STARE at the sky at night and millions of questions will just pour into your
head. Arthur Upgren has some answers for you. Go with him on a trip through the
past in his intriguing piece on “What Ayala saw”, for example. Ayala is the
heroine of a famous children’s book, assumed to have lived more than 10 000
years ago. With her, you’ll discover why the night sky then was slightly but
perceptibly different from today’s.

His subtitle is A Naked-Eye Guide to the Sky, its Science and its
Lore, but as Ayala shows, this isn’t the whole of his book. He considers
thorny problems from the cause of the seasons to the chances of a dangerous
collision with a meteorite, the last return of Halley’s Comet, the significance
of Stonehenge and the possibility of life elsewhere. He even launches into a
discussion of the Age of Aquarius (due to begin around AD 2614), rightly
concluding that “people will continue to believe what they want to believe,
regardless of fact”.

The purely naked-eye section takes you through the four seasons of the year
with simple maps of the main constellations on view. (His text is geared to
observers in the northern hemisphere, particularly Americans.) The maps are
adequate and certainly look attractive, though I think a few more detailed
charts would have been useful, particularly one of the Moon. After all, the main
lunar features can be seen easily enough without any optical aid.

This informative and enjoyable book will certainly appeal both to beginners
and to those who have at least a working knowledge of astronomy. My only serious
criticism is that the illustrations are rather sparse.

IN 1930, Clyde Tombaugh, the young amateur astronomer who had been engaged by
the Lowell Observatory in Arizona, discovered the ninth planet, Pluto. Fifty
years later, a Pluto symposium was held at New Mexico State University, Las
Cruces, where Tombaugh was by then emeritus professor. It was over in a day: by
1981 almost everything known about Pluto could be summarised very briefly
indeed.

Subsequently Tombaugh paid me the great honour of inviting me to
collaborate with him in writing the Pluto book. It duly appeared, but was a
decidedly slim volume.

Things have changed beyond all recognition. We now know a great deal about
Pluto, even if much remains to be learnt, and a new book written at a popular
level has been long overdue. It has been provided by Alan Stern and Jacqueline
Mitton, who have excelled in the task.

Pluto and its companion Charon make a strange pair. They are unlike any other
planets in the Solar System, and it is questionable whether they merit true
planetary status. Pluto is not only smaller than our Moon, but smaller than
Neptune’s principal satellite, Triton. Normally it is the farthest planet,
although it has an eccentric orbit and between 1979 and 1999 is actually closer
to the Sun than Neptune. It takes about 248 years to complete one orbit, so it
was discovered only a quarter of a Plutonian year ago. It is faint—around
magnitude 14—and it is only thanks to the Hubble Space Telescope that we
have been able to see any details on its tiny disc. After all, Pluto’s apparent
diameter is only about 0.1 of a second of arc, and as yet no space probe has
been able to pass anywhere near it. The authors are well qualified. Stern is a
principal investigator in NASA’s planetary research programme, while Mitton is a
qualified astronomer who now concentrates mainly on popular writing. Most of the
present book was written by Stern, and is very American in style—and
perhaps, though I do not mean this as a criticism, the book may prove rather too
American to please some British readers.

Following a general introduction, the discovery of Pluto is described in
detail. It’s an interesting story: Pluto’s distance from the Sun had been
predicted fairly accurately by Percival Lowell (of Martian canal fame), although
in view of Pluto’s tiny mass this may have been purely fortuitous. Next, we come
to the first firm fact: the rotation period of the planet is 6 days and 9 hours,
a figure initially derived from studies of variations in magnitude and Pioneer’s
spectroscopic investigations. There is then a long and excellent section on the
wealth of information gathered when Pluto and Charon took it in turns to obscure
each other in the late 1980s.

