The Rhythms of Life
By Ivor Clarke

We all enjoy the rhythms of music, the rhythms of the day and night.  The rise and set of the sun and moon.  The seasons and the years.  All this change we take for granted as the way our planet and nature works, we hope it will continue without too much alteration.  From the earliest days of mankind we have recorded the passing of time and have observed the heavens filled with stars and planets and our Moon.

We know each day brings a small change in the length of time the sun stays above the horizon, longer each day in spring and shorter in autumn.  We also know that each year repeats itself, even if the weather is different, and that the same stars will rise and fall at the same time every year.  As far as we humans are concerned, the only change belongs to the planets in the solar system.  These travel along their orbits and are forever in a different spot in the sky every day.  Or are they?
The Earth completes an orbit of the sun in a year of 365.256 days and the Moon goes round the Earth in 27·3 days, Mercury orbits in 88 days and Venus in 224·7, Mars 687 days, Jupiter 11·86 years and Saturn 29·45 years, Uranus in 84 years, Neptune in 164·8 years and distant Pluto in 248·5 years.  This arrangement has gone on like this for maybe nearly a third of the life of our universe!

An amazing thought.

So let us start at the beginning and look at the length of our day.  It was not always 24 hours long.  Very early in the history of planet Earth, it was about half what it is now, something less then 12 hours.  This fast spin may have been caused by the body which crashed into the early Earth, causing the Moon to form in low orbit from the splash of its impact smashing into our planet.  This impactor is suspected of being a body larger in size than Mars.  Luckily this happened about 60M years, after the formation of the Earth, so the consequences weren?t as dire to any life forms as they might have been!
This crash could also have given our planet its  inclination of 23.5°.  However this tilt alters over eons as the Earths core moves slightly differently to the rocks above it.  At the present time the core spins a quarter of an hour quicker per year than the surface!

The Moon is also responsible for holding the axis of the Earth in an upright position and not allowing it to tilt to far over, such as the planet Uranus giving us month long days twice a year.  The effect of the Moon on the oceans is slowly slowing down the length of the day by friction of the tides on the land masses.  The transfer of angular momentum is pushing the Moon further out so its effect will lesson as its orbital distance increases.
The sun too has its rhythms with the well known sunspot cycle of 11·1 years, although this is known to vary between 8 and 16 years.  The magnetic fields of the sun have a period of twice the sunspot cycle at around 22 years.  The magnetic fields inside the sunspots exchange polarity in successive cycles with a preceding spot first having northern polarity and the following spot southern polarity, then reversing for the next cycle.

While all the planets orbit the sun in the same direction (anti-clockwise from a position above the north pole) and roughly in the same orbital plane.  They also interact with each other through the small gravitational pulls each makes on the other as they pass by.  Most of these interactions will, over the life time of our solar system, cause a small shift in the position of a neighbouring body until it balances with the other forces acting on it.  So most of the planets orbit the sun in a resonance with other bodies which keeps them locked in position.  These are small but significant over time, for instance, the mass of Jupiter is 1/1000 that of the sun.  This causes the sun to move in a small circular motion around a point opposite to were Jupiter is in its orbit.  All the other planets pull on the sun too, but because of their lower mass their effect is much smaller.
Venus and the Earth repeat their positions in respect to each other after 211 years when a double transit of Venus will occur with a gap of 8 years.  There will also be a double transit after 105·5 years after the last transit but this takes place on the other side of the sun, either in June or 6 months later in December.

Likewise the Moon returns to the exact position it was in, in its orbit after 18 years, 111/3 days, (for a 4 leap year span).  This is the Saros cycle of 223 lunations or 6585·32 days.  This was known to the Chaldeans more than 2,000 years ago.  They discovered this cycle by observing solar eclipses, and noting that they returned to the same longitude after 54 years, a triple Saros.
The sun of cause holds its grip most of all on Mercury as it speeds on its 88 day orbit.  It was expected that it would have a gravitational locked rotation to the sun with one side hot and the other freezing.  So it was a surprise to find in 1968 that it rotated in 58·7 days, exactly two-thirds of its orbital period.  Mercury transits the sun at intervals of 7, 13 and 46 years, according to circumstances, when it either transits in November (more common) or May.  This cycle will then repeat itself.
What we are seeing is that all of nature is governed by rhythms caused by the interaction with other objects.  All the bodies in the solar system effect each other, the larger obversely having a greater effect on the smaller.  Don?t forget that the Earth is the fifth largest body in the solar system, so has a large influence on all the inner planets.

