Your guide to the Solar System and the night sky
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🌎  Observing from: Greenwich, United Kingdom [change]
🌅 Sunrise: 5:54  ☀️ Transit: 12:05  🌅 Sunset: 18:16

21 Herculis

21 Herculis is a star in the constellation of Hercules.

21 Herculis visual magnitude is 5.85. Because of its reltive faintness, 21 Herculis should be visible only from locations with dark skyes, while it is not visible at all from skyes affected by light pollution.

The table below summarizes the key facts about 21 Herculis:

21 Herculis is above the horizon from Greenwich, United Kingdom [change]. Altitude: 40°.

Celestial coordinates and finder chart of 21 Herculis

21 Herculis is situated close to the celestial equator, as such, it is at least partly visible from both hemispheres in certain times of the year. Celestial coordinates for the J2000 equinox as well as galactic coordinates of 21 Herculis are provided in the following table:

16h 24m 10s
+06° 56’ 53”

The simplified sky map below shows the position of 21 Herculis in the sky:

Finder chart 21 Herculis star
Simplified finder chart for 21 Herculis.

Visibility of 21 Herculis from your location

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

Today's 21 Herculis rise, transit and set times from Greenwich, United Kingdom [change] are the following (all times relative to the local timezone Europe/London):

Azimuth: 83.1°
Max altitude: 45.5°
Azimuth: 276.9°
21 Herculis is above the horizon from Greenwich, United Kingdom

Digitized Sky Survey image of 21 Herculis

The image below is a photograph of 21 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 21 Herculis is 0.003 arcsec per year in Right Ascension and 0.014 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of 21 Herculis star
DSS2 image of 21 Herculis. The red arrow shows the motion of 21 Herculis during the next 10000 years (0.50 arcmin in Right Ascension and 2.33 arcmin in declination);

Distance of 21 Herculis from the Sun and relative movement

21 Herculis is distant 341.36 light years from the Sun and it is moving towards the Sun at the speed of 33 kilometers per second.

104.71 pc
341.36 ly
-33 km/s
0.003 arcsec/year
0.014 arcsec/year

Spectral properties of 21 Herculis

21 Herculis belongs to spectral class A2 21 Herculis is also a Sr chemically peculiar star.


The red dot in the diagram below shows where 21 Herculis is situated in the Hertzsprung–Russell diagram.

HR Diagram
H-R diagram showing the position of 21 Herculis. Attribution: Richard Powell / CC BY-SA

Alternative designations of 21 Herculis

21 Herculis