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NOVEMBER 2012 ISSUE
Planetary Geology
A three part special continued… Planet formation
Pages 10-11
Andromeda
Pages 8-9
Pages 4-5
Planet Killers
Editor: Chloe Partridge
Copy Editor: Martin Griffiths
Contributors: Emma Quinlan, Terence Murphy
Columnists: Phill Wallace, Martin Griffiths
If you would like to contribute in any way, either by sending us
your Faulkes images, or perhaps even writing an article , then
get in touch, we would love to hear from you.
Editorial Contacts :
IMAGE REFERENCES:
PG 1. Folded foliation in a metamorphic rock —en.wikipedia.org
PG 4-5. Earths— www.freewebs.com, Death Star— en.wikipedia.org, Giant Space Raygun.- static.ddmcdn.com
PG 6-7. Mica Schists — www.geolsoc.org.uk, Anticline at Pembrokeshire— www.geograph.org.uk
PG 8-9. All images Martin Griffiths, Sky Map — Heavensabove.com
Pg 10-11. Planet formation— www.topnews.in
PG 12. Richard Dawkins— www.poetsgraves.co.uk
EDITORIAL
This months magazine brings with it the continuation of
our 3 part Planetary Geology special — this month on
Metamorphic rocks. As expected we have another
excellent end of the world extravaganza by Phil Wallace
and a detailed account of this months night sky by Mar-
tin Griffiths.
Terrence Murphy also talks s through planetary system
formations and the dilemma scientist are facing as
they have to re-think the old models!
Have another good month!
N O V E M B E R 2 0 1 2 I S S U E
GL
MA
OR
GA
N
AS
TR
ON
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Y
C O S M O L O G I C A L N E W S
8 - 9 . T H E N I G H T S K Y I N N O V E M B E R
T H E L E O N I D M E T E O R S H O W E R M A K E S A G O O D S H O W O N T H E 1 7 T H W I T H A T H R E E D A Y M O O N A L R E A D Y S E T A T T H E B E S T
P O I N T O F T H E S H O W E R . S K Y C H A R T S , M O O N A N D P L A N E T S F O R
N O V E M B E R .
4 - 5 . M A R C H O F T H E P L A N E T K I L L E R S
T H E W E A P O N S O F S C I F I A R E A L W A Y S I M P R E S S I V E , B U T T H E
B I G G U N S A R E T H E M O S T E X C I T I N G .
6 - 7 . R O C K T Y P E S – M E T A M O R P H I C
M E T A M O R P H I C R O C K S A R E C O M P L E X A N D R A T H E R U N I Q U E T O E A R T H . O N L Y T H R O U G H C O N T I N E N T A L U P L I F T I N G A N D
E R O S I O N A L P R O C E S S E S D O W E S E E T H E S E R O C K T Y P E S A T T H E
S U R F A C E . W H I C H T E R R E S T R I A L P L A N E T S C O U L D P O S S E S S T H E S E B E A U T I F U L R O C K S ? T H E R O C K T Y P E J O U R N E Y
C O N T I N U E S …
1 0 - 1 1 . M A N Y F A C E T E D P L A N E T
F O R M A T I O N
N E W P L A N E T S H A V E B E E N A N N O U N C E D T H I C K A N D F A S T
A N D P L A N E T A R Y S C I E N T I S T S H A V E H A D T O R A D I C A L L Y R E T H I N K T H E F O R M A T I O N A N D D E V E L O P M E N T O F P L A N E T A R Y
S Y S T E M S A F T E R R E A L I S I N G T H A T T H E S O L A R S Y S T E M I S N O T A
G O O D G U I D E T O P L A N E T A R Y F O R M A T I O N E L S E W H E R E .
6 - 7
4 - 5
8 - 9
1 0 – 1 1 .
