This is a large,
beautiful open cluster that is visible as a hazy spot in binoculars.
Walter Scott Houston wrote that "NGC 7789 is one of those rare
objects that is impressive in any size instrument." He
described the appearance in a 4-inch as "a soft glow nearly 1/2o
across, and speckled with tiny, often illusive, individual
stars." The view in larger apertures is even more
stunning. I was impressed with how unusually round and regular
this gathering appeared in my 18-inch and can only nod in agreement
with Scotty's description of his view in a 16-inch, "the whole
field is scattered with diamond dust." William Herschel's
sister Caroline discovered NGC 7789 in 1783.
Unlike the Double
Cluster, this grouping of stars formed together relatively long ago
for an open cluster, although the member stars are still relative
newcomers, only about 2/5 as old as the earth and much, much younger
than the globular clusters (which all formed around 11 billion years
NGC 7789 lies about 3o
from Beta Cas.
The field in a 10-inch at
60x. North is down and east is to the right.