Finding Stars and Constellations – Part IV

This post continues the series Finding Stars and Constellations.    

Boötes  The Herdsman   If we take a line from Alioth to Alkaid in the Great Bear and extend that line in an -imaginary curve for about roughly three hand-spans as shown in the diagram below, it will point to Arcturus, the brightest star in the constellation Bootes.

bootesBoötes is the 13th largest constellation and is located in the northern hemisphere and can be seen from +90 to -50.  The ancient Greeks visualized it as a herdsman chasing Ursa Major round the North Pole and its name is derived from the Greek for “Herdsman”.

Arcturus is the fourth brightest star in the sky and is a navigation star; it can be seen during nautical twilight in June.  The ancient Greeks named Arcturus the “Bear Watcher”  because it seems to be looking at the Great Bear (Ursa Major).

Corona Borealis, The Northern Cross   If we next take a line from Nekkar to Princepes in Boötes, and extend that line by about one and a half hand-spans, it will point to Nusakan and on to Alphecca in the nearby Corona Borealis constellation.

bootes and corona

Corona Borealis, whose name in latin means northern crown, is a small constellation in the northern hemisphere and can be seen between latitudes +90 to -50. Alphecca, the brightest star in the group, is a navigation star and is best seen during evening nautical twilight in July.

The main stars in Corona Borealis form a semi-circle which is associated with the crown of Ariadne in Greek mythology.  It said that the crown was given to Ariadne by Dionysus on their wedding day and after the wedding, he threw it into the sky where the jewels became stars which were formed into a constellation in the shape of a crown.

Virgo, the Virgin

 virgodrawingThe constellation Virgo takes its name from the Latin for virgin or young maiden.  In ancient Greek mythology, Virgo is associated with the goddess Dike, the goddess of justice and as the diagram below shows, the constellation Libra, the scales of justice, lies next to Virgo.

Virgo lies over the southern hemisphere and is one of the largest constellations in the sky, smaller in size only to  Hydra.  It is visible between latitudes +80 to -80 and for navigation purposes, it is best seen during evening nautical twilight in May.

The brightest star in Virgo is Spica, the 15th. brightest star in the sky and a navigation star.

Finding Virgo.

As we learned when studying the constellation Boötes, an imaginary curved line from Alkaid in the Great Bear leads to the bright orange star Arcturus, in the constellation Boötes.  If, as shown in the following diagram, we continue that curved line by another hand span from Arcturus we will come to the bright bluish-white star Spica, in the constellation Virgo which is to the left of Leo.

beartobootesto virgo and leo

Notes.    Star maps can be very confusing because they are not drawn in the conventional way with east on the right and west on the left.  They are drawn as they would appear in the sky if we were lying down with our legs pointing to the south and looking upwards so that east would be on the left and west on our right.

Although this series of posts show the locations of certain constellations relative to other constellations in the sky, it does not necessarily indicate whether or not they will be visible above the horizon.  That will of course depend on its times of rising and setting at the  position of the observer.  ‘Risings and Settings’ will be the subject of another post.

Watch out for the next post in this series which will be issued shortly.

Links:   

Finding Stars and Constellations Part I

Finding Stars and Constellations Part II

Finding Stars and Constellations Part III

Rising and setting times of stars.

Latitude from Polaris

Astro Navigation Demystified on Amazon

The Application of Mathematics To Astro Navigation on Amazon

About Astro Navigation Demystified