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Mira (Omicron Ceti, 68 Ceti) Star Facts

Mira Facts

  • Mira is a pulsating variable star that can be located in the constellation of Cetus. The description is based on the spectral class.
  • Mira is a main star of the constellation outline.
  • Based on the spectral type (M5e-M9e) of the star, the star's colour is red .
  • The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
  • Mira has a radius that is 332.00 times bigger than the Suns. Radius
  • Using the most recent figures given by the 2007 Hipparcos data, the star is 298.96 light years away from us. Distance

Mira's Alternative Names

Omicron Ceti (Omi Cet) is the Bayer Classification for the star. The Bayer Classification was created by Johann Bayer in 1603. The brightest star in the constellation is normally given the Alpha designation, there are exceptions such as Pollux which is Beta Geminorum.

The Id of the star in the Yale Bright Star Catalogue is HR681. HIP10826 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD14386.

Mira has alternative name(s) :- , omi Cet.

Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John named the stars in the constellation with a number and its latin name, this star's Flamsteed designation is 68 Ceti. The Flamsteed name can be shortened to 68 Cet.

The Gould star designation is one that was designed by American astronomer, Benjamin Apthorp Gould. Gould stars are predominantly in the Southern and Equatorial constellations but do appear in northern constellations such as Bootes and Orion. The star has the designation 233 G. Ceti. There are no stars with a Gould designation in Ursa Major for example.

BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD-03 353.

More details on objects' alternative names can be found at Star Names .

Location of Mira

The location of the variable star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the object is compared to the celestial equator and is expressed in degrees. For Mira, the location is 02h 19m 20.79 and -02° 58` 37.4 .

Radial Velocity and Proper Motion of Mira

Proper Motion

All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving -237.36 ± 1.31 milliarcseconds/year towards the north and 9.33 ± 1.22 milliarcseconds/year east if we saw them in the horizon.

Radial Velocity

The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is 63.50000 km/s with an error of about 0.60 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.

Physical Properties of Mira

Mira Temperature and Colour

Based on the star's spectral type of M5e-M9e , Mira's colour and type is red variable star. The star has a B-V Colour Index of 0.96 which means the star's temperature is about 5,060 Kelvin. The temperature was calculated using information from Morgans @ Uni.edu.

Mira Luminosity

Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 47.05 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.

Mira Radius

Mira Radius has been calculated as being 332.00 times bigger than the Sun. The Sun's radius is 695,800km, therefore the star's radius is an estimated 231,005,600.00.km. If you need the diameter of the star, you just need to multiple the radius by 2.

Mira Apparent and Absolute Magnitudes

Mira has an apparent magnitude of 6.47 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. If you used the 1997 Parallax value, you would get an absolute magnitude of 0.93 If you used the 2007 Parallax value, you would get an absolute magnitude of 1.66. Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.

Distance to Mira

Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 7.79000 which gave the calculated distance to Mira as 418.69 light years away from Earth or 128.37 parsecs. If you want that in miles, it is about 2,461,321,657,498,245.67, based on 1 Ly = 5,878,625,373,183.61 miles.

In 2007, Hipparcos data was revised with a new parallax of 10.91000 which put Mira at a distance of 298.96 light years or 91.66 parsecs. It should not be taken as though the star is moving closer or further away from us. It is purely that the distance was recalculated.

Using the 2007 distance, the star is roughly 18,906,100.40 Astronomical Units from the Earth/Sun give or take a few. An Astronomical Unit is the distance between Earth and the Sun. The number of A.U. is the number of times that the star is from the Earth compared to the Sun. The star's Galacto-Centric Distance is 7,466.00 Parsecs or 24,351.36 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.

Travel Time to Mira

The time it will take to travel to this star is dependent on how fast you are going. U.G. has done some calculations as to how long it will take going at differing speeds. A note about the calculations, when I'm talking about years, I'm talking non-leap years only (365 days).