Page 4 C O S M O L O G I C A L N E W S
March of the
Planet Killers
We sci fi fans love our weapons, be they
blasters or phasers or plasma rifles or
shuriken catapults or fusion carbines. Lots of
fancy guns with fancy capabilities turn up in
science fiction, all of them far more deadly than
weapons we build now. Of course, since we’re
human and bigger is better we find nukes and
other WMD’s the most interesting. Weapons that
wipe out whole populations and level great
cities evoke a rather disturbing interest in our
hearts.
So here’s the problem. You can’t have nukes be
the most powerful weapon in sci fi. After all, if
you’re flying around in starships that can cross
hundreds of light years, you must have more
powerful guns than us ordinary real life
humans. In sci fi, the nuclear arsenal is not the
civilisation ending threat it is to the real world.
Worse, since nukes actually exist and have
known limitations, it’s hard to use them in a
story without some boring nerd pointing out
that you’ve got the blast-effect pattern wrong
(yes, that does come from personal
experience). Sci fi fans are accustomed to the
idea of nukes; they want something more.
Something more? Sounds absurd doesn’t it.
Something worse than a nuclear arsenal. Well,
since a nuclear arsenal ends the world with ten
thousand small bombs, what about a weapon
that ends the world with a single act? Enter the
Planet Killer.
A planet killer is, as you would imagine,
something that kills planets; renders them
lifeless hunks of rock. Most of the time this is
due to extreme surface damage but some
weapons go further; they turn a planet to
rubble. These are planet destroyers and evoke
an even more primal fear than regular planet
killers do. After all, we all know that humans are
temporary, but if something is capable of
shattering the very planet upon which we live
(rather than just scouring it of life) it is
terrifying indeed.
Some civilisations go even further and build
starkiller weapons. Blowing up a whole solar
system is rather excessive if there is only one
planet you really aren’t fond of, but these things
happen. So let’s look at a sample of notable
planet killers:
Giant Space Raygun. Avoid if possible
Page 5 N O V E M B E R 2 0 1 2 I S S U E
The Death Star: Star War’s famous huge
spherical space station. The Death Star (and
its successor) mounts a single huge
superlaser that carries enough energy to
completely destroy an Earth-like planet in a
single shot. And when I say destroy I mean
“vaporise most of it and scatter the rest.”
To give an idea of how powerful this weapon
is, the minimum energy needed to scatter an
Earth-sized mass is 1032 Joules. That’s a big
number, but that would mean the mass
would take over ten minutes to double in
volume. To create the Death Star like effect,
you need something more like 1038 Joules.
Which is, incidentally, the same amount of
energy produced by our sun in eight
thousand years. Big boom.
The Hand of Omega: An ancient and
indescribably powerful device built by the
Time Lords of Gallifrey. In the classic Doctor
Who story “Remembrance of the Daleks” the
Hand of Omega one-ups the Death Star by
obliterating an entire solar system (it was
full of Daleks so it’s ok). Making a star go
supernova is rather difficult to do unless it
was going to anyway, so this machine is
clearly something very dangerous indeed.
Interestingly it wasn’t even meant as a
weapon, it was a Remote Stellar Manipulator,
which, according to the Doctor is “a device
used to customise stars.” Be very wary of a
civilisation that considers supernovae an
industrial accident.
Orbital Bombardment: A favoured tactic of
many species, the massed orbital
bombardment takes advantage of the
enormous power of starship weapons to rain
death upon a plant’s surface from space.
Most times (like those damnable Cylons) this
is just aimed at blasting the cities and killing
the population, but in more extreme cases it
is designed to melt the entire surface of the
planet leaving nothing but an ocean of slowly
cooling magma. Sometimes this method uses
energy weapons, sometimes large rocks
from the asteroid belt. In lower-tech sci fi
universe it’s a massive bombardment of
ordinary boring nukes (damn those Cylons).
Massive Object Collision: Some really
powerful civilisations have even taking to
using whole planets as weapons against
other planets. The Lensmen universe has the
common tactic of teleporting a planet into
another planet’s path, resulting in a
catastrophic collision. Think asteroid impact
multiplied by about a hundred billion. It is
neither pretty nor pleasant but damn it’s
spectacular.
