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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: 7:49  
clear_day Transit: 11:49  
SunsetSet: 15:50 south
sunny DaytimeWhat's Visible Now?
All Constellations » Aries » 

21 Arietis

Altitude: -9.4°   Azimuth: 26.2°   Direction: North-North-East

21 Arietis is a double main-sequence star in the constellation of Aries.

21 Arietis visual magnitude is 5.58. Because of its reltive faintness, 21 Arietis 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 Arietis:


21 Arietis is below the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: -9.4°
Azimuth: 26.2°
Direction: North-North-East

Celestial coordinates and finder chart of 21 Arietis

21 Arietis 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 21 Arietis are provided in the following table:

02h 15m 42s
+25° 02’ 35”

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

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

Visibility of 21 Arietis 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 21 Arietis 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: 65.0°
Max altitude: 63.6°
Azimuth: 295.0°

Digitized Sky Survey image of 21 Arietis

The image below is a photograph of 21 Arietis 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 Arietis is -0.088 arcsec per year in Right Ascension and -0.087 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of 21 Arietis star
DSS2 image of 21 Arietis. The red arrow shows the motion of 21 Arietis during the next 10000 years (-14.67 arcmin in Right Ascension and -14.50 arcmin in declination);

Distance of 21 Arietis from the Sun and relative movement

21 Arietis is distant 156.96 light years from the Sun and it is moving towards the Sun at the speed of 44 kilometers per second.

48.15 pc
156.96 ly
-44 km/s
-0.088 arcsec/year
-0.087 arcsec/year

Spectral properties of 21 Arietis

21 Arietis belongs to spectral class F6 and has a luminosity class of V corresponding to a main-sequence star.


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

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

21 Arietis star system properties

21 Arietis is a visual double star which can be observed only with the help of very large telescopes. The table below shows key information about the 21 Arietis double sysyem:

0.2 arcsec

Alternative designations of 21 Arietis