Further out the asteroid belt between Mars and Jupiter is not a smooth spread of objects.  It has groups of concentrated material at resonance points.  Other resonances points in the asteroid belt are marked by gaps called the Kirkwood gaps which are caused by Jupiter?s gravity.  This has, over time, cleaned out areas by the slight tugging caused by Jupiter?s gravity on the smaller bodies orbiting faster than Jupiter.  Asteroids orbit in exact fractions, 3/4 and 2/3, of Jupiter?s orbit safely, but other fractions 1/2 , 1/3 , 3/5 etc. cause gaps and holes.  This is not the same mechanism which forms the fine ring structure in the rings of Saturn as seen by Voyager; the F-ring shepherd satellites Prometheos and Pandora exchange orbits when passing each other.

Most of these rings are caused by small bodies in orbit clearing out particles in their orbit.  With Jupiter it is resonances of the orbital times which cause the groupings and the gaps.
One of the more remarkable orbits concerns the minor planet 1986 TO, asteroid number 3753.  Its orbit takes it just out side of Mercury?s orbit to a little beyond Mars!  This makes it one of the numerous Apollo family of bodies which come within Earth?s orbit, but the strange thing about its orbit is that the semimajor axis (which means its orbital time) varies from being just under 1 a.u. to just over 1 a.u. every 770 years.  It is not quite a 1 : 1 resonance with Earth.

What happens is that it spends 385 years slowly catching up with the Earth?s position in space and then swops energy with the Earth to spend the next 385 years slowly dropping behind again until the Earth catches it up and gives it a little push to help it complete the cycle!  Its orbital period varies between 363.67 and 366.85 days in each half of its cycle.
Other moons in our system are in resonance with their planet, for instance the three inner Galilean moons of Jupiter, Io, Europa and Ganymede follow a 2 : 1 resonance with each other.  Io orbits Jupiter in 42.5 hours, twice to Europa?s once and Europa orbits twice to each orbit of Ganyamede.  This forms a very stable relationship as the bodies can never come close to each other with the gravity of each slightly pushing and pulling the other, so keeping the balance with each orbit.

At Saturn the same 2 : 1 relationship exists between Mimas and Tethys as well as between Enceladus and Dione.  At Neptune a 4 : 1 resonance between Titan and Hyperion exists.  Further out the small body of Pluto has an orbital resonance of 2 : 3 with much larger Neptune.  Neptune controls the smaller Pluto and also most likely, thousands of other icy worlds in the Kuiper Belt.  I suspect this will be found to have gaps and holes the same as the asteroid belt has from the pull of Jupiter, but in this case from the pull of Neptune.

Other rhythms effect the Earth on much longer time scales, at present we are about 33 light years above the plane of our galaxy which the sun orbits around in 250 million years.  During each orbit the sun bobs up and down several times each side of the plane of the galaxy, sometimes passing through dust clouds which may dim the suns light for a time.
These and others forces acting on us have made life on our Earth possible by creating the right amount of variation and change to stimulate life to progress but not so much that it has killed it off.  If change is too rapid, ie. by a big rock dropping out of the sky!,  it will damage life.  The environment may change to quickly before the evolution process can fit and adapt the fauna and flora into the new mold.
Luckily for us this change in rhythm happens at a smooth pace in our bit of the universe.

The Astronomy of Tidal Bores
by Mike Frost

?The enormous wave which marches at the head of the tide swells, rises, stands up; it bursts of a sudden, and its summit falls with a crash; an immense roll is formed and unfolds itself, sometimes from one end to the other; it is a cascade which moves, which runs and remounts the river with the speed of a galloping horse.  The wall runs along like a wall of foam, overthrowing all obstacles and rearing itself up each instant like a gigantic plume, to fall again quivering on the bank, which it deluges.  The ground sometimes trembles under the feet of the spectators, who see, in less time than it takes to describe it, the boiling mass passing on and pursuing its ungovernable course*.
? Camille Flammarion, quoted in ?The Romance of Modern Astronomy* (1919)

Stand by the riverbank at Minsterworth, Gloucestershire, at around 10pm on October 7th, and, weather permitting, you will witness one of the most imposing natural sights in Britain ? the tidal bore on the river Severn.  Without warning, the stately flow of the river downstream toward the Bristol Channel will be interrupted by the arrival of a wall of water, a metre or more in height, moving rapidly upstream toward Gloucester.  What causes this strange phenomenon?  What factors affect it?s magnitude and the time of its arrival?  And why does it favour the River Severn?  A comprehensive discussion of these questions involves consideration of many sciences ? not least hydrology, fluid dynamics and meteorology.  Yet a surprising number of the factors involved in the formation of the largest tidal bores turn out to be astronomical in origin.