So, four planet killing methods. A planet
killer, a destroyer, a starkiller and a “what
the hell?” method for removing planets we
aren’t too fond of. Needless to say, please
don’t try these at home.
B Y P H I L W A L L A C E
Natural causes? Probably not in sci-fi!
Even I think this is going too far…
Page 6 C O S M O L O G I C A L N E W S
Metamorphic rocks are the hardest rocks to
see. This is due to their birth. Metamorphic
rocks are formed from sedimentary rocks
which have been buried deep in the lithosphere
and subjected to increasing internal heat and
pressure. This pressurization reshapes the
matrix and minerals of the original rock to form
a metamorphosed variation. Within the process
of metamorphism a new rock is formed out of
the original rock. It is commonplace to see
sedimentary rocks subjected to this process
whilst igneous rock metamorphism is rarer.
Metamorphism starts with the burial of the
subject rock. This can take place at plate
boundaries. It is usually seen at subduction
zones where the crustal plate is subducted
beneath another crustal plate. This can happen
between both oceanic and continental plates,
the most common being an oceanic plate sub-
ducting beneath a continental plate. Burial of
bedrock can also occur with mountain building
where the load of the mountain slowly pushes
the root of the mountain further into the litho-
sphere. However, the most common form is
found at plate subduction boundaries. As the
subject rock makes its way deeper into the
lithosphere it encounters higher pressures and
temperatures that are not typically found on
the surface. With the application of both heat
and pressure these rocks transform from their
original state into a new rock type. The rock
still contains the same minerals that made up
the original rock; however its form has been
changed. This new metamorphic rock once
formed is only seen when it is uplifted. All meta-
morphic rocks can only be seen on the surface
as we have not yet developed the technology to
access deep buried rocks in the lithosphere
(unless mining is involved). Metamorphic rocks
can usually be seen in areas of high tectonic
activity where folding and faulting of the crust
is common. The folding of rocks into an anti-
cline/syncline formation for example, will ena-
Mica Schists of the Scottish Highlands.
Anticline at Pembrokeshire.
Rock Types - Metamorphic
N O V E M B E R 2 0 1 2 I S S U E Page 7
ble rocks buried beneath the bedrock to be
seen at the surface as erosion occurs.
If metamorphic rocks are to be found other
terrestrial planets the planets must have had
previous tectonic activity; specifically plate
tectonics and folding and faulting. Also, the
surface requires some processes of erosion to
allow uplifted rocks to be seen on the surface.
Is there any evidence of these events on Mer-
cury, Venus and Mars and have they been capa-
ble of producing metamorphic rocks in the
past?
Mercury has the erosional power from solar
flares and CME’s to uncover uplifted hidden
metamorphic rocks on the surface. However,
plate tectonics has never been seen on Mercu-
ry and there is little evidence to suggest that
metamorphism has ever occurred on this small
planet. Early after its formation, Mercury start-
ed cooling. It is thought that Mercury has com-
pletely solidified since its formation and this
therefore makes plate tectonics impossible
(you need a semi-fluid mantle for tectonics to
occur). It seems that Mercury is not a planet
which could produce metamorphic rocks as it
is incapable of producing the subject sedimen-
tary rocks to start the process. Even if igneous
rock could be the subject rock, Mercury cannot
bury these rocks as it has no subduction zones
or mountain ranges. Sadly, Mercury does not
have the requirements in the past or present
to produce these beautiful rock types. Will
Venus be the first terrestrial planet other than
our own to form metamorphic rocks?
Unfortunately, the second innermost planet
Venus has a similar story to that of Mercury.