But what of Pluto and Charon themselves? They are linked by the fact that
Charon’s orbital period is the same as Pluto’s rotational period. To a Plutonian
observer, Charon would remain fixed in the sky—a situation unique in the
Solar System. Charon, which was possibly formed by a giant impact, is much the
smaller and darker of the two. Charon also has a different surface, though both
worlds are apparently coated with ices. Pluto has an extensive, though very
tenuous, atmosphere, which may prove to be impermanent. But so far as we know,
Charon has none. The pair came closest to the Sun, their perihelion, in 1989,
and are now moving towards an aphelion in the 22nd century. As they draw away,
their surface temperatures drop. It is likely that Pluto’s atmosphere will
condense out onto the surface within a few decades. Presumably its present
atmosphere is made up chiefly of nitrogen, which is not at all
surprising—Triton, Neptune’s main attendant, also has a thin nitrogen
atmosphere.

For many years, Pluto and Charon seemed to be alone in these remote regions,
but we now know that this is not the case. In recent years, many small planetary
or asteroidal-sized bodies have been found to be roaming near them. The first,
now known officially as 1992QB1, was found in 1992 by David Jewitt and Jane Luu,
and seems to be between 15 and 250 kilometres in diameter. (Jewitt and Luu gave
it the unofficial name of “Smiley”, after a character in a novel by John Le
Carré, but the name cannot be accepted by the International Astronomical
Union because there is already an asteroid of that name honouring a 19th-century
astronomer.) Other similar bodies have since been discovered, and everyone now
agrees that there is a whole swarm of them. None is anything like as large as
Pluto, or even Charon, but we cannot yet be confident that there are no more
Pluto-sized objects beyond the orbit of Neptune. Pluto may not be unique after
all.

Unfortunately our knowledge is still limited, and even Hubble can do little
more than show vague dark and brighter patches. Our map of Pluto is still
rudimentary, though there is already discussion about naming some of the
features. (As a member of the IAU Nomenclature Committee, I have suggested using
the names of underworld deities, though whether this will be accepted remains to
be seen.) What we really need is a new probe aimed specifically at Pluto. There
may not be too much time to spare before Pluto’s atmosphere condenses out and
makes the whole situation more difficult.

Plans have been proposed, and Stern has himself been involved. It is hoped to
launch a “Pluto Express”—a very lightweight mission that would therefore
be cheap by astronautical standards. It could carry instruments that could give
us information about the surface details of both Pluto and Charon, and also
about their surface ices. Is Pluto at all like Triton, from where Voyager has
sent back pictures of pink nitrogen “snow” together with active geysers? Or is
Pluto totally inert?

The fate of the Pluto Express rests with NASA, and ultimately upon finances.
We must hope that it will be approved, because its information would be
fascinating by any standards.

Pluto which shines modestly as a star-like point of the 14th magnitude. At
present it lies in the constellation of Ophiuchus, and any well-equipped amateur
can locate it. The more we find out about it, the more intriguing it becomes,
and Stern and Mitton have filled a notable gap in the literature. This excellent
book should be upon the shelf of every astronomical library.

THIS is an unusual book. It deals with the search for life on Mars—a topic very much in our minds at the present moment—but in a controversial way. It sets out to show that one of the experiments carried to Mars by the Viking space craft in the 1970s did indeed detect signs of lower lifeforms, but that NASA prevented the findings from being made public, and even went so far as to falsify some of the results. Barry DiGregorio is a science writer, but the fact that a chapter has been contributed by Gilbert Levin, principal scientific investigator of the “Labelled Release” project, suggests that Mars: The Living Planet should be taken seriously.

The experiment looked for evidence of microorganisms in the soil of Mars by placing a drop of radioactive nutrient on the soil and measuring the gas coming out of it. The Labelled Release experiment was designed and built by Levin; it was the only experiment on Viking that satisfied all the mission criteria for the discovery of life on Mars.

But did it really prove that microorganisms were present? Opinions differed, and many other members of the Viking team believed that the reactions detected were purely chemical.