To answer one question ? although the bore on the River Severn is the largest in Britain, it is by no means the only one; indeed, most tidal rivers exhibit some sort of bore, although usually only centimetres in height.  Most rivers draining into the Bristol Channel, particularly the Parrett, have a bore similar to that on the Severn, and there are similar systems associated with the River Humber and the Wash.  The tidal bore on the River Trent, better known as the Aegir, can be best seen from around Gainsborough.  And the rapid arrival of the tide in the Solway Firth features in Redgauntlet, Sir Walter Scott?s tale of Jacobean rebellion in Border country. ?...for the tide advances with such rapidity on these fatal sands that well?mounted horsemen lay aside hopes of safety if they see its white surge advancing as they are yet at a distance from the beach.*

So what causes tidal bores?  In essence, the tidal bore can be thought of as the abrupt commencement of the flood tide.  Ordinarily, the level of the sea rises and falls in a regular oscillatory manner.  At most seaside locations, the tide comes in and out gradually, with an interval of approximately 12 hours 25 minutes between high tides.  A tidal bore forms when this sinusoidal behaviour is distorted by the geometry of the river bed.  When tides flow into an estuary or inlet where the depth rises steeply upwards, the profile of the incoming tide is modified.  Instead of the tide turning half way between high tides, the river level continues to drop.  When the incoming tide does arrive, the level rises rapidly, taking perhaps one or two hours to reach high tide.  The tidal bore is the most extreme case of this, where the first hint of a rising tide is the arrival of a wall of water.

Even if the river bed is a favourable shape, a tidal bore may still not form.  On the Severn, for example, bores only occur perhaps 130 days a year.  Tidal bores are generally likeliest and most impressive when the tides are highest.  To predict when the highest tides occur, we need to understand the effects which modify the tidal range ? and, of course, these are mostly astronomical.

The tides are caused by the gravitational attraction of the Moon and (to a lesser extent) the Sun.  Because one side of the Earth is approximately 8000 miles closer to the Moon than the other side, the Moon?s gravitational force on the near side is approximately 7% more than on the far side.  The average force exerted by the Moon on the Earth is required to give the centripetal acceleration of the Earth as it rotates around the centre of gravity of the Earth?Moon system.  Locally subtracting off this centripetal acceleration from the Moon?s gravity gives a differential force field which tries to deform the Earth into something like a rugby ball, with its longest axis pointing toward the Moon.  Because the Earth is essentially a rigid body, the deformation does not take place and the planet remains spherical.

However the waters of the oceans are free to respond to the differential force field.  If the Earth were completely covered with oceans, they would be pulled into two bulges, one beneath and one directly opposite the Moon, into which the solid Earth would rotate ? the time between bulges would be slightly more than half a day because of the Moon?s progression around its orbit.  The distribution of land mass complicates this simple picture considerably, but the dominant tidal oscillation remains one of 12.4 hrs, with a lag behind the Moon?s passage overhead which varies considerably from place to place.

The gravitational force due to the Sun on the Earth is much larger the Moon?s, so you might think that the corresponding tidal force was greater.  You would be mistaken; the size of the gravitational force is greater, but it?s variation across the Earth is much less; consequently tidal effects due to the Sun are only a half of those due to the Moon.  Clearly, however, the combined effects of these two tides are greatest when Sun and Moon are pulling together.  These are spring tides, which occur at New Moon and Full Moon, although for the Severn there is a lag of two days because of the landmass complications detailed above.

Whether the tide is highest at New or Full Moon depends on whether the Moon is closest to perigee at New or Full Moon.  The perigee, the point where the Moon is closest to Earth (and the gravitational attraction strongest), moves gradually around the Moon?s orbit, and consequently the highest tides will occur first for a run of Full Moons, then a similar run of New Moons.  During 1998 tidal bores on the Severn are best shortly after the New Moon in the first half of the year, and after the Full Moon in the second half.  If Full or New Moon co?incides with perigee tides are particularly high.

