Your guide to the Solar System and the night sky
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🌎  Observing from: Greenwich, United Kingdom [change]

21 Aquarii

21 Aquarii is a giant star in the constellation of Aquarius.

21 Aquarii visual magnitude is 5.49. Because of its reltive faintness, 21 Aquarii 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 Aquarii:

21 Aquarii is below the horizon from Greenwich, United Kingdom [change].

Celestial coordinates and finder chart of 21 Aquarii

21 Aquarii 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 Aquarii are provided in the following table:

21h 25m 17s
-03° 33’ 24”

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

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

Visibility of 21 Aquarii from your location

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

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

Azimuth: 93.6°
Max altitude: 35.0°
Azimuth: 266.4°
21 Aquarii is below the horizon from Greenwich, United Kingdom

Digitized Sky Survey image of 21 Aquarii

The image below is a photograph of 21 Aquarii 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 Aquarii is -0.008 arcsec per year in Right Ascension and -0.065 arcsec per year in Declination and the associated displacement for the next 10000 years is represented with the red arrow.

Image of 21 Aquarii star
DSS2 image of 21 Aquarii. The red arrow shows the motion of 21 Aquarii during the next 10000 years (-1.33 arcmin in Right Ascension and -10.83 arcmin in declination);

Distance of 21 Aquarii from the Sun and relative movement

21 Aquarii is distant 408.01 light years from the Sun and it is moving towards the Sun at the speed of 24 kilometers per second.

125.16 pc
408.01 ly
-24 km/s
-0.008 arcsec/year
-0.065 arcsec/year

Spectral properties of 21 Aquarii

21 Aquarii belongs to spectral class K4 and has a luminosity class of III corresponding to a giant star.


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

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

Alternative designations of 21 Aquarii