Throughout May and early June, the three most prominent constellations in the Northern sky are Hercules, Corona Borealis and Bootes.

Bootes - the Herdsman : in mythology, invented the plough drawn by two oxen.

Brightest star is Arcturus (alpha-Bootis ), the brightest star in the Northern Hemisphere ( mag -0.04). To find it, follow the tail of the Great Bear around in a curve until you come to the orange-giant K-type star. Below and in the same binocular field as epsilon, is the red variable W-Bootis. An M-type red giant, it pulsates with a semi-regular period of about 450 days, varying between magnitude 4.7 to 5.4. Both  epsilon and zeta  are binaries, but with separation less than 3 seconds of arc. An easier double is mu , whose components ( mag.4.3 and 7.0 ) are separated by 171".

Corona Borealis - the Northern Crown : is shaped like a bowl.

The brightest star is Alphekka (alpha-Coronae) with magnitude 2.2, while the others range between 3.7 and 4.1. In the bowl itself, two faint stars may be seen using binoculars; one is a normal star (mag 6.6) while the other, R Coronae, is usually mag. 5.8 but fades, unpredictably to below 15, recovering eventually to normal brightness. It is a 'sooty' star, surrounded by a shell of dust 33 light years across. Clouds of carbon in the star's atmosphere periodically dim its light.

Hercules : is rather like a poor copy of Orion in outline, but with no stars brighter than mag.2.8.

Rasalgethi  (alpha-Herculis) is a variable (discovered by William Herschel in 1795) which ranges between mag. 3 and 4. It is a red supergiant semi-regular variable with a period of 90 to 100 days, although it spends most of its time between mag. 3.1 and 3.5. Useful comparison stars are delta  ( 3.1 ), gamma ( 3.8 ) and kappa-Ophiuchi ( 3.2). There is a binary companion of mag. 5.4 at an angular separation of 4.7" which appears green by comparison with the ruddy primary.

Two globular clusters, M13 and M92, are easily visible with binoculars and a small telescope will begin to resolve individual stars on the edges of M13, which is the most impressive cluster in the Northern sky. At a distance of 22 500 light years, it contains nearly one million stars within a diameter of 150 light years. Quite possibly, a massive black hole lurks at its centre.

Planets :  Jupiter, Saturn and Mars are esentially too close to the Sun to be viewed safely until the end of May, when they have their first conjunction for two decades. Mercury is at greatest eastern elongation on June 9th. but is best placed for viewing on June 3rd. 45 minutes after sunset when it will shine with magnitude +0.1. It is close to Mars ( mag. +1.5) on May 19th.

July - August 2000      New Moon : 1st July, 31st July & 29th Aug.   Full Moon : 16th July & 15th Aug.

The 'Summer Triangle' : consists of the bright stars Deneb in Cygnus the swan , Vega in Lyra,  and Altair  in Aquila the Eagle .
Vega (mag. 0.0) is the brightest, Altair (0.8) is next while Deneb (1.2) is actually much more powerful but at a much greater distance (1800 l. y.). In 1983, Vega was found to be surrounded by a ring of dust which could suggest a planetary system. Between  beta and gamma,  lies the famous Ring Nebula ( M57 ). It is a planetary nebula - the remnant of a dying star - and was so-named by early observers because it appears as a 'planet-like' disc in small telescopes.

Beta Lyrae, close to M57, is a rare type of eclipsing binary, with a maximum magnitude of 3.3 dropping to 4.2, and rising to 3.8 at secondary minimum, with a period of 12.9 days. Its two components are so close together that they almost touch and they must be gravitationally distorted into egg-shapes, surrounded by swirling gas clouds.

The Milky Way runs through the constellation of Cygnus, also known as the Northern Cross, and it is well worth sweeping with binoculars. There are many variable stars, novae, open clusters and gaseous nebulae including NGC 7000, the North American Nebula, which lies within 3O of Deneb and which is a splendid sight through a wide-field telescopic eyepiece.

Albireo, (beta-Cygni) at the swan's head is a magnificent double through a small telescope or binoculars. The primary ( mag.3) is golden yellow while its fifth magnitude companion is vivid blue. The separation is over 34 seconds of arc and easily separable with firmly held binoculars. It is claimed, with ample justification, to be the most beautiful double star in the entire sky.