The Earth?s orbit around the Sun is itself elliptical, although not as eccentric as the Moon?s around Earth.  Consequently there is a bias of the height of tides towards January, when the Earth is closest to the Sun.  Of greater importance to the formation of tides, however, are the declinations of Sun and Moon.  Tides are greatest when Sun or  Moon is on the celestial equator.  The Moon?s crossings of the equator wander through the calendar, but the Sun?s appearance on the equator is more straightforward ? at the spring and vernal equinoxes (March 21st and September 21st).  The size of tidal bores gradually increase as an equinox approaches, then start to reduce toward midsummer or midwinter.

Which goes some way toward explaining a curious piece of folklore ? that the Severn bore only ever occurs on Good Friday.  For Easter Sunday is supposed to coincide with Passover, the closest full Moon to the spring equinox.  So Good Friday will usually be an excellent day to observe the Severn bore.  The ecumenical and astronomical calenders do not always coincide; however, up until recent years, Good Friday was often the only holiday anywhere close to the equinoxes ? the one chance for most people to observe the bore.

Apart from Good Friday, however, the best river bores are to be seen at the Full and New Moons closest to the equinoxes ? in 1998, these will be around March 1st, March 29th, and October 7th.  On the Severn, at these times of the year, the high tide will arrive at Minsterworth at around 10 in the morning and 10 in the evening.  Indeed, because of the phase lag of the tides, the highest bores on the Severn are to be found between 7 and 12 in the morning and 7 and 12 in the evening.

Whether morning bores are better than evening depends on whether the Moon is above or beneath the Celestial equator (and whether or not it is full, and don?t forget the phase lag!) ? in early October the bores are best in the evening.  Note however that the size of the bore is also dependent on several non-astronomical considerations, such as the wind speed and direction, and the barometric pressure, all of which can spoil or enhance the bore.  Finally, the presence of boats, canoes or surfers riding the bore, whilst providing scale and spectacle, can ?break the wave* and reduce its size.

Worldwide, many river systems exhibit bores greater in size than that on the Severn.  The Seine in northern France used to exhibit a sizeable bore called the ?Mascaret*.  Camille Flammarion, the notable French astronomer, wrote a vivid description which I have used to open this article; unfortunately, work on the river banks has now reduced the size of the Seine bore.  The Bay of Fundy, in Nova Scotia, Canada, has the world?s largest tides, which give rise to a substantial tidal bore.  The mouth of the Amazon and the Cook inlet in Alaska boast notable bores.  The biggest of all tidal bores, the guan chao or ?wonder tide*, is on the Qiantang Kiang, in Southern China.

The bore is also known as the ?black dragon* because of the river silt it carries.  It can reach up to 4.5m in height and has been known to wash away unwary cattle grazing on its banks.  The Chinese long ago built backwaters on the Qiantang Kiang in which river traffic could ride out the bore.
Which leads to one final intriguing event.  When are the tidal attractions of Moon and Sun most closely aligned?  At an eclipse, of course, when Earth, Moon and Sun lie in a straight line (not necessarily in that order).  And on July 22nd 2009, the path of a total solar eclipse passes directly across the Qiantang Kiang.  At 9:37 AM local time there is an eclipse of the Sun, and around two hours later, an unseasonably large bore on the world?s most boring river.  Quite a day!
 
 

The author would like to thank Mike Feist of Foredown Tower, Portslade, for historical sources, Eric Jones of the Proudman Oceanographic Laboratory for scientific assistance, and the Environment Agency for information on the Severn and Trent bores.
 

Sources:
?The Severn Bore* ? Fred Rowbotham (David and Charles, 1983)
?The Severn Bore and Trent Aegir 1998* ? Environment Agency
?The Romance of Modern Astronomy* ? Hector MacPherson, Jnr (1919)
?The Revolving Heavens ? Astronomy for Observers with the Naked Eye* ? Reginald L. Waterfield (Duckworth, 1944)
?McGraw Hill Encyclopaedia of Science and Technology* ? entries on tides and river bores (V12,18 1992)
?Redgauntlet* ? Sir Walter Scott (P33, OUP 1995)

Severn Bores for October 1998 (approx times at Minsterworth)
  Mon 5th Oct ? 08.19,  20.40
  Tue 6th Oct ? 09.02,  21.23
  Wed 7th Oct ? 09.45,  22.05
  Thu 8th Oct ? 10.26,  22.47
  Fri 9th Oct ?  11.06,  23.27

