- Hercules is a constellation named after Hercules, the Roman mythological hero adapted from the Greek hero Heracles. Hercules was one of the 48 constellations listed by the second-century astronomer Ptolemy, and it remains one of the 88 modern constellations today. It is the fifth-largest of the modern constellations and is the largest of the 50 which have no stars brighter than apparent magnitude +2.5.
- How to find and observe Eta Cas (TOTS#2) (eyesonthesky.com)
Eta Cas is a double star within our own Milky Way galaxy. It is quite close to Earth, at just 19.4 light years, so the photons reaching your eye from the star tonight are under 20 years old. What makes Eta Cassiopeiae so interesting is that the primary star is a G-class star much like our Sun. Our Sun would look similar from Eta Cas if we were peering back it it from there. It also has 97% of the mass, and is 101% of the radius of our Sun. It is much like a twin of our host star in many respects, though it is likely about a billion years older. Here is how to locate it.