The New Horizons space probe is the fastest probe that we've sent into space at the time of writing. Its primary mission was to visit Pluto which at the time of launch (2006), Pluto was still a planet.

DescriptionSpeed (m.p.h.)Time (years)
Walking450,121,886,851.46
Car1201,670,729,561.72
Airbus A380736272,401,558.98
Speed of Sound (Mach 1)767.269261,300,205.54
Concorde (Mach 2)1,534.54130,649,932.49
New Horizons Probe33,0006,075,380.22
Speed of Light670,616,629.00298.96

Variable Type of Mira

The star is a pulsating Omicron Ceti variable type which means that its size changes over time. The Variable Type is usually named after the first star of that type to be spotted. Mira brightness ranges from a magnitude of 7.321 to a magnitude of 2.935 over its variable period. The smaller the magnitude, the brighter the star. Its variable/pulsating period lasts for 333.8 days (variability).

Meteor Showers Radiating from near Mira

The August omicron Cetids Meteor Shower radiants from a point near this star. The meteor shower runs typically between with a peak date of 10th August. The speed of a meteor in the shower is 66 Km/s.

The Omicron Cetids Meteor Shower radiants from a point near this star. The meteor shower runs typically between May 7-June 9 with a peak date of May 14-25.

Source of Information

The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.

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Additional Mira Facts and Figures

Visual Facts


Primary / Proper / Traditional NameMira
Alternative NamesOmicron Ceti, Omi Cet, HD 14386, HIP 10826, HR 681, 233 G. Ceti, 68 Ceti, 68 Cet, BD-03 353, omi Cet
Spectral TypeM5e-M9e
Constellation's Main StarYes
Multiple Star SystemYes
Star TypeVariable Star
ColourRed
GalaxyMilky Way
ConstellationCetus
Absolute Magnitude 0.93 / 1.66
Visual / Apparent Magnitude6.47
Naked Eye VisibleYes - Magnitudes
Right Ascension (R.A.)02h 19m 20.79
Declination (Dec.)-02° 58` 37.4
Galactic Latitude-57.98223884 degrees
Galactic Longitude167.75430625 degrees
1997 Distance from Earth7.79000 Parallax (milliarcseconds)
 418.69 Light Years
 128.37 Parsecs
2007 Distance from Earth10.91000 Parallax (milliarcseconds)
 298.96 Light Years
 91.66 Parsecs
 18,906,100.40 Astronomical Units
Galacto-Centric Distance24,351.36 Light Years / 7,466.00 Parsecs
Proper Motion Dec.-237.36000 ± 1.31000 milliarcseconds/year
Proper Motion RA.9.33000 ± 1.22000 milliarcseconds/year
B-V Index0.96
Radial Velocity63.50000 ± 0.60 km/s
Eccentricity0.43640
Semi-Major Axis5037.0000000
Stellar Luminosity (Lsun)47.0500000

Companions (Multi-Star and Exoplanets) Facts


Exoplanet CountNone/Unaware

Variable Star Details


Variable Star ClassPulsating
Variable Star TypeOmicron Ceti
Mean Variability Period in Days333.800
Variable Magnitude Range (Brighter - Dimmer)2.935 - 7.321

Estimated Calculated Facts


Radius (x the Sun)332.00 (332.00 - 402.00)
Effective Temperature5,060 Kelvin

Sources and Links


SIMBAD SourceLink

Multi-Star System

The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.


Proper Motion mas/yr
H.D. IdB.D. IdStar CodeMagnitudeR.A.Dec.SpectrumColourYear
14386-03 353.0A-13.00000-233.00000M4Red
B13.000001911
14411-03 355.0C9.30000-6.00000-17.00000M1Red1925
P9.700001923

Location of Mira in Cetus


Mira Location in Cetus

The map was generated using Night Vision, an awesome free application by Brian Simpson.

Cetus Main Stars


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