Evening bores are predicted to be better than morning bores, and bores towards the middle of the week are best ? but nothing is guaranteed!
Notable Tidal Bores of Britain :
  System     River
  Bristol Channel    Severn, Parrett and others
  Solway Firth
  Morecambe Bay    Lune
  Humber     Trent (Aegir) and others
  The Wash
Notable Tidal Bores of the world :
  River      Country  Name
  Amazon     Brazil   Porocora
  Cook Inlet, Alaska    USA
  Gulf of California    USA
  Bay of Fundy (Petitcodiac)   Canada
  Sittang     Burma
  Ganges (Hooghly,Brahmaputra)  India
  Indus      India
  Seine      France  Mascaret
  Qiantang Kiang    China   Guan Chao, Dragon

Diamond Rings and Golden Orioles
by Mike Frost

On February 26th 1998, a total eclipse of the Sun was visible along a track from north of the Galapagos Islands to west of the Canary Isles, passing over parts of Colombia, Venezuela and the Caribbean.  I travelled to Curacao in the Netherlands Antilles, 100 km north of the Venezuelan coast, with a party from Explorers Tours.  The centre line of totality passed just to the north of the island, but from our chosen observing site we could still expect to see 3 min 26 seconds of total eclipse, weather permitting.

As the 26th dawned, conditions did not look good from Willemstad, the chief town of Curacao.  There was heavy cloud cover and even a dispiriting sprinkle of rain.  However, local opinion was that the sun would burn off cloud cover during the morning.  Even as we made our way north by minibus convoy, their predictions seemed to be coming true.  The appearance of the Sun from behind a cloud was greeted with delight.

Our observing site was called Knip Bay, a few miles south of the tip of the island.  It was a beautiful cove carved into limestone cliffs, a sandy valley with shady tree cover surrounded by formidable cactus fields.  A pair of orioles, black apart from golden wings and a streak of ?suntan lotion* beneath the eyes, watched the proceedings nervously from the periphery of the beach.  Knip bay was packed!  Half the bay had been cordoned off for our party, the rest was full of locals who had taken the day off and were swimming and splashing prior to viewing the eclipse.  An impressive variety of craft, from jet skis to cabin cruisers, were moored offshore.

First contact of Moon on Sun was at 11:40am local time, and many of the party began observing the Sun through eclipse shades and filters, or via projection.  Other astronomers (me included) went for a dip!  Two collections of sunspots were visible.  As the Moon?s disk began to progress gradually across the Sun, the cloud cover began thinning ? perhaps now the decreasing flux of heat was preventing further cloud formation.  In the shadow of the trees, the pinhole gaps began to take on the appearance of multiple crescents, and shadows began to sharpen perpendicular to the direction of the remaining crescent of sunlight.

By 2pm, eleven minutes before totality, things were really cooling down.  The light thinned and silvered, lending an oddly wintry feel to the tropical surroundings.  The orioles began to fly around skittishly, seeking a roost.  Now the sky was almost completely clear, so despite the cues for twilight, the entire horizon remained resolutely blue.  Final checks were made to equipment settings ? we were going to see the eclipse!
The final countdown to totality was thrilling.  The skylight dimmed perceptibly before our eyes ? Venus popped into sight, as if by magic, low to the west.  Now the crescent of remaining sunlight was beginning to break up as the serrated edge of the moon bit into the last uncovered edge of the Sun?s photosphere.

The lines of light dwindled to beads, and flickered out relentlessly one by one.  I looked away and out to sea.  The sky to the west darkened to near night and the wall of darkness rose upwards and towards us.  The last brilliant bead flicked out and totality was under way.  Above us was a jet black disk surrounded by the gorgeous soft white glow of the solar corona.
I rattled off a quick series of photographs, then switched to observing through my binoculars.  The corona was four?horned, with streamers flowing between the pairs of horns.  There was one bright red prominence, with hints of several others.  Mercury and Jupiter shone bright within a few solar diameters of the eclipsed Sun.

The horizon was a dull deep blue in all directions, confirming the circular shape of the moon?s shadow.  The audience were animated, emitting whoops of joy and expressions of glee.  The blustery offshore breeze had dropped completely, so that the only other sounds were of the frantic clicking of cameras.
?Three minutes* someone yelled, and I prepared for a final batch of photographs.  One more run through the exposure settings in preparation for the end of totality; then the pink glow of the chromosphere appeared on the lower limb.  And then the end of totality ? a beautiful, persistent, diamond ring of light on the pearly ring of the corona, as first of the Sun?s rays found their way through a valley on the lunar rim.  For a few hushed seconds the photographers snapped and snapped and snapped ? then as the beads began to reappear and the skylight level rose, a round of jubilant applause echoed round the bay.