Altair in Aquila is the twelfth brightest star in the sky and is one of the nearest first magnitude stars at a distance of only 17 light years. Eta Aquila is one of the brightest Cepheid variables, ranging from mag.3.5 to 4.4 in a period of 7.2 days. Aquila is also a good place to search for novae - stars which suddenly increase in brightness by several magnitudes over a period of a few days and the fade slowly over the next few months. In 1918, a star near Theta Aquilae reached a magnitude of - 1.1 before fading from view, leaving behind a small planetary nebula ( which has since disappeared). In December 1999, Nova Aquilae 1999 reached magnitude 5.2 and was easily visible in binoculars.

Planets in July and August include Uranus and Neptune, both in the Southern Hemisphere constellation of Capricornus ( the Sea-Goat ). Neptune is at opposition on July 27th. mag. 7.8, diameter 2.5 arcsec and Uranus on August 11th. mag. 5.7, diameter 3.9 arcsec. Binoculars will show both if you know where to look and a telescope will reveal the greenish disc of Uranus and the bluish tint of Neptune, but surface details can be seen only with the Hubble telescope. Unfortunately, from the UK, both planets are very close to the horizon and not easily seen in light-polluted skies.

The Perseid meteor shower reaches its maximum around August 12th. It seldom disappoints with many bright meteors and fireballs and a zenith hourly rate of 80 at maximum.The best time to view is in the early hours of the 12th. when the 12-day old Moon has set and the radiant, near Gamma Persei, is above the horizon.

September - October 2000    New Moon : 27th Sept. & 27th Oct.  Full Moon :  13th Sept. & 13th Oct.

 The Square of Pegasus dominates the night sky in September - its four bright stars are: Markab (alpha), Scheat (beta), Algenib (gamma) and Alpheratz, which actually belongs to the adjoining constellation of Andromeda and is designated as  -Andromedae. They are all second magnitude stars, but Scheat is an M-class variable, ranging from mag. 2.3 to 2.9 with a semi-regular period of around 38 days - no two cycles are identical. 51-Pegasi is a 5th. magnitude star just outside the square roughly half-way between Alpha and Beta - it is a G3 type, similar to our Sun. In October 1995, 51-Peg. made the headlines as the first star around which a planet, with a mass about half that of Jupiter, had been detected.

Andromeda contains the famous Andromeda Galaxy (M31), located at the end of the line of stars formed by ,  and . To see it with the naked eye requires a clear dark night but binoculars reveal a ghostly patch of light - some claim to be able to make out its orientation. A small telescope will show its companion galaxies, M32 and NGC 205. M31 is the closest galaxy to our own Milky Way at a distance of  some 2.2 million light years. It is actually approaching our galaxy at a speed of 275 km/sec. A billion years from now, any life-forms in either galaxy will have a superb view of the other as they pass through each other in a blaze of star-formation.

November - December 2000    New Moon : 25th. Nov. & 25th. Dec.   Full Moon : 11th. Nov. & 11th. Dec.

November sees the return of magnificient Orion and his entourage. Taurus and the Pleiades are also prominent, as are the planets Jupiter and Saturn, making their return to the mid-heaven and so well-placed for observing. Jupiter is a brilliant - 2.8 throughout this period, reaching opposition on Nov. 28th. when it is only 600 million kilometres from Earth ( 33 light minutes ). Saturn is at opposition on Nov. 19th. and is at its most brilliant (mag. 0.0 ) in December.

This area is full of interesting objects, from open clusters of bright young stars to old red giants and supergiants, not to mention the Orion Nebula (M42) which is just a small part of an enormous molecular cloud complex some 1000 light years distant, where young stars are in the process of formation right now. In a few million years time, this region will be ablaze with bright new blue giant stars. The Crab Nebula (M1) in Taurus has a pulsar at the centre.

The Leonid meteor shower has attracted much attention in recent years, with some justification. Although it has not been possible to see the best of the show from the UK, it is still worth watching the skies carefully between the 15th. and 20th. of November. The peak of the shower still needs to be determined accurately to allow better predictions to be made in future and amateurs play a key role in this task.

