We use cookies to deliver essential features and to measure their performance. By using this site you accept our Privacy Policies.
A Complete Guide to the Solar System and the Night Sky
Donate now and help us to keep this site free and ad-free!
public Observing fromLocation: Greenwich, United Kingdom edit_location_alt
north SunriseRise: 7:52  
clear_day Transit: 11:51  
SunsetSet: 15:49 south
sunny DaytimeWhat's Visible Now?
All Constellations » Aquila » 

21 Aquilae

Altitude: 18.0°   Azimuth: 109.9°   Direction: East-South-East

21 Aquilae is a variable and double bright giant star in the constellation of Aquila.

21 Aquilae visual magnitude is 5.15. Because of its reltive faintness, 21 Aquilae 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 Aquilae:

Bright giant

21 Aquilae is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 18.0°
Azimuth: 109.9°
Direction: East-South-East

Celestial coordinates and finder chart of 21 Aquilae

21 Aquilae 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 Aquilae are provided in the following table:

19h 13m 42s
+02° 17’ 36”

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

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

Visibility of 21 Aquilae 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 Aquilae 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: 87.7°
Max altitude: 40.8°
Azimuth: 272.3°

Digitized Sky Survey image of 21 Aquilae

The image below is a photograph of 21 Aquilae 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 Aquilae is 0.009 arcsec per year in Right Ascension and -0.003 arcsec per year in Declination and the associated displacement for the next 100000 years is represented with the red arrow.

Image of 21 Aquilae star
DSS2 image of 21 Aquilae. The red arrow shows the motion of 21 Aquilae during the next 100000 years (15.00 arcmin in Right Ascension and -5.00 arcmin in declination);

Distance of 21 Aquilae from the Sun and relative movement

21 Aquilae is distant 640.47 light years from the Sun and it is moving towards the Sun at the speed of 5 kilometers per second.

196.46 pc
640.47 ly
-5 km/s
0.009 arcsec/year
-0.003 arcsec/year

Spectral properties of 21 Aquilae

21 Aquilae belongs to spectral class B8 and has a luminosity class of II corresponding to a bright giant star.


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

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

21 Aquilae star system properties

21 Aquilae 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 Aquilae double sysyem:

36.2 arcsec

Alternative designations of 21 Aquilae