Those of us with our wits still intact turned round to watch the shadow sweeping away to the north east.  I looked down to my feet and to my immense delight saw shadow bands rippling across the sand ? alternate light and dark patches, perhaps 20cm apart, flitting along the beach at running speed, seemingly in pursuit of the Moon?s shadow.  Shadow bands are caused by atmospheric turbulence causing rippling of the Sun?s first light, and the narrowness of the banding suggested a very turbulent layer somewhere above us ? probably the one our incoming plane had shuddered through on the way in.

Dedicated observers continued to photograph the outgoing partial phases of the eclipse, recording the re-appearance of sunspots as the Moon?s disk moved on.  This observer went for another swim before enjoying several celebratory beers.  As we swapped stories and drank toasts, a flying boat from the north made a low pass across the bay, and a cruise ship appeared from beyond the headland on its way south.  And for one party, aboard the plushest of the yachts in the bay, celebrations were only beginning.  Minutes after the end of totality, the strains of the wedding march rang out across Knip Bay, to applause from the shore.  We hope one lucky lady saw her third diamond ring of the day!

The MIRA Catalogue
By Vaughan Cooper and Ivor Clarke

Many years ago, during a cleanout of the observatory on the Coventry Technical College roof, a rather interesting item was uncovered. ?A Catalogue of I85 Celestial Objects suitable for a Two-Inch Object Glass Astronomical Telescope!* had been diligently compiled, from observation, by a past member of the Society.  The format is ingenious.  A little 1919 edition of Maunder?s ?The Stars - and how to identify them*, has the catalogue entries and remarks pasted onto the pages facing the constellation charts - but these may be lifted so that the text underneath can still be read.

Who compiled this very useful list (of double stars mainly) is not certain, but it was obviously done a long time ago.  A pencil note indicates the year 1926.  Whoever it was who compiled this list originally must have had an interest in mainly double stars only as many nebula and star clusters have not been listed which are well within range of a small 2* refractor telescope.  At any rate, it is high time that the catalogue saw the light of day once more again.  It was started off in MIRA number 4 (September 1984) and continued up to issue number 28, May 1990.  So with the help of Vaughan Cooper (who was the editor of MIRA for most of these listings), here is the listing of all of the catalogue we have at present, brought up-to-date and corrected with Vaughan?s help.

As most of the list contains double stars which by their very nature are revolving around each other, so can move position and distance quite a lot in the intervening years in some cases, Vaughan has corrected the separation and PA (Position Angle, measured in degrees from north via east, south and west) where ever possible to give modern figures.  I hope this new improved list will provide an ongoing project for someone to re-observe.

We start with the prominent Summer constellation of Lyra.  Exact positions may be easily looked up in any good star atlas such as Phillips, Sky Atlas 2000 or Norton?s 2000.0.  Editors notes are in brackets, these include Vaughan Cooper, Rob Moseley, Richard Barrett and Ivor Clarke .

Cat. No. and Constellation

LYRA

001 a Alpha,  (Vega)  mags. 1 & 10; sep. 60*.  (A severe test to start with!   Distance increasing, the companion is hard to see against the blaze of the primary.  A 3* shows many other stars in a low power field.)

002 b Beta,  mags. 4, 7, 8 & 11; seps. 45*, 65*, 85*;  PA?s 150°, 320°, 20°.  (It is interesting that the author has included two fainter stars in this system to form a wide quadruple. Webb does not mention them.  Can anyone confirm?  The bright star is an eclipsing binary, mag. 3·4 - 4·4, period 12·9 days.)

003 e Epsilon  ?Double Double*,  mags. 5 & 6, 5 & 6; seps. 2?, 3*.  (The two pairs are separated by 208*.  Some can see this with the naked eye.  Splitting the two close pairs is a stiff test for a 2* inch.)

004 z Zeta,  mags. 4 & 6; sep. 44*,  PA 150°. Colours topaz and green.  (Most star colours from this time contain strange colours, tints and tones which bare no resemblance to any type of star known today.  I suspect that what a lot of old observers were seeing was poor chromatic correction in their ?scopes and eyepieces.)

