Jupiter's four major satellites.

Fig. 1 Jupiter, April 16 at 20h 52m GMT

Fig. 2 Jupiter, April 23 at 21h 55m GMT

The number of observable transits by the four major satellites across the planet's disc has been fewer this year than last. However, two interesting configurations involving Europa and Io occur when both satellites transit close to one another.

As a result, on April 16 from 18h 57m to 20h 05m, and on April 23 between 21h 23m and 21h 53m, Jupiter will appear in small telescopes to have just two satellites since neither Europa nor Io will be seen.

Fig. 1 April 16: shows Jupiter with the shadows of Io and Europa, together with Europa itself, on the disc. (Europa may be seen against the dark band with larger telescopes.)

Fig. 2 April 23: shows Europa and the shadow of Io, with Io just leaving the disc. (The shadow of Europa will appear on the disc at 23h 27m, by which time the shadow of Io will have departed.)

Note: Both illustrations are diagrammatic and include the great red spot.

JV
April 2004

Which Universe?*

Figure 1: Looking West at 22h 05m GMT April 19 2004, Rousay. Mars is a little to the left of the brilliant Venus; Saturn more to the left and a little higher (below Castor and Pollux). Capella is the bright star above Venus. A 15 sec. exposure, 24mm f/2.8 ISO 400. John Vetterlein.

I sometimes receive a request asking for my views on current cosmology theories; not a torrent of requests, I admit, but more than I can hope to reply to personally since each individual raises slightly different questions. The best I can do is to offer the following brief explanation on my present outlook.

I have difficulty in regarding the universe, or a universe, as an entity - there is no beginning, there is no end, there is only what is happening. Fortunately I have a reasonable mathematical ability to enable me to hold my own with some at least of contemporary cosmological research. I am quite able to use mathematics to show that where a rigorous philosophical argument may offer a single answer to a problem, mathematics can offer two or more answers to the same problem.

In regard to the so-called "big bang" theory, I hold a similar view to that expressed years ago by Bertrand Russell in his ABC of Relativity**: "Those people who think it did occur (big bang) are inclined to refer to the highly condensed state as 'the beginning of the universe' or 'the time when the universe was created' or something of that kind. These phrases mean no more than 'the earliest time about which there is ever likely to be any scientific information,' and it is better to avoid them, because they carry undesirable metaphysical implications."

In the late 60s I gave a series of 12 lectures on cosmology for undergraduate, final year, students of engineering. At the first lecture I asked the group (about twenty students) what knowledge of astronomy any of them had; only one admitted to an interest. At the end of the lecture the students wanted to know when we would be getting round to the cosmological bit - 'you know, the origin of the universe and all that stuff?' 'Be patient,' I said, 'we have to learn to swim before we can drown.' The answer was taken in good part but I had my doubts whether any understood what I was driving at.

String theory is the present fashion and, in my humble opinion, the best this can achieve will be to tie us into further knots. All such theories are no more and no less than exercises in human ingenuity.

As to "a theory of everything"? Pull the other one.

* From the paper (1998) of the same title by the writer.

**ABC of Relativity, Third Edition 1969, page 108.

JV
March 2004