DiGregorio is in no doubt that there was deliberate concealment, and that attempts were made to show that Mars is sterile. For example, he cites the case of the “blue sky photograph”, the first image returned by the Viking lander direct from the Martian surface. “The image showed an Arizona-type landscape,” he writes, “blue sky, brownish-red desert soil, and grey-black rocks with greenish patches . . . Two hours after the first colour image appeared on the monitors, a technician abruptly changed the image from the light-blue sky and Arizona-like landscape to a uniform orange-red sky and landscape”.

This sounds rather strange, to put it mildly, and throughout the book there are other claims that Levin’s work was distorted and discredited. DiGregorio suggests various reasons for this: the discovery of Martian life would give offence to religious groups, and it might have an adverse effect on NASA funding. The latter seems unlikely—the recent furore about the supposed evidence for life in a Martian meteorite found in Antarctica has had the reverse effect.

DiGregorio writes well, and has clearly done a great deal of research. There is an excellent list of references, and nothing touching on the usual conspiracy-theory nonsense involving astrology, flying saucers and little green men. (Mercifully, there is no mention of the “face on Mars”).

He takes great care to emphasise the need to quarantine any samples brought back from Mars. Certainly, caution is required, but he does seem to be somewhat alarmist in claiming that NASA took unacceptable risks in allowing astronauts to expose themselves briefly to the open air after returning from the Moon.

It may well be that the controversy will be settled by the Sojourner rover now operating on Mars, and sending back images of a red landscape and a pink sky. It is surely too much to suggest that these pictures have also been falsified before being released.

It is probably fair to say that there is much in this book which is worth reading. But the conspiracy-theory theme should be taken with a rather large grain of cosmic salt.

“SURELY one of the most marvellous feats of the 20th century would be the
firm proof that life exists on another planet. All the projected space flights
and the high costs of developments would be fully justified if they were able to
establish the existence of life on either Mars or Venus. In that case, the
thesis that life develops spontaneously when the conditions are favourable would
be far more firmly established, and our whole view of the problem of the origin
of life would be confirmed.”

So wrote Harold Urey and Stanley Miller, chemists working on primordial
atmospheres. Their words, written in 1959, are still relevant. We still cannot
decide whether life is widespread in the Universe, as some scientists believe,
or our own Earth is unique. Steven Dick, astronomer and historian at the US
Naval Observatory in Washington DC, provides a summary of the problem in The
Biological Universe—and has done so in brilliant fashion.

After a brief introduction, he examines early views of the Universe, theories
of planetary evolution and efforts to trace life in the Solar System. He deals
expertly with the famous (or infamous) Martian canals and with our pre-Space Age
attempts to unravel the mysteries of Venus, and describes the results of the
various probes, notably the Viking landings on Mars. Surprisingly, he fails to
mention the Magellan spacecraft that has given us our best information about
Venus.

Next Dick turns to the possibility of planets circling other stars. He
stresses that, despite false alarms in the past, we now have strong evidence
that such planets exist, even though we await final proof. He then surveys
science fiction, from Lucian’s Moon-creatures of the 2nd century AD through
Jules Verne and H. G. Wells to Arthur C. Clarke. The storytellers have sometimes
turned out to be excellent prophets. There is also a particularly good chapter
on UFOs.

And then we come to the origin and evolution of life and the central question
of whether what has happened on Earth can also happen elsewhere. This leads us
to the possibilities of communicating with other intelligences. I found the
section dealing with attempts to signal to Mars, and to pick up Martian radio
messages, vastly entertaining. Dick deals with Ozma, the first serious
programme, before going on to cover the ill-fated American SETI programme, which
began in 1992 with such enthusiasm only to be abruptly cancelled by Congress a
year later as part of a cost-cutting campaign. (If Congress had decided to
cancel just one nuclear submarine, SETI could have been funded for decades.) The
last part of the book pulls together the scientific disciplines involved. Dick
even ventures into the sensitive area of how religion would be affected by
contact with another race.

