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| Nix, Pluto and Charon, enhanced image computed by Celestra 1.6.1 |
Just a few hours left to download the ebook version of our "Pluto &
Charon" pictorial volume from kdp and/or Amazon for free! The printed
edition, published in June 2016, is full-colour and US-letter-sized to
display the best images taken by the New Horizons spacecraft in all
their splendour. (No, I have no idea why the price in US-Dollars is so
much out of proportion in comparison to Pounds and Euros. Blame Amazon
for that, it's their odd calculation.)
"In this book its two authors have managed to present the intriguing
results of New Horizons’ Pluto flyby in a mode that non-professionals
will understand, without waiving appropriate scientific accuracy.
Pluto was discovered by Clyde Tombaugh in 1930 and stayed the only known
large object in the outer solar system for more than 60 years. Then,
since the 1990s, improved CCD technology helped track down more than a
thousand other objects in the ‘Kuiper Belt’. The size of some of them
came close to Pluto, and Eris, photographed in 2003 but escaping notice
till 2005, threatened even to replace it as the biggest object in the
Kuiper Belt. The result was a re-definition of the term ‘planet’ by the
general assembly of the International Astronomical Union, held in Prague
in summer 2006. Pluto is no longer called a planet since. From the
perspective of celestial mechanics, this decision may be reasonable and
logical because Pluto does something that a decent planet should not do:
It crosses the orbit of another planet. The large planet Neptune has
forced small Pluto and several hundred, recently discovered, smaller
bodies called plutinos into a 3:2 orbital resonance by its gravitational
force that avoids any collisions with Neptune.
Fortunately, half a
year had already passed since the launch of the New Horizons spacecraft
when the new definition of the term ‘planet’ was voted about. If Pluto
had not been a planet at that time any more, some overzealous
US-senators might have simply cancelled its construction to add the
money saved to their military budget. (This was what had indeed happened
to the Dawn spacecraft for some months.) In such a case, the wonderful
close-ups of this amazing world at the very edge of the solar system
would have escaped us.
With the findings of New Horizons in mind,
said new definition should be reconsidered. I am sure that the voting
would have had a different result if we had already known back then what
New Horizons has revealed to us about Pluto. The new definition is
based on celestial mechanics only and does not take Pluto’s
peculiarities into account that it has from the planetologist’s point of
view. It has more characteristics of a regular planet than the twice as
large inner planet Mercury: While Mercury is a grey orb whose surface
has primarily been shaped by impacts, New Horizons has shown us Pluto as
a body with a distinctive geology of its own from far away already.
There are diverse types of terrain present: mountainous areas alternate
with smooth plains of nitrogen glaciers in which water icebergs are
drifting about, driven to the edges of convection cells by up-welling
heat; their dark summits peak out like islands.
Unlike airless
Mercury, Pluto does have an atmosphere that does not simply become more
tenuous from inside out, but it is many-layered in the very meaning of
the word: images of Pluto‘s rim reveal several banks of haze at
different levels above ground. There must be some kind of weather as
well. As Pluto heads on to those parts of its orbit that are remote from
the sun, a part of its atmosphere will freeze out and precipitate on
its surface, only to thaw again when it is back to perihelion - 200
years later. And one of the images, scientists believe, even seems to
depict a cloud bank.
Moreover, Pluto has a complex satellite system
comprised of five moons, and their periods resonate with each other and
they are almost exact multiples of the revolutional period of the
biggest moon, Charon. Compare this to the fact that Mercury and Venus
have no moons at all, our Earth, one, Mars, two small ones, and among
the minor planets there are only systems with up to two moons known.
Even though Pluto may not be elevated to planet status again, our solar
system and the eight planets that are officially left will presumably
not represent the complete image yet. During the last few years, six
lesser bodies have been discovered far away whose perihelions (their
points of closest approach to the sun) are located far beyond Neptune
and the Kuiper Belt. And their orbits are close together in space, which
may perhaps not be explained by chance alone. These objects measure
less than 1,000 km in diameter, and therefore, they are certainly not
proper planets. But they cannot have developed out there, in empty
space. Something larger must have taken them so far out from the sun,
like Neptune has set the plutinos and other objects of the Kuiper Belt
on their courses.
Mike Brown, he who has initiated Pluto’s
demolition by discovering almost Pluto-sized Eris, supposes that a
planet may be lurking out there that has about 10 times the mass of the
Earth. Such a behemoth would certainly fit the new criteria for ‘proper’
planets, and Mike Brown has already assigned the unofficial name Planet
Nine to it. Based on the data of those six farthest bodies, an
approximate orbit of this still hypothetical planet can be also
computed. According to these values, it travels around the sun 700 times
as far out as Earth and 30 times as far out as Neptune, spending about
20,000 years on one revolution. But at which point of its orbit it might
be at the moment, that cannot be computed.
That this planet has
not been discovered yet should not struck anyone by surprise. Since the
brightness of a body decreases by the fourth power of its distance from
the sun, even an object as large as Neptune would be a million times
dimmer than that. Mike Brown is rather confident, however, that his
Planet Nine will be detected within the next 5 to 10 years by improved
sky survey programmes. Once it has been located, a spacecraft will
certainly be sent to this planet, and the two authors behind the Codex
Regius label are no doubt already standing ready to publish the results
of this flyby in a book. If NASA should take recent plans of a
laser-powered interstellar miniature probe serious, this might even
happen within our lifetime.
We have waited long enough for the Pluto flyby.
But … it has been worth waiting, that you will see on the following pages!"
Dr Rainer Riemann
Heidelberg, in June 2016