005 h Eta,  mags. 4 & 8; sep. 28*,  PA 85°.  A fine field containing another double.  (A wide separation easily visible in small telescopes.)

006 q Theta,  mags. 4 & 9; sep. 101*,  PA 70°.  Yellow and blue.

007 M57  ?The Ring Nebula*.  (Quite easy to find, lying a third the way between b Beta and g Gamma. Difficult in a 2 inch though.)
 Note the field around d Delta.

GEMINI

008 a Alpha  (Castor)  mags. 2 & 3, both white.  (When the catalogue was compiled the separation was 6*.  It is now 2·51* and slowly widening once more.  Technically it is beyond a 2* at present.  A good test for a 3* though.  This is the brightest binary pair in the northern hemisphere and will be at their widest, 6·5*, in approx. 60 years time.)

009 z Zeta,  mags. 3 & 7; sep. 90*,  PA 360°.  Yellow & purple.  ((Purple???)  z Zeta is both a variable star and a binocular double.  A yellow supergiant star of the Cepheid class fluctuating between mags. 3·7 and 4·1 every 10·2 days.  Binoculars or a small scope reveals a wide 8th mag. companion which is unrelated.)

010 e Epsilon,  mags. 3 & 9; sep. 110*,  PA 94°.

011  d Delta,  mags. 3 & 8; sep. 7*,  PA 197°.  Yellow & purple.  (Delicate object with a 3* scope, at 59 light years away with a 1200 year orbit.)

012 l Lambda,   mags. 3 & 10; sep. 10*,  PA 31°.  Colours green & blue.  (A good light test for a 3* scope)

013 b Beta,  (Pollux, mag. 1·16),  Note its rosy-orange colour.

014 M35,  A fine cluster near h Eta.
 Note the field around  h Eta.  g Gamma has a remarkable array of stars round it.

As Spring  progresses we see the constellation of Bootes, the Herdsman, rising steadily earlier in the Eastern sky.  It contains the magnificent Arcturus, the brightest star in the Northern hemisphere - so bright that Schmidt once saw it with the naked eye 24 minutes before sunset!

BOOTES

015 e Epsilon, mags. 3 & 6; sep. 3*,  PA 326°.  Orange & green.  (A gorgeous double, Struve?s ?Pulcherrima*.  Well seen with John Graham?s 3* refractor, xI56.  Separation slowly increasing.)

016 p Pi,  mags. 4 & 6; sep. 6*,  PA 99°.  Both white.  (Separation slowly increasing.)

017 i Iota,  mags. 4 & 7; sep. 38*,  PA 33°.  Yellow and white.  (In an attractive field.)

018 k Kappa,  mags. 5 & 8; sep. 12*,  PA 237°.  White and blue.  (Attractive contrast.)

019 d Delta,  mags. 3 & 8; sep. 110*,  PA 75°.  Yellow and blue.  (Visible in steady binoculars.)

020 m Mu,  mags. 4 & 7; sep. 108*,  PA 172°.  (Another binocular double)

021 Struve 1850,  mags. 6 & 7; sep. 26*,  PA 262°.  Yellow & blue.

022 Arcturus,  (mag. ?0·06).  Fine orange colour.  Lilac companion?  (The last entry is intriguing, Arcturus is not a double and the entry must refer to a field star at some distance.  What do you make of it?)

HERCULES

Hercules is a distinctive configuration well placed in the evening sky during Summer.  It occupies most of the area between Arcturus and Vega, and contains many fine coloured doubles - and a very famous globular cluster M13.

023 a Alpha,  mags. 3 & 6; sep. 5*,  PA 118°.  Orange & green.  (?Ras Algethi* a glorious colour contrast.  The orange/red primary is variable.)

024 g Gamma,  mags. 3 & 9; sep. 38*,  PA 242°.  White & lilac.

025 d Delta,  mags. 3 & 8; sep. 19*,  PA 175°.  Green & purple.  (These colours can?t exist on stars!)

026 z Zeta,  mags. 3 & 6.  (This is an odd inclusion - as it is well beyond a 2 inch telescope.  A fast moving binary with a period of only 30 years and a maximum sep. of 1·6*.  At the moment it is 1·4* and widening.  A stiff test for a 4 inch.)

027 k Kappa,  mags. 5 & 7; sep. 31*.  PA 10°.  Yellow & pink. (Pink?  In a fine field.)