The Biological Universe is a mine of information, grippingly well
written. The references are exhaustive, so the book will be of equal value to
the serious researcher. Errors and misprints are conspicuous only by their
absence.

Dick was very unlucky to have completed the book just before several highly
relevant developments were announced. Planets of other stars, such as the body
associated with 51 Pegasi, have been identified, but Dick could only briefly
mention this. And, of course, there has been the startling claim last month that
a meteorite found in Antarctica has come from Mars, and contains evidence of
past primitive Martian life. Many people (myself included) have marked
reservations about these claims, but their importance cannot be doubted. They
came to hand too late to be included, so we will certainly need another edition
of The Biological Universe in the near future. Despite this accident of
timing, this is the best book on extraterrestrial life I have ever read.

This is a refreshing book. Unlike most books dealing with the planets
it does not concentrate largely on the space probe results. Indeed, space
research is discussed relatively briefly, and the book focuses almost entirely
upon what can be seen with Earth-based telescopes, particularly those operated
by amateurs. Fred Price is professor of biology and biochemistry at the
State University College in Buffalo, New York, and because he is not a professional
astronomer he has obvious sympathy with the ‘backyard enthusiast’. It is
also clear that he is an active observer.

The Planet Observer’s Handbook begins with a general description of
the Solar System, followed by an account of the celestial sphere and a particularly
good chapter on telescopes and accessories – the diagrams here are among
the best I have seen for a long time. After dealing with the problems of
seeing, Price discusses the planets one by one. Each chapter includes a
section on the history of observation, then the results from the space missions
and methods of observation using telescopes of smaller or moderate aperture.
The book ends with sections on map and planisphere construction, photography
and more advanced instrumentation.

You might wonder why observations carried out from Earth are still of
value when no telescope can hope to see as much detail as a Mariner or
a Voyager. But as Price points out, there are very few spacecraft monitoring
the planets at present, and any exceptional phenomena are quite likely to
be discovered by amateur observers rather than professionals, who are justifiably
far more concerned with objects far beyond the Solar System. There is a
tremendous amount of useful information, and helpful advice for casual observers,
and for those who are anxious to contribute information of real scientific
value.

Inevitably, there are points of criticism. In some cases the text is
not as up to date as you might expect and in the chapters on Jupiter and
Saturn particularly, it seems that too much attention is paid to older observations
carried out by telescopes that are fairly obviously inadequate. In the
Jupiter section, much of the material relates to pre-Second World War observations.
Price does not seem to appreciate that the South Tropical Disturbance, one
of the most prominent surface features of Jupiter earlier this century,
has not been seen since 1940 and has almost certainly vanished for good.
Many of the planetary drawings are excellent, notably those by the British
amateur Richard M. Baum, but others are of lower standard, and some of
the amateur photographs are poor.

There must also be differences of opinion. For example, the author does
not discount entirely the ‘spoke system’ on Venus, about which my own sceptism
is profound; neither does it seem at all likely that details on Uranus or
Neptune are within the range of average telescopes. I have studied both
with the Mount Wilson 60-inch reflector without seeing any details at all.
Frankly I doubt whether even a much superior observer could have done
better.

However, the main weakness is in the proof reading. For instance, on
page 80 Price refers to ‘the late A. Dolfuss’. I am delighted to report
that the celebrated observer Audouin Dollfus is still very much alive and
well. The accepted symbol for declination is d not b; Pluto does have a
satellite; and there was no transit of Venus in 1878. In some cases the
diagrams have not been checked, for example, the sizes of the asteroids
Juno and Vesta have been interchanged in one. But these are minor criticisms.
The reference material is generous: each chapter ends with a bibliography
listing not only specialist books but also relevant articles from astronomical
journals and periodicals.

Price has put a great deal of effort into the book, and it must be regarded
as a definite success. It will be valuable both to the beginner and to the
serious planetary observer. I strongly recommend it.

Patrick Moore has specialised in lunar and planetary observation since
1957.