The constellation of Cancer
is the site of an open star cluster called M67. It is one of the
oldest known open clusters and is believed to be over 3 billion
years old. It is also the oldest cluster in the Messier catalog.
This cluster is located about 2,700 light-years from Earth. It
contains around 500 stars, some 200 of which are believed to be
white dwarfs. At magnitude 6.1, it is an easy target for the
binocular observer. Viewing through a telescope will reveal some
of the cluster's fainter stars.