Her stable sulphuric atmosphere erodes bed-
rocks on the surface allowing previously un-
seen rocks and minerals to emerge. Whilst
talking about sedimentary rocks last week, I
said that sedimentary rocks were eroded be-
fore they could even form on the planetary
surface. Whilst this is true it also means that
sedimentary rocks cannot be the subject rock
for metamorphism on this planet. It is believed
that igneous rock is produced presently on
Venus. This suggests some kind of tectonic
activity hidden away beneath the surface. Un-
fortunately the form of this tectonic activity
does not present us with subduction zones
where rock can be buried. So, there is little
internal evidence to suggest that Venus could
presently form metamorphic rocks. Even if
Venus could produce these types of rocks, its
sulphuric acid clouds produce sulphuric rain
which covers all the rocks on the surface. The
sulphuric acid leaves the rocks with a dusting
of orange sulphur. This makes identifying rock
types on the surface extremely hard and we
have yet to properly sample the surface to see
if it produces metamorphic rock types. Maybe
Mars will be different.
Mars is a bit different from Mercury and Venus.
Hurray! Being the last terrestrial planet in our
solar system, it is a lot like Earth in its for-
mation of rock types. It was once believed that
for some time Mars possessed the ability to
move tectonic plates. With the ability to move
tectonic plates, subduction zones may have
occurred on Mars recycling the sedimentary
rocks it had produced in its early history. This
is promising stuff! However, even if the envi-
ronment was right to metamorphose any bur-
ied rock it still needs to be uplifted. If plate
tectonics were in action then folding and fault-
ing of plates could occur. This would mean that
if there is any evidence of metamorphism on
Mars we would be able to see it. With the new
missions on Mars getting underway, it will still
be another decade until we find out for sure if
Mars had produced metamorphic rocks in its
past. Whilst metamorphic rocks could have
been produced in the past they cannot be pro-
duced in the present. Mars does not possess
plate tectonics in the present as and it is be-
lieved that all of Mars has solidified now. So,
Mars is between Mercury and Venus’ inability to
produce metamorphic rocks and Earth’s ability
to continually produce different variations of
the stuff.
As with sedimentary rocks it seems that we
have most in common with Mars. However, it
will be interesting to see if that changes. There
is only one rock type left to be unearthed and
that is igneous. Stay tuned …
B Y E M M A Q U I N L A N
Page 8 C O S M O L O G I C A L N E W S
The Night Sky in November
Moon In November
First quarter: 20th November
Full: 28th November
Last Quarter: 7th November
New: 13th November
Mercury: Is at inferior conjunction with the
sun on the 17th and is not readily visible this
month
Venus: Is a brilliant morning object located amongst the stars Virgo and shining at
magnitude -3.9
Mars: is in the constellation of Ophiuchus and
is very close to the sun so little observation of
this enigmatic planet can be made this month.
Jupiter: Is in Taurus and is wonderfully bright, shining at magnitude -2.5 and is at
Opposition next month. It is almost visible all night, rising a short time after sunset. The
moon is only 1 degree south of the planet on
the 2nd of the month.
Saturn: Is a morning object in Virgo and not too far from Venus and on the 27th of the
month they pass within half a degree of each other. Saturn currently shines at magnitude
1.1 and is considerably fainter than its brilliant
neighbour.
Uranus: is still located in Pisces and is an evening object shining at magnitude 5.7 after
its opposition earlier this year. It should be visible as a distinctly green white ball with
moderate magnification.
Neptune: Is an evening object in Aquarius
with a magnitude of 7.9. A high magnification
should reveal a small blueish ball of light.
November is generally a very rainy month with only the relatively sparse Autumn constellations to observe. Neverthless, the Leonid me-teor shower, which peaks on the 17th, may give a reasonable showing – weather permitting. The summer constellations are fading fast
and the cold nights of winter are quickly approaching.
There is a Penumbral Lunar eclipse on the 28th November – the Moon will rise in eclipse from the UK but only a slight dimming of
the lunar surface may be visible.
