All stars do not shine with equal intensity night after night. Even our sun’s energy output may change slightly over time. Some stars change brightness in a rhythmic pattern. Over days or weeks, they brighten to peak intensity, then then dim considerably. Various factors affect how they change.
One such variable star is Mira. It is a pulsating star and brightens about every 330 days. It is from a star that pulses in that time period. At its dimmest, it is nearly invisible to the unaided eye. At its brightest, it is a reasonably bright star, but not among the brightest. The changing brightness easily goes unnoticed.
A note from Robert C. Victor provides recent observations of Mira:
Mira may now be near peak brightness. The “V” of Hyades and Aldebaran (head of Taurus) points directly to 2.5-magnitude Alpha Ceti. In same direction, 7 degrees farther, is 4.1-magnitude Delta Ceti. (Don’t be distracted by 3.5-magnitude Gamma Ceti nearby to Delta’s NNE.) A line from Alpha Ceti to Delta, 7 degrees long, extended 6 degrees beyond Delta, locates Mira. In coming weeks, as Mira begins to fade, Alpha, Gamma, and Delta Ceti will serve as useful comparison stars. For recent reports of Mira’s brightness, go to aavso.org and enter “omi cet” (without the quotation marks) into the empty box, and select recent observations or light curve. Make your own observation first!
You can read Rober Victor’s monthly columns in the Palm Springs, CA news paper.