Mars is close to the brilliant star Spica in Virgo during December but it rises later and later in the morning sky during January when it is in the constellation Libra. By the end of February it lies 6 degrees north of Antares in Scorpius with magnitude 0.5. It is at opposition on 10th. June 2001 (mag. -2.3) but with declination -26 degrees, it will not be best-placed for observers in the UK. Mars joins Pluto in Ophiuchus at the end of February. Pluto is a 14th. magnitude object, but it has been successfully captured using a CCD camera on a Meade LX10.

Planets in the evening sky include Jupiter and Saturn, and Venus is a brilliant Evening Star at mag. -4.6, but by April, Venus will have returned to the morning sky and Jupiter and Saturn will be sinking into the lengthening twilight after the Spring Equinox on March 21st. Mars rises after midnight by mid-April and is brightening as it approaches opposition but it remains close to the Southern horizon in Sagittarius.
 

January - February 2001     New Moon : 24th. Jan. & 23rd. Feb.   Full Moon :  9th. Jan. & 8th. Feb.

January sees the return of the Twins - Castor and Pollux in Gemini, the northernmost Zodiacal constellation. Although Castor (mag. 1.6) is designated Alpha Geminorum, Pollux is actually brighter (1.1). Castor is a well-known double star, the first to be recognised as such ( by William Herschel in 1803) and consists of two components of magnitudes 1.9 and 2.9. A 90mm telescope, such as the Meade ETX90, will resolve them well. The angular separation is 2.5 arc seconds and their orbital period is 420 years. The Milky Way crosses Gemini and is worth sweeping with binoculars for star clusters, such as the loose open cluster M35.

Cancer, the Crab, is home to a fine binocular or telescopic object, Praesepe or the 'Beehive' open cluster (M44). It is inferior only to the Pleiades and is a prominent naked-eye object except when the Moon is nearby or in a misty sky - around 280 BC, the Greeks used it to predict the onset of rain. Cancer is one of the faintest of the Zodiacal constellations, containing no stars brighter than Beta (mag. 3.5). One of the oldest open clusters is M67, which is just visible in binoculars. It is thought to be at least 4000 million years old - compared with only a few million years for the Pleiades.

March - April 2001     New Moon : 25th. Mar. &  23rd. Apr.     Full Moon :  9th. Mar. & 8th. Apr.

March sees the return of the regal Lion. Leo is one of the most convincing of the constellations in that it actually resembles the animal it represents. The bright star Regulus (mag. 1.4) is the most prominent. Apart from Beta and Gamma, the rest are magnitude 3 or fainter. There are several galaxies in Leo and the nearby Coma Berenices (Berenice's Hair) which gives its name to the Coma Cluster of galaxies which lies at a distance of 100 Megaparsecs ( over 300 million light years ) from our Local Group of galaxies.

The constellation of Coma looks like a star cluster, which it is. It consists of a very scattered group of naked eye stars, midway between Arcturus and Denebola ( Beta Leonis ) and covers an area about 5-degrees in diameter. There are more than a dozen stars above fifth magnitude and it is an impressive sight in binoculars or a telescope fitted with a wide-field Plossl eyepiece. In the same binocular field as Alpha, there is a bright globular cluster, M53, which is 69 000 light years away. There are five Messier galaxies: M64, M88, M98, M99 and M100 as well as three in the Caldwell list ( Patrick Moore's middle name is Caldwell ). The brightest of these is M64, the 'Black-Eye Galaxy' which is visible in binoculars and is 44 million light years distant. A largish telescope is needed to show any details however.

 References :

The Observer's Year                                   -   Patrick Moore ( Springer, 1998 )
Brilliant Stars                                               -   Patrick Moore ( Cassell ,1996 )
Exploring the Night Sky with Binoculars       -  Patrick Moore  (CUP - 3rd. ed. 1998 )
SkyMap Pro - Version 6                             -  Chris Marriott  ( 1992 - 1998 )
The Handbook , 2000                                 -  The British Astronomical Association