Planets in November
This is one of the principal constellations of the Autumn sky, and can be perceived as a line of
three, second magnitude stars running eastwards from the upper left hand corner of
the winged horse Pegasus. Andromeda was the heroine of the Perseus legend, the fair maiden
that was chained to a rock to await her fate at the hands (or is it fins?) of Cetus, the sea
monster. Perseus changed Cetus into a huge rock by exposing it to the lethal sight of the
head of the gorgon Medusa, and thus rescued the lady who then became his bride, to the
delight of king Cepheus, and no doubt the
startled relief of his boastful wife Cassiopeia, who started Andromeda's troubles in the first
place.
As a constellation, Andromeda contains some
of the greatest deep sky treasures in the entire heavens, one of which is M 31, the "great
nebulae", now known as the Andromeda galaxy. Although this galaxy lies 2.9 million light years
away, this is relatively close on an astronomical scale, and the intense light of
untold billions of Suns enables the galaxy to be perceived by the naked eye as a fourth
magnitude smudge of light at the top of a line
Constellation of the month: Andromeda
The Andromeda Galaxy M 31
Page 9 N O V E M B E R 2 0 1 2 I S S U E
M57 The Ring Nebula B Y M A R T I N G R I F F I T H S
The sky in November:
The sky as it would appear at 22:00 on the 1st
of stars northward of Delta Andromedae.
M31 was not discovered by Messier, it has been
known since very early times, and many legends have grown up around this astounding object.
The first person to actually view M 31 through a telescope was Simon Marius in 1624, who
described the spectacle of its soft, glowing light as if he were looking at "a candle shining
through horn". In a pair of binoculars, the view is stunning, the bright milky nucleus does not
show the same condensation as a globular cluster would, but is rather cloudy, and a little
less opaque. The spiral arms of the galaxy can
be seen as a sliver of faint luminescence radiating out in symmetrical projection on both
sides of the nucleus. Seen through a rich field telescope, the galaxy is transformed into a
glowing elongated mass of soft white light that can be traced for almost one degree against the
darkness of the sky.
The brightness of M 31 recommended itself to
the astronomer Edwin Hubble, who was accumulating evidence that the spiral nebulae
were in fact different systems outside of the
Milky Way, island universes in their own right. During the late 1920's, Hubble began to resolve
this galaxy into stars with the aid of the newly commissioned 100 inch Hooker telescope on
Mount Wilson. The photographs obtained showed several Cepheid variables that were closely
examined over a period of months. The Cepheid period luminosity relationship was well
established at this time, so Hubble was able to calculate the distance to this nebula. Although
his conclusion of 750,000 light years is now in error, it was sufficient to prove that the "spiral
nebulae" were indeed galactic systems at tremendous distances from us. Hubble's
findings opened a whole new universe to mankind, one that has amazed, perplexed and
intrigued all manner of persons since.
M 31 is accompanied by two elliptical galaxies
that lie very close by. The brightest of these is the companion which Messier catalogued as M
32, an E4 type galaxy shining at magnitude eight, having a slightly mottled aspect as seen in a
telescope. It can be seen with binoculars as a hazy patch to the south of M 31, slightly fainter
than the nucleus of its parent galaxy, but the
brightest of the four known satellites of M31. (The other two lie over the border in
Cassiopeia). The second companion can be found to the north of the mass of the
Andromeda nebulae and rejoice in the name of NGC 205. It is a minor mystery how Messier
came to miss this companion, as through a telescope it is in the same low power field as
the others of this group. Messier certainly recorded fainter objects in his catalogue, but
perhaps he was so enthralled with the most
obvious object in this area, that he looked no
further after noting them.
Another explanation focuses on Messier’s magnification, which he universally used as x137,
rendering the field small enough to miss NGC 205 altogether. NGC 205 is an E5 type galaxy of
tenth magnitude that may be seen with good
binoculars, and is a hazy undefined object
through a small telescope.
