Located at or near the overhead point during the spring night sky, as seen from mid-northern latitudes, is the familiar shape of the Plough formed from the seven brightest stars in the constellation Ursa Major (the Great Bear). The rest of the Great Bear stretches out to the west of the Plough, while immediately to its north is part of the long and winding constellation Draco (the Dragon), including the two stars Ed Asich and Thuban.
If you follow the line from Merak, through Dubhe, both located in the ‘bowl’ of the Plough, you will reach Polaris, the Pole Star (not shown on this chart – see North Circumpolar Stars). Polaris is the brightest star in Ursa Minor (the Little Bear) and marks the location of the north celestial pole.
The famous naked-eye double formed from Alcor and Mizar lies in the Plough ‘handle’, and located just to the south of the Plough are the faint constellations Canes Venatici (the Hunting Dogs) and Coma Berenices (Berenice’s Hair). Following the curve of the line of stars in the Plough handle southwards as shown here will take you to Arcturus, the leading star in the constellation Boötes (the Herdsman). Extending the line further will eventually lead you to Spica, the brightest star in the constellation Virgo (the Virgin). Coma Berenices lies within the Diamond of Virgo, a prominent asterism formed from the bright stars Arcturus in Boötes, Spica in Virgo, Denebola in Leo and Cor Caroli in Canes Venatici.
The other prominent group in this region of sky is Leo (the Lion) located to the north west of Virgo. If the sky is dark and clear, you should be able to pick out the small and rather faint constellations Leo Minor (the Little Lion) and Lynx (the Lynx), both of which are located in the area of sky just to the north of Leo. Clear skies will also be needed to reveal the small constellations Corvus (the Crow) and Crater (the Cup) to the south and southwest of Virgo. An even bigger challenge is to pick out the tiny Sextans (the Sextant), found a little way to the south of the bright star Regulus in Leo.
Spanning the skies to the south of Corvus, Crater and Sextans is the long and winding constellation Hydra (the Water Snake). The brightest star in Hydra is Alfard, found just to the west of Sextans, from where the rest of the group stretches away. Try finding Alfard and then, with binoculars, make your way along the body of the Water Snake! As you travel eastwards along Hydra you will come to the Mira-type long-period variable star R Hydrae. This type of variable is named after the famous variable star Mira in the constellation Cetus (see Autumn Constellations). R Hydrae varies in magnitude between around 4.5 and 9.5, the whole cycle taking place over a period of around 385 days. This fascinating object is easy to find, being located a little to the south of the brilliant star Spica in Virgo. R Hydrae is regarded as being one of the easiest variable stars to observe and is an ideal target for binoculars or a small telescope, or even the naked eye when the star is at or near maximum brightness!
Once you have managed to pick R Hydrae out, keep an eye on it over the following few weeks or months and watch as it slowly undergoes changes in brightness. As is the case with any variable star which remains at or near minimum brightness for extended periods, R Hydrae may be near its minimum magnitude and out of view when you first look for it. If this is the case, keep an eye open and it will eventually reappear. You can then follow it and keep an eye on its progress. Continued and careful observation of R Hydrae over a period of several weeks will reveal its variations in magnitude.
Moving further into the southern sky we arrive at Antlia (the Air Pump) and Pyxis (the Mariner’s Compass), two tiny and fairly inconspicuous constellations located to the north of the larger and brighter Vela (the Sail). Immediately to the south of Vela we see part of Carina (the Keel), these two constellations together playing host to the asterism the ‘False Cross’ which is formed from two stars in Carina and two in Vela. The False Cross is often confused with nearby Crux (the Cross) which is located some way to the east.
The tiny but distinctive Crux is surrounded by the southern reaches of Centaurus (the Centaur), its two brightest stars Alpha and Beta Centauri particularly prominent. Centaurus is bordered to the east by the constellation Lupus (the Wolf).