The Zodiacal Sky:
Finding Leo & Virgo from
The Big Dipper
by Martin J. Powell
The well-known asterism (star group) known as The Big Dipper (or The Plough) in Ursa Major (The Great Bear) can be used as a starting point to finding Leo and Virgo in the night sky (provided these constellations are above the observer's horizon at the required time). Click on the accompanying thumbnail to see the full-size diagram (29 KB).
To find Leo, use 'The Pointer Stars' Dubhe (pronounced 'DUB-ee', Ursae Majoris) and Merak ( Ursae Majoris) in the opposite direction from Polaris ( Ursae Minoris, the 'Pole Star') as indicated in the animation.
To find Virgo, use the 'handle stars' of The Dipper (the 'handle' of The Saucepan) to project an arc in a Southward direction until you come across the bright, orange-coloured star Arcturus ( Bo÷tis) in the constellation of Bo÷tes (pronounced 'Boe-OH-teez'), The Herdsman.
From Arcturus, continue the arc Southwards to the bright star Spica (pronounced 'SPY-kah', or Virginis), the brightest star in Virgo.
Note that this method primarily applies to Northern hemisphere observers. Southern hemisphere observers can only use this method if they are situated North of latitude 28░ South (The Big Dipper is not wholly visible at latitudes further South than this). Observers at mid-Southern latitudes should instead use the AstroViewer Java applet detailed on this site's main page.
The lines pointing to Leo and Virgo from The Big Dipper can also be seen in the form of an animation (1.3 MB).
Copyright Martin J Powell 2009
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