Other objects of note within Andromeda include
a attractive loose star cluster to the south of the main body of stars at coordinates RA 01h
57m 48s Dec 37°41m. This is the galactic cluster NGC 752, a collection of 125 stars in an area of
sky larger than the full moon. NGC 752 can be readily seen in a pair of good binoculars, whilst
a telescope with a low power ocular resolves the field beautifully. The cluster lies about 1300
light years away and shows an abundance of relatively metal poor stars, thus making this
group a rather ancient cluster.
Going in the opposite direction, to the northwest
of M 31 lies one of the nicest planetary nebulae
in the Autumn sky, one that is best seen with a telescope, but can be viewed with a pair of
binoculars, although through such instruments it is an unremarkable object. This is NGC 7662, a
round, greenish - blue planetary close to the star 13 Andromedae at RA 21h 01m 30s Dec16°
11m. It is an arresting sight in a telescope as it shines brightly at magnitude eight, and shows a
perceptible disc that is the trademark of objects of this type. NGC 7662 is fairly remote, about
5600 light years, giving the nebulae a diameter
of almost one light year. To my eyes its colour is a pale blue, almost tinged with green; examine it
and draw your own conclusion.
Page 10 C O S M O L O G I C A L N E W S
Many Faceted Planet
Formation
Prior to the discovery of extra-solar planets and before we were forced to face up to our
anthropomorphic naivety it was thought that all planets were made, or could be made, using the
same basic approach. The formation of the solar system from the collapse of the solar
nebula some four and a half billion years ago
was that approach.
It was debated as to whether the large gaseous
outer planets were formed quickly through the disk instability process where knots of the outer
portion of the nebula collapsed quickly (in a few
thousand years) and gravitationally attracted more gas so growing in size ( the top down
model) or whether, like the inner rocky planets, they had grown by an accretion process (the
bottom up model) taking perhaps 50 million
years or more.
The first intimation that this cosy little picture
was much too limited a scenario came in 1992, when Wolszcan and Frail announced the
discovery of two planets around the millisecond
pulsar (a rapidly spinning neutron star ) PSR
1257+12.
Initially there was a lot of scepticism because
this did not fit in with the preconceived
notion of planetary formation.
However the claim was quickly checked and
confirmed and then there was no doubt.
The debate then was about how there could
possibly be planets in this most unlikely
of places. The neutron star was formed when the progenitor star went supernova in a
colossal explosion. It would now appear that
the material from which these two planets formed was the debris left behind from a
companion star that had been destroyed during
the supernova explosion.
PSR B1620-26 b is a planet that orbits a binary star One of the stars is a neutron star, a
pulsar, spinning at 100 revolutions per second. The other is a white dwarf with a mass of about
one third that of the Sun. These stars orbit each other at a distance of 1 AU about once every six
months. The planet orbits both stars centre of mass at a distance of about 23 AU. This planet
has a mass about two and a half times that of Jupiter. This pulsar planet was probably
orbiting the star that is now the white dwarf when it first formed. This system is to be found
inside Messier 4, a globular cluster. Globular
clusters are spherical volumes of space that
contain large numbers of closely packed stars.
The gravitational interactions between these stars means that there is a considerably
greater probability that stars will have close encounters that can result in changes to their
relative velocity and direction of movement. The thinking now is that the star which formed the
white dwarf ( and which had the planet ) was captured by the neutron star after it had gone
supernova. The planet ended up orbiting both
stars rather than just the one because of the changes to the system that occurred at the
time of the encounter.
Another feature of the changes in thinking about planet formation within the last twenty years or
so is the way in which the first detection of a Hot Jupiter by Mayor and Queloz in 1995 caused
a crisis in confidence in astronomical circles regarding how and where large gas planets
form in relation to their star. Hot Jupiters are planets that have approximately similar mass to
Jupiter but are found in close proximity to their
star. So close in fact that it would not be
possible for them to have formed in situ.
