Cassiopeia Constellation
Cassiopeia (The Queen)
Cassiopeia is a prominent constellation in the northern sky, easily recognizable by its distinctive "W" or "M" shape, formed by five bright stars. It represents the mythological queen Cassiopeia, known for her legendary beauty and vanity. The constellation is visible year-round in the Northern Hemisphere and is located near the North Star, Polaris.
Key Features
- Bright Stars: The stars that form Cassiopeia's unique shape are:
- Deep-Sky Objects: Cassiopeia is home to several notable astronomical objects:
- Messier 52 (M52): A rich open star cluster located about 5,000 light-years away.
- NGC 281 (Pacman Nebula): A bright emission nebula resembling the video game character Pac-Man.
- Heart and Soul Nebulae: Large emission nebulae located near the border of Cassiopeia and Perseus.
- NGC 7789: An open cluster also known as "Caroline’s Rose," located about 8,000 light-years away.
Mythological Background
In Greek mythology, Cassiopeia was the queen of Ethiopia, wife of King Cepheus, and mother of Andromeda. She was known for her vanity, boasting that her beauty surpassed that of the sea nymphs, the Nereids. This angered Poseidon, the god of the sea, who sent a sea monster to devastate their kingdom. To appease Poseidon, Andromeda was chained to a rock as a sacrifice but was ultimately rescued by Perseus.
As punishment for her arrogance, Cassiopeia was placed in the sky, where she circles the celestial pole. At certain times of the year, she appears upside down, a reminder of her humiliation.
Cultural Significance
Cassiopeia has been a key constellation for navigation due to its proximity to the North Star, Polaris. Its distinctive "W" shape makes it one of the easiest constellations to identify in the night sky. It is often used as a reference point to locate other constellations and deep-sky objects.
The constellation’s mythological associations with beauty, vanity, and redemption have made it a popular subject in art and literature. Its rich field of stars and nebulae also makes it a favorite target for amateur astronomers.
Cassiopeia Rise and Set Timetable
| Time | Elevation | |
| Cassiopeia is always above the horizon | ||
| Sunset | 21:02 | 9° |
| Civil sunset | 21:36 | 10° |
| Astrosession begin | 22:18 | 12° |
| Cassiopeia is always above the horizon | ||
| Moon Rise, 45.2% illuminated | 01:45 | 29° |
| Astrosession end | 04:48 | 51° |
| Civil sunrise | 05:30 | 57° |
| Sunrise | 06:04 | 61° |
| Cassiopeia Transit | 08:24 | 71° |
| Moon Set | 14:38 | 32° |
Track Cassiopeia Position Throughout the Night
← Thu, 19 June 2025 →
| Time | |
| Altitude | |
| Azimuth |
Annual motion of Cassiopeia
| Date | Thu, 19 June 2025 |
| Twighlight start | 23:02 |
| Twighlight end | 03:54 |
| Twighlight duration | 5h 52m |
| Rise | Cassiopeia is always up |
| Set | Cassiopeia is always up |
| Elevation at transit | 71° |
| Transit time | 08:24 |
| Equatorial coordinates | RA: 00h 44m 49s", Dec: 59° 07' 01s |
| Magnitude | - |
| Constellation |
The graph is structured with the vertical axis showing the hours of the day, ranging from 12 AM to 12 AM the next day, while the horizontal axis spans each day of the year.
The reddish shaded area indicates the periods when the Cassiopeia is above the horizon, visible to observers. The white line marks the times when the celestial object reaches its highest point in the sky each day, known as the transit.
Acknowledgements
We gratefully acknowledge the International Astronomical Union (IAU) for defining and standardizing the official constellation boundaries, which provide a consistent framework for celestial mapping.
Special thanks to Sky & Telescope Magazine and contributors Roger Sinnott and Rick Fienberg for their collaboration in producing the charts and tables. The constellation patterns, drawn by Alan MacRobert, were influenced by the work of H. A. Rey and thoughtfully adjusted to align with earlier traditions.