028 r Rho,  mags. 4 & 6; sep. 4*,  PA 309°.  Green.  (A fine object.  Webb describes the companion as also greenish.)

029 m Mu,  mags. 4 & 9; sep. 30*,  PA 241°.  (The companion is a very rapid close binary - revolving in just 18 years!)

030 Cluster between z Zeta and h Eta.  (This is the famous M13 globular, the brightest globular cluster in Northern skies.  On a good night a 3 inch refractor at x100 will resolve its outer stars.)

The autumn groups of Androrneda and Aries are featured in this section.

ANDROMEDA

031 g Gamma, mags. 3 & 6; sep. 10*,  PA 62°.  Yellow & blue.  (Webb calls it ?One of the most beautiful pairs in the heavens.*  Discovered by Mayer in 1788)

032 p Pi,  mags. 4 & 8; sep. 36*,  PA 173°.  Yellow & blue.

033 M31,  The Great Galaxy.  (Visible to the naked eye, use a very low power on a moonless night.)

ARIES

034 g Gamma,  mags. 4 & 4; sep. 8*,  PA 360°.  White & yellow.  (Most observers see both stars of this fine equal pair as pure white - although Webb gives ?Violet-white & yellow-white*.)

035 l Lambda,  mags. 5 & 6; sep. 37*,  PA 45°.  White & lilac.

036 a Alpha,  a fine yellow star.  (Called Hamal, it is mag. 2)
A look at the Zodiacal constellations of Leo, Cancer, Virgo and
Libra.

CANCER

037 i Iota,  mags. 4 & 6; sep. 30*,  PA 308°.  Both yellow.  (Some say beautiful contrast yellow and blue.)

038 Praesope cluster.  (Magnificent ?Beehive? cluster, very large, 1°, bright, naked eye cluster.)

LEO

039 g Gamma,  mags. 2 & 4; sep. 4*,  PA 118°. Orange & Green.  (A famous double, sep. and PA slowly increasing.  Difficult for a 2*.  Try to observe this star against a twilight sky as this helps the colours to stand out.)

040 t Tau,  mags. 5 & 7; sep. 95*,  PA 170°.  Lemon & blue.

041 54,  mags. 4 & 7; sep. 6*,  PA 102°.  (Both white.  PA increasing)

042 93,  mags. 5 & 8; sep. 74*,  PA 356°.

043 Regulus, mag. 1·3; star 176* away. ?Steeped in indigo.*  (PA 86°, quoted remark is not supported by observers today.  Regulus is a double with a mag. 10·8 companion.)

044 R Leonis.   (One of brightest ?Mira?  type variables, mags. 5·9 at max. to 10·1 at min. with a period of 370 days approx.)

VIRGO

045 g Gamma,  mags. 3·6 and 3·7; sep. 6*,  PA 150°.  Both yellow.  (A famous double, PA decreasing as well as distance between stars, period 171 years, so that this is now a difficult object even in larger telescopes.)

046 t Tau,  mags. 4 & 8; sep. 79*,  PA 290°.

047 q Theta,  mags. 4 & 9; sep. 7*,  PA 345°.  (White primary.  Test for a 3* scope)

LIBRA

048 i Iota,  mags. 4·5 & 9; sep. 57*,  PA 110°.

049 a Alpha,  mags. 2·8 & 5·2. Yellow & gray.  (Sep. 231*,  PA 314°, a wide pair.)

050 b Beta.  Note green colour.  (Mag. 2·61.  Is this is a mistake?  The green colour is apparent on the secondary of a Alpha, the binary listed above is some books.  There has always been great controversy over the existence of this green hue.  Only the observer themselves can decide whether it is there, but if it is a real effect then it is the only single star to appear green).

AURIGA

051 l Lambda,  mags. 5 & 9; sep. 121*,  PA 13°.

052 41,  mags. 5 & 6; sep. 8*,  PA 335°.  (Webb refers to the colours as tawny or violet.)

053 14,  mags. 5 & 7·5; sep. 14*, PA 225°.  (Cream and dull blue.)

CASSIOPEIA

054 a Alpha,  mags. 2 & 9; sep. 62*,  PA 280°

055 h Eta,  mags. 4 & 7; sep. 5*,  PA 200°.  White & purple.  (Long period binary.)

056 i Iota,  mags. 5 & 8; sep. 7*,  PA 112°.  (In lar