This discovery precipitated a plethora of scientific papers on possible mechanisms for
planet migration within planetary systems. Migration is now an accepted part of the
thinking regarding the formation of planetary systems. Many Hot Jupiters have been
discovered since.
The idea that planets can form in multi-star systems has been around a long time and there
has been many computer simulations carried out that confirmed this. Planets can be in stable
orbit around one star in a binary system as long as their relative orbits and masses are such
that drastic interactions between the members of the system are a thing of the past. There are
many examples of this in the nearly 700
exoplanets that have been confirmed to date. Most are widely spaced binaries in which
separate planet formation around each presents no problems. However planet
formation around stars in tighter configurations
is also possible.
Gliese 86 is an example of such a system. The
largest star is a K type with about 80% the mass of the Sun. The small star is a cool White
Dwarf thought to have a mass of about half that
of the Sun, although this has been problematic to determine. The average distance between the
two is some 18 Astronomical Units. It has been determined that the K type star has a planet
orbiting it with a semi-major axis of about 0.1 AU. This planet seems to be a hot Jupiter with a
mass of 2 to 3 times that of our Jupiter.
A planet orbiting two main sequence stars has now been confirmed. Kepler 16 is a tight binary
with one star having about 70% the mass of the Sun. The other star has a mass of about 20%
that of the Sun. The planet discovered is similar
in size to Saturn and lies in an orbit that is approximately the same distance from the
centre of mass of the system as Venus is from
the Sun, see the illustration below.
Page 11 N O V E M B E R 2 0 1 2 I S S U E
A recent study on possible scenarios for the formation of our Solar System has concluded
that the present arrangement of our outer
planets would have been unlikely
if the system had started with the four large planets that we have. A much likelier starting
arrangement would have been five large planets with one of them being ejected from
the Solar System after a comparatively short period. The gravitational interaction between
Jupiter and Saturn as they both migrated inward would have been the main reason. This
idea leads us to consider what would have
happened to the fifth planet after its ejection.
It must still be out there somewhere in
interstellar space. So if this had happened in our system then there is no reason to think
that it would not have happened around other stars. Therefore there must be a population of
lone planets, between stars, orbiting the centre of the Galaxy, that are not attached to
any star. A study looking toward the centre of our Galaxy for comparatively small objects
that block radiation, called microlensing, has
detected 10 events that would seem to suggest that there are many millions of free floating
planets in the Galaxy. They are going to be
difficult to pin down.
Very recently a pulsar named PSR J1719-1438 has been investigated and it has surprised the
scientists involved. The radiation emitted from the Neutron Star is modulated by the presence
of a comparatively small body that can have a diameter no more than half that of Jupiter. Its
distance from the surface of the Neutron Star is about 600,000 kilometres. At this distance
the tidal forces involved should really tear it apart. Yet it has not done so. The material from
which it is made is dense and is probably the tiny central remnant of a star that has been
systematically robbed of its material by its
companion. The planet sized remnant affects the Pulsars radiation in a way that suggests
that it has a crystal-like structure. The core material of the dispossessed star is probably
Carbon and/or Oxygen and so this object has
been called the Diamond Planet.
This was an entirely unexpected way to make a
planet. It would now appear that there are many ways to make a planet and there are
many routes that a planet can follow through
its short or long lifetime.
Planets are obviously ubiquitous and full of
surprises. The only thing about them that is predictable is that they will surprise us again.
It seems to be the case that any mechanism we can dream up will have been tried out by
nature already and some have been tried out
that we haven't been capable of dreaming up.
The relative eccentricity of the orbits of such
stars is an important parameter in determining how many planets can survive in
that system and where they will end up relative to each other. The more eccentric the orbit the
less room there is for planets in the limited
space available before instability sets in.
Circumbinary orbit
T E R E N C E M U R P H Y
Planetary system formation
BSc (Hons) Observational Astronomy
The question of whether there exists a supernatural creator, a God, is one of the most important that we have to answer. I think that it
is a scientific question. My answer is no. -Richard Dawkins
