A Celebration of Mercury

Planet Mercury has the reputation for being illusive.

Given good, clear skies and an uncluttered horizon, there is no excuse for missing the planet in twilight skies close to elongations. The current western elongation is a case in point.

Here in Orkney the opportunity to see Mercury with the unaided eye commenced from about November 15. Poor weather meant that my first glimpse of the planet was on the morning of the 19th. Abysmal weather conditions ensued until December 2, when a strand of clear sky low in the south-east made way for a splendid view of the planet.

I have always been a champion of Mercury. Its golden light is unique. Both Venus and Jupiter (most times) outshine Mercury. Mars too can appear brilliant and Saturn with its rings open can exceed Arcturus. But all these planets to the unaided eye seem not to differ in colour from the range in colours in the stars themselves, whereas I have yet to find a star that quite mimics Mercury.

The star which most closely appears to me to resemble Mercury's light is Pollux. But Pollux is one of the fainter stars of the first magnitude whereas Mercury, close to maximum elongations, is only exceeded in brilliance by Sirius and Canopus amongst the stars.

These observations of Mercury are of the essence for me. I commenced my career as an astronomer shortly after the ending of the Second World War with only my pair of eyes and a small opera glass.

Those were days of austerity in complete contrast to the wealth of equipment at modest prices available to the astronomy enthusiast today.

Likewise in those days in the field of publications and media coverage astronomy was very poorly represented. One has only to compare the current lavishly produced British Astronomical Association’s Journal with its predecessors of fifty years ago to understand my point.

And today there are magazines available on bookstalls, such as Astronomy Today and The Sky at Night, which would have been undreamed of in those early days.

But for all that, those starting off in astronomy today face problems from pollution of all kinds which might deter all but the most dedicated. Only twelve miles from London my father was able to take me on evening walks in mid-winter and to excite my enthusiasm by pointing to the star clouds of the Milky Way.

In my extensive library I have a small book called Guide to the Stars (Hector Macpherson, April 1945).

Macpherson writes: "So much for the utility of knowing the names of the various stars and constellations; but a knowledge of this kind is more than merely useful. No-one can enter into what may be called the spirit of astronomy without having an acquaintance, however slight, with the planets and stars individually."

And so I return to Mercury and let the poet pay tribute for me:

Mercury at dawn

I recall them saying to me, once, long ago,
how the planet Mercury shone golden at dawn.
Copernicus, it is said, never saw it,
hard to believe as I watch the golden planet
buoying through the cloud-driven dawn.

Lone messenger at dawn

Standing in the dawn silence,
Mercury's light, singularly and enduringly beautiful in the natural sky;
almost painful in his isolation, coming upon him thus,
through diligence, I feel a welcome intruder.

January the 1st 1998 - Mercury at dawn

All the naked-eye planets ranged before me across the diurnal sky:
sickled Venus and the sickled Moon - close (face to back),
Mars a little way off, thence Jupiter and Saturn,
then the long winter night through to dawn
with Mercury, solitary in Scorpio,
his golden light true gold in a golden dawn.

JV 4/12/06

Mercury's persistency

Dia. 1 The sky looking SE at 07h 30m UT on the morning of November 23. The path of Mercury is shown for the succeeding 10 days.

Dia. 2  Looking SE at 08h 00m UT on the morning of December 9. By the same time the following morning the three planets Mercury, Mars and Jupiter, will lie within a circle of a little under 1 arc degree diameter.

Mercury's present elongation provides an opportunity to follow the illusive planet with the unaided eye for a period of around one month from mid-November to mid-December.

Dia 1 shows the path of Mercury from 23 November to 3 December.

There is the added interest that between December 9 and 12 Mercury will appear in close company with Mars and Jupiter. By then the planets will be low in a strongly twilit sky.

However, Jupiter will be a useful guide owing to its greater brightness, approximately twice that of Mercury. Mars at 1.5 magnitude, on the other hand, is close to its faintest.

Binoculars will greatly assist the observation.

From 27 November, for three weeks, Mercury maintains effectively the same magnitude at around -0.6. Thereafter it brightens a little but will be too close to the Sun for observation using smaller instruments.

JV 22/11/06