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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: 7:50  
clear_day Transit: 11:50  
SunsetSet: 15:49 south
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All Constellations » Ophiuchus » 

Rasalhague - α Ophiuchi (alpha Ophiuchi)

Altitude: -4.8°   Azimuth: 297.1°   Direction: West-North-West

Rasalhague, also designated as α Ophiuchi (alpha Ophiuchi), is a variable giant star in the constellation of Ophiuchus.

Rasalhague visual magnitude is 2.08, making it the 59th brightest star in the sky. Thanks to its high brightness, Rasalhague is clearly visible when observed from locations with dark skyes, and should be also quite easily visible from light polluted areas.

The table below summarizes the key facts about Rasalhague:


Rasalhague - α Ophiuchi (alpha Ophiuchi) is below the horizon from Greenwich, United Kingdom edit_location_alt.

Altitude: -4.8°
Azimuth: 297.1°
Direction: West-North-West

Celestial coordinates and finder chart of Rasalhague

Rasalhague 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 Rasalhague are provided in the following table:

17h 34m 56s
+12° 33’ 36”

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

Finder chart Rasalhague - α Ophiuchi (alpha Ophiuchi) star
Simplified finder chart for Rasalhague - α Ophiuchi (alpha Ophiuchi).

Visibility of Rasalhague 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 Rasalhague - α Ophiuchi (alpha Ophiuchi) 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: 77.4°
Max altitude: 51.1°
Azimuth: 282.6°

Digitized Sky Survey image of Rasalhague

The image below is a photograph of Rasalhague 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 Rasalhague is 0.12 arcsec per year in Right Ascension and -0.226 arcsec per year in Declination and the associated displacement for the next 1000 years is represented with the red arrow.

Image of Rasalhague - α Ophiuchi (alpha Ophiuchi) star
DSS2 image of Rasalhague. The red arrow shows the motion of Rasalhague during the next 1000 years (2.00 arcmin in Right Ascension and -3.77 arcmin in declination);

Distance of Rasalhague from the Sun and relative movement

Rasalhague is distant 46.68 light years from the Sun and it is moving far from the Sun at the speed of 13 kilometers per second.

14.32 pc
46.68 ly
13 km/s
0.12 arcsec/year
-0.226 arcsec/year

Spectral properties of Rasalhague

Rasalhague belongs to spectral class A5 and has a luminosity class of III corresponding to a giant star.


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

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

Alternative designations of Rasalhague

α Ophiuchi
(alpha Ophiuchi)
55 Ophiuchi