Observe Mira, the Amazing Star

Frequent Sky & Telescope contributor Alan Whitman (most recently author of Beyond the Familiar Veil) points out that the variable star Mira is at or near its peak brightness. Alan estimates it at magnitude 2.3, and some reports to the AAVSO place it as bright as 2.1. Either way, it's about as bright as it's been in living memory.

Sky chart for Mira
S&T Illustration
The name Mira means amazing or wonderful, and this star certainly qualifies. It's by far the brightest star that routinely varies by a factor of 100 or more in brightness. It's usually 9th magnitude at minimum, barely visible even with binoculars. But right now, it's one of the brightest stars in its sector of the sky.

Mira is particularly easy to locate in late 2011, since it's about 15° south of dazzling Jupiter. Hold out your right hand at arm's length with thumb and little finger outstretched. Put your thumb on Jupiter in the evening sky and tilt your hand clockwise a little; your little finger will be near Mira.

Mira is due to peak around October 1st and remain visible to the unaided eye for the rest of the year, though it should become about one magnitude fainter during each succeeding month. Keep an eye on it; you will be amazed how much the appearance of its constellation (Cetus) depends on how bright Mira is.

2-color closeup
In this two-color closeup by GALEX, far ultraviolet is shown as blue and nearer ultraviolet as red. Mira appears to be emitting two swirly streamers of stuff, which spread out to form a comet-like head and, eventually, tail. Note the detached bow shock of far-ultraviolet gas just in front of the head, to the right.
http://www.skyandtelescope.com/wp-content/uploads/Mira-tail_wide_800.jpg
Mira is as extraordinary scientifically as it is to observe. It's an enormous, ancient red giant, several hundred times the Sun's diameter. Like all red giants, it's shedding mass at a furious rate. A few years ago, NASA's Galex satellite discovered that Mira's discarded gases form a comet-like tail more than 2° long that glows brightly in the far ultraviolet.

If you want to estimate Mira's brightness for yourself, use the chart below. Selected comparison stars are labeled with their magnitudes, with the decimal points omitted.

Mira comparison-star magnitude chart
Mira is an easy target for binoculars and sometimes the naked eye. It lies about 10° southwest of the head of Cetus at right ascension 2h 19.3m, declination -2° 59'. Comparison-star magnitudes, courtesy the American Association of Variable Star Observers, are given to the nearest tenth with the decimal points omitted to avoid confusion with faint stars. Click on the chart for a larger image.

2 thoughts on “Observe Mira, the Amazing Star

  1. SREEDHAR RAO SONTI

    "Hold out your right hand at arm’s length with thumb and little finger outstretched. Put your thumb on Jupiter in the evening sky and tilt your hand clockwise a little; your little finger will be near Mira." I GUESS TILTING SHOULD BE ANTICLOCKWISE!

  2. Shari

    I did that and I did not see Mira — well I just did it at 3 am
    does it make a difference? Is it to late should this be done in the earlier part of the evening at 10pm

Comments are closed.