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A Complete Guide to the Solar System and the Night Sky
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public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 7:41  
clear_day Transit: 11:47  
SunsetSet: 15:53 south
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All Constellations » Perseus » 

θ Persei (theta Persei)

Altitude: 20.7°   Azimuth: 325.7°   Direction: North-West

θ Persei is a variable and multiple main-sequence star in the constellation of Perseus.

θ Persei visual magnitude is 4.12. Because of its moderate brightness, θ Persei should be easily visible from locations with dark skyes, while it can be barely visible, or not visible at all, from skyes affected by light pollution.

The table below summarizes the key facts about θ Persei:


θ Persei (theta Persei) is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 20.7°
Azimuth: 325.7°
Direction: North-West

Celestial coordinates and finder chart of θ Persei

θ Persei is situated north of the celestial equator, as such, it is more easily visible from the northern hemisphere. Celestial coordinates for the J2000 equinox as well as galactic coordinates of θ Persei are provided in the following table:

02h 44m 12s
+49° 13’ 41”

The simplified sky map below shows the position of θ Persei in the sky:

Finder chart θ Persei (theta Persei) star
Simplified finder chart for θ Persei (theta Persei).

Visibility of θ Persei from your location

Location: Greenwich, United Kingdom edit_location_alt
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

θ Persei (theta Persei) is circumpolar and transits at 22:02 UTC (altitude: 87.7°)

Digitized Sky Survey image of θ Persei

The image below is a photograph of θ Persei from the Digitized Sky Survey 2 (DSS2 - see the credits section) taken in the red channel. The area of sky represented in the image is 0.5x0.5 degrees (30x30 arcmins). The proper motion of θ Persei is 0.336 arcsec per year in Right Ascension and -0.089 arcsec per year in Declination and the associated displacement for the next 1000 years is represented with the red arrow.

Image of θ Persei (theta Persei) star
DSS2 image of θ Persei. The red arrow shows the motion of θ Persei during the next 1000 years (5.60 arcmin in Right Ascension and -1.48 arcmin in declination);

Distance of θ Persei from the Sun and relative movement

θ Persei is distant 36.62 light years from the Sun and it is moving far from the Sun at the speed of 25 kilometers per second.

11.23 pc
36.62 ly
25 km/s
0.336 arcsec/year
-0.089 arcsec/year

Spectral properties of θ Persei

θ Persei belongs to spectral class F8 and has a luminosity class of V corresponding to a main-sequence star.


The red dot in the diagram below shows where θ Persei is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of θ Persei. Attribution: Richard Powell / CC BY-SA

θ Persei star system properties

θ Persei is a visual double star which can be observed with the help of small or medium telescopes. The table below shows key information about the θ Persei double sysyem:

19.6 arcsec

Alternative designations of θ Persei

θ Persei
(theta Persei)
Gl 107 A