NGC 7209 -- Open Cluster in Lacerta
A Star Cluster in the Mediterranean Newt
Some people got upset when Pluto was demoted to a dwarf planet. Not me, I am easy
going. But as a biologist to call the constellation Lacerta a Lizard is fighting words.
Johann Hevelius in 1687 named the constellation after a spotted Mediterranean newt
which is a Salamander (Amphibian) and not a Lizard (Reptile). Each time I venture into
this section of the night sky, it is all that I can do to keep from tearing-down my telescope
and go indoors, at least until I can regain some degree of composure.
On the other hand, Lacerta does contain a couple nice open clusters which are worth a
visit – regardless of the ill-named constellation. NGC 7209 really helps -- it is a pretty
arrangement of stars with little or no central concentration. It is best viewed at low power.
Located within the cluster is the star SS Lacertae. This was an eclipsing binary with a
14.4-day period up to the middle of the twentieth century; then it stopped!! SS Lacertae
turned out to be a three-star system and the orbital dynamics of the system moved the tilt
of the orbit of the eclipsing binary pair just enough that the stars no longer were eclipsing
each other as seen from Earth. But the non-eclipsing status is expected only to last until
the twenty-third century. Then once again SS Lacertae will become an eclipsing binary
star. I hope that by then astronomers will have corrected their biological error with the
constellation’s name.
going. But as a biologist to call the constellation Lacerta a Lizard is fighting words.
Johann Hevelius in 1687 named the constellation after a spotted Mediterranean newt
which is a Salamander (Amphibian) and not a Lizard (Reptile). Each time I venture into
this section of the night sky, it is all that I can do to keep from tearing-down my telescope
and go indoors, at least until I can regain some degree of composure.
On the other hand, Lacerta does contain a couple nice open clusters which are worth a
visit – regardless of the ill-named constellation. NGC 7209 really helps -- it is a pretty
arrangement of stars with little or no central concentration. It is best viewed at low power.
Located within the cluster is the star SS Lacertae. This was an eclipsing binary with a
14.4-day period up to the middle of the twentieth century; then it stopped!! SS Lacertae
turned out to be a three-star system and the orbital dynamics of the system moved the tilt
of the orbit of the eclipsing binary pair just enough that the stars no longer were eclipsing
each other as seen from Earth. But the non-eclipsing status is expected only to last until
the twenty-third century. Then once again SS Lacertae will become an eclipsing binary
star. I hope that by then astronomers will have corrected their biological error with the
constellation’s name.