Stars · Star in Cetus
Star
Mira
“The wonderful”: the first star known to vary. Every 332 days it swells from invisible to easily visible and back.
- Constellation
- Cetus
- Designation
- ο Ceti
- Apparent magnitude
- 6.47 · 8528th brightest star in the night sky
- Spectral class
- M5e-M9e
- Distance
- 299 light-years
- Position (J2000)
- RA 2h 19m · Dec −2° 59′
A red star, around 3,100 K, like Betelgeuse and Antares. Right at the edge of naked-eye visibility. The light you are seeing left around 1727.
Discovery
In 1596 David Fabricius saw it fade and vanish, and in 1638 Johannes Holwarda found it came back on a schedule. It overturned the belief that the stars are unchanging.
Science
Mira is a pulsing red giant trailing a tail of gas 13 light-years long — discovered in ultraviolet in 2007.