Cassiopeia
What is Cassiopeia?
Constellations· Autumn–winter (N, circumpolar) · five-star W. The northern W. When the Dipper sinks low, Cassiopeia takes over as the guide to Polaris — the two landmarks face each other across the pole.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Cassiopeia is in your sky right now: https://nowsky.org/solar/sky?sel=con:Cassiopeia — location and time set automatically, no login.
Stars of the figure
| Star | Magnitude |
|---|---|
| Schedar | 2.2 |
| Caph | 2.3 |
| Gamma Cassiopeiae | 2.5 |
| Ruchbah | 2.7 |
| Segin | 3.4 |
The 5 brightest of the 6 stars used in the figure (5 lines). Lower magnitude means brighter.
Deep-sky objects near this constellation
Constellation basics
| Season | autumn–winter; circumpolar |
|---|---|
| Shape | five stars in a W |
| How to find | the W opposite the Big Dipper |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Frequently asked
- When can I see Cassiopeia?
- autumn–winter; circumpolar.
- How do I find Cassiopeia?
- the W opposite the Big Dipper.
- What is the brightest star in Cassiopeia?
- Schedar, magnitude 2.2.
- Where is Cassiopeia in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
The middle star of the W, named backwards after an astronaut
The star at the centre of the W, Gamma Cassiopeiae, has no classical name. Its nickname Navi is the middle name of astronaut Gus Grissom, Ivan, spelled backwards; Grissom slipped it into a list of navigation stars as a joke during Apollo training, and after his death in the Apollo 1 fire the name stuck.
It is a variable Be star. Rotating at more than 400 km/s, it sheds gas from its equator into a disk, and as the disk forms and dissolves the star swings between magnitude 1.6 and 3. In 1937 it was briefly the brightest of the five. The W of Cassiopeia is a figure whose balance shifts with the decades, because one of its five points is a living variable.
The constellation in depth
Cassiopeia's five stars draw a crisp W (or M, by season) — one of the easiest catches in the northern sky, sitting on the Milky Way where binoculars sweep up cluster after cluster.
It faces the Big Dipper across Polaris: when one rides low, the other rides high — two year-round signposts to the pole star.
In 1572 Tycho Brahe found a supernova here, shattering Aristotle's unchanging heavens — one of the birthplaces of modern astronomy.
Cassiopeia doubles as a backup key to Polaris: when the Big Dipper dips below the horizon, the open side of the W points the way north. Nearby lies the Perseus Double Cluster, one of the finest binocular sights in the sky — select Cassiopeia in the sky view and sweep around it.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.