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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: 7:48  
clear_day Transit: 11:49  
SunsetSet: 15:50 south
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All Constellations » Hercules » 

42 Herculis

Altitude: 66.9°   Azimuth: 278.1°   Direction: West

42 Herculis is a variable and double giant star in the constellation of Hercules.

42 Herculis visual magnitude is 4.9. Because of its moderate brightness, 42 Herculis 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 42 Herculis:


42 Herculis is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 66.9°
Azimuth: 278.1°
Direction: West

Celestial coordinates and finder chart of 42 Herculis

42 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 42 Herculis are provided in the following table:

16h 38m 44s
+48° 55’ 41”

The simplified sky map below shows the position of 42 Herculis in the sky:

Finder chart 42 Herculis star
Simplified finder chart for 42 Herculis.

Visibility of 42 Herculis from your location

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

42 Herculis is circumpolar and transits at 11:38 UTC (altitude: 87.4°)

Digitized Sky Survey image of 42 Herculis

The image below is a photograph of 42 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 42 Herculis is -0.047 arcsec per year in Right Ascension and 0.031 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of 42 Herculis star
DSS2 image of 42 Herculis. The red arrow shows the motion of 42 Herculis during the next 10000 years (-7.83 arcmin in Right Ascension and 5.17 arcmin in declination);

Distance of 42 Herculis from the Sun and relative movement

42 Herculis is distant 376.01 light years from the Sun and it is moving towards the Sun at the speed of 55 kilometers per second.

115.34 pc
376.01 ly
-55 km/s
-0.047 arcsec/year
0.031 arcsec/year

Spectral properties of 42 Herculis

42 Herculis belongs to spectral class M2 and has a luminosity class of III corresponding to a giant star.


The red dot in the diagram below shows where 42 Herculis is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of 42 Herculis. Attribution: Richard Powell / CC BY-SA

42 Herculis star system properties

42 Herculis 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 42 Herculis double sysyem:

25.6 arcsec

Alternative designations of 42 Herculis

42 Herculis