. The big-
gest and brightest member of this stellar family, shining at magnitude 0, is Alpha Centauri A, a type G
main sequence star like the Sun. Alpha Centauri B, an orange type K star, glows at magnitude 1.3 and
orbits A once every 79.9 years. Their apparent separation varies from just 2" to 22" throughout each
orbit. The stars are now slowly creeping closer to one another as seen from Earth, having passed
their maximum separation, or apastron, in 1995. Their next closest approach, or periastron, is in 2035.
At 4.24 light-years distant, the third star in the system, Proxima Centauri, is slightly closer to us
than the other two. But being a tiny red dwarf star, Proxima is far fainter than our naked eyes can
detect. It shines at only magnitude 10.4, appearing as a dim red speck about 2° southwest of the
brighter Alpha pair.
However, in 2016, Proxima outshone
both Alphas in the news when astronomers
announced the discovery of an extrasolar
planet orbiting the petite sun. Dubbed
Proxima Centauri b, it's about 25 percent
more massive than Earth. And even though
its orbit is equivalent to about one-eighth
the distance between Mercury and the
Sun, it resides within Proxima’s habitable
zone, where liquid water could exist on the
planet’s surface. Still, odds of life spawning
there are considered slim. Proxima some-
times produces massive flares, bathing the
planet’s surface in lethal levels of radiation.
A second planet, Proxima Centauri c, was
discovered four years later. It is about seven
times the mass of Earth and orbits outside
Proxima’s habitable zone. — P. H.
CHRIS SCHURALAN DYER WAGNER AMARAL