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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
SunriseRise: 7:03  
clear_day Transit: 12:12  
SunsetSet: 17:22
sleep NighttimeWhat's Visible Now?
All Constellations » Boötes » 

Arcturus - α Boötis (alpha Boötis)

Altitude: 7.8°   Azimuth: 68.9°   Direction: East-North-East

Arcturus, also designated as α Boötis (alpha Boötis), is a variable giant star in the constellation of Boötes.

Arcturus visual magnitude is -0.04, making it the third brightest star in the sky. Thanks to its high brightness, Arcturus is clearly visible when observed from locations with dark skyes, and should be also quite easily visible from light polluted areas.

The proper motion of Arcturus is -1.093 arcsec per year in Right Ascension and -1.998 arcsec per year in Declination and the associated displacement for the next 100 years is represented with the red arrow.

Image of Arcturus - α Boötis (alpha Boötis) star
DSS2 image of Arcturus. The red arrow shows the motion of Arcturus during the next 100 years (-1.82 arcmin in Right Ascension and -3.33 arcmin in declination);

Key facts about Arcturus

-0.04
Giant

Arcturus - α Boötis (alpha Boötis) is above the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: 7.8°
Azimuth: 68.9°
Direction: East-North-East

Celestial coordinates and finder chart of Arcturus

Arcturus 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 Arcturus are provided in the following table:

14h 15m 39s
+19° 10’ 57”
15.14°
69.11°
Boötes

The simplified sky map below shows the position of Arcturus in the sky:

Finder chart Arcturus - α Boötis (alpha Boötis) star
Simplified finder chart for Arcturus - α Boötis (alpha Boötis).

Visibility of Arcturus 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 Arcturus - α Boötis (alpha Boötis) 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: 70.8°
Max altitude: 57.7°
Azimuth: 289.2°

Distance of Arcturus from the Sun and relative movement

Arcturus is distant 36.69 light years from the Sun and it is moving towards the Sun at the speed of 5 kilometers per second.

11.25 pc
36.69 ly
-5 km/s
-1.093 arcsec/year
-1.998 arcsec/year

Spectral properties of Arcturus

Arcturus belongs to spectral class K1 and has a luminosity class of III corresponding to a giant star.

-0.30
K1III
4251K

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

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

Alternative designations of Arcturus

Arcturus
α Boötis
(alpha Boötis)
SAO100944
SAO100944