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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: 7:50  
clear_day Transit: 11:50  
SunsetSet: 15:49 south
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All Constellations » Hercules » 

ζ Herculis (zeta Herculis)

Altitude: 30.6°   Azimuth: 283.5°   Direction: West-North-West

ζ Herculis is a variable and double hypergiant star in the constellation of Hercules.

ζ Herculis visual magnitude is 2.81. Thanks to its high brightness, ζ Herculis is clearly visible when observed from locations with dark skyes, and should be also quite easily visible from light polluted areas.

The table below summarizes the key facts about ζ Herculis:


ζ Herculis (zeta Herculis) is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 30.6°
Azimuth: 283.5°
Direction: West-North-West

Celestial coordinates and finder chart of ζ Herculis

ζ Herculis 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 ζ Herculis are provided in the following table:

16h 41m 17s
+31° 36’ 11”

The simplified sky map below shows the position of ζ Herculis in the sky:

Finder chart ζ Herculis (zeta Herculis) star
Simplified finder chart for ζ Herculis (zeta Herculis).

Visibility of ζ Herculis from your location

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

Today's ζ Herculis (zeta Herculis) rise, transit and set times from Greenwich, United Kingdom edit_location_alt are the following (all times relative to the local timezone Europe/London):

Azimuth: 58.4°
Max altitude: 70.1°
Azimuth: 301.6°

Digitized Sky Survey image of ζ Herculis

The image below is a photograph of ζ Herculis 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 ζ Herculis is -0.47 arcsec per year in Right Ascension and 0.394 arcsec per year in Declination and the associated displacement for the next 1000 years is represented with the red arrow.

Image of ζ Herculis (zeta Herculis) star
DSS2 image of ζ Herculis. The red arrow shows the motion of ζ Herculis during the next 1000 years (-7.83 arcmin in Right Ascension and 6.57 arcmin in declination);

Distance of ζ Herculis from the Sun and relative movement

ζ Herculis is distant 35.19 light years from the Sun and it is moving towards the Sun at the speed of 70 kilometers per second.

10.80 pc
35.19 ly
-70 km/s
-0.47 arcsec/year
0.394 arcsec/year

Spectral properties of ζ Herculis

ζ Herculis belongs to spectral class G0 and has a luminosity class of IV corresponding to a hypergiant star.


The red dot in the diagram below shows where ζ Herculis is situated in the Hertzsprung–Russell diagram.

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

ζ Herculis star system properties

ζ Herculis is a visual double star which can be observed with the help of large telescopes. The table below shows key information about the ζ Herculis double sysyem:

1.1 arcsec

Alternative designations of ζ Herculis

ζ Herculis
(zeta Herculis)
40 Herculis
Gl 635 A