Astronomy
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"There is a theory that if anyone ever discovers exactly what the Universe is for and why it is here, it will immediately disappear and be replaced by something even more bizarrely inexplicable.
There is another theory which states that this has already happened...
There is yet a third theory which states that both the first two theories were concocted by a wily editor of the Hitchhiker's Guide to the Galaxy in order to increase the universal level of uncertainty and paranoia, and so boost sales of the guide. (Douglas Adams)"
There are many wonderful areas of study in
Science and Technology. However, to me, the most interesting is
that of Astronomy. This is the Science that encompasses many
others - Physics, Chemistry and Biology. When we look around us
and see the everyday problems and those more serious which beset
us, it can sometimes be a sobering thought that the Universe is
an enormous place and natural disasters can occur of an
unimaginable scale - a whole solar system can be wiped out in a
fraction of a second. Planets can be destroyed by collisions with
other objects - and we worry what colour the curtains should be!
Even in Earth's history, it appears there have been cataclysm's
on a planetary scale - these may be some cause for concern.
As these pages are developed, I will try to share some of my thoughts and understanding of Astronomy with those of you who care to visit. I will also try to include some pages on other areas of scientific interest.
Below is a brief description of our Solar
System which attempts to include some interesting and lesser know
facts. The planets are described from closest in to the Sun to
furthest out. For a full description, please try to obtain a book
such as The New Atlas of The Universe by Patrick Moore, or
even something like Encarta (if you have a multimedia PC),
which gives plenty of info to get you going. A good site to look
at is "Views of the Solar System". You could also try Exploring
Our Solar System - and Beyond. Other
sites are also listed on the "2 Oz of Cyberspace
Please!"
The Solar system is believed to have formed out of a cloud of material which circled the Sun. The process by which it formed is still not well understood.
The Sun is termed a "Main Sequence"
star. It is a huge sphere of Gas Plasma and is currently still
undergoing internal nuclear fusion of Hydrogen to Helium. Nearly
all life on Earth is supported by the energy produced by the Sun.
In about 5 million years time, all of the Suns hydrogen will have
been fused into Helium and it will begin the next stage of its
life by becoming a Red Giant. A single photon of energy takes
several million years to travel from the interior of the Sun to
the exterior and it completes its journey to the Earth in about 8
minutes.
Is a rocky, lifeless world about 35 million miles from the Sun. Its surface temperature varies from -180C to 430 C, and resembles that of the Moon. It was careful, accurate observations of Mercury which were used as evidence to back up Einstein's Theory of General Relativity in the early 1900's.
It is only occasionally visible from the Earth,
because, in the sky, it spends much of its time close to the Sun.
Some people have claimed to see another planet in transit across
the Sun's disk - the Planet was called Vulcan. However, there is
no evidence to support it's existence, so it may have been some
other unknown object.
Is about 67 million miles from the Sun and is
an unusual world - shrouded in a thick atmosphere, with clouds of
sulphuric acid. It is thought to be the victim of a runaway
Greenhouse Effect which keeps its surface temperature at about
450C. It is nearly the same size as the Earth, but there the
similarity ends. Its opaque atmosphere gives it a very high
albedo (it reflects a lot of light) and to us from Earth, it
appears as the brightest object in the sky apart from the Sun and
moon of course! In fact, so bright is it that many people, when
they see it can not believe that it isn't a UFO or something very
unusual.
Its inhospitable surface has been photographed
by a Russian Probe and because of the thick atmosphere, it has
taken the Magellan Probe to map the topography of the surface
using radar. Venus turns the opposite way to all the other
planets - this is termed "retrograde motion". Some
scientists have proposed "Terraforming" Venus by
introducing Nostoc algae into the upper atmosphere, to try to
reverse the Greenhouse effect.
It's about 4 billion years old, and some
scientists argue that if it had been a little bit closer to or a
little bit further away from the sun, life would never have
evolved. It is currently the only planet we know of that supports
life. Its magnetic field appears to swap over approximately every
600,000 years.
The Earth is undergoing "precession"
its access of rotation (see picture above), describing a circle
once every 24,000 years. Hence, in 1000 years time, what we now
think of as the Pole Star will not appear to us at the same point
in the sky. Once one accepts the Earth's precession, it becomes
clear that Astrology has no firm basis to work on - the
apparent position of constellations in the sky varies in a 24,000
year cycle. The current Astrological signs were "thought
up" about 2000 years ago - one twelfth of the 24,000 year
period - therefore all the star signs are out of step by one.
There is still some debate as to how the moon
was formed, though most people believe it was once part of the
Earth. The ratio of the size of the Moon to the Earth is large
compared to all the other planets in the solar system. The
craters on the Moon are thought to be largely impact craters and
seem to be a reminder of a once turbulent period in the history
of the Solar System. Though most people seem to accept the moon
is a dead world in almost every sense, with no atmosphere, let
alone life, others claim to have observed emissions of gas and
dust (termed Transient Lunar Phenomena), which goes against the
idea that there is no volcanic activity on the Moon and little
seismic activity.
The Moon is 400 times nearer to us than the
Sun, but is also 400 times smaller - a bizarre Cosmic Coincidence
which makes a total solar eclipse possible as shown here and also here. Eclipses follow an
18 year cycle called The Saros.
Another effect seen from the Earth is a Lunar Eclipse, where the Moon passes through the Earth's shadow and, starts to come out
again. All these pictures came from The
Astronomer Magazine. Browse this site
for some of the latest news and pictures.
The Moon takes 29.5 days to rotate on its axis
and it goes round the Earth the same period, therefore always
keeps the same face turned to us (this has come about due to a
kind Gravitational Drag). The Moon's motion around the Earth
causes the Tidal cycle in the oceans.
The Red Planet - till early this century many felt it must be inhabited. It has a thin atmosphere, mainly composed of CO2. Surface features seem to indicate the presence of water in the past, but most of it seems to have evaporated away into space.
Recently an ancient Martian rock has been analysed by NASA and other scientists (ironically, this was not one collected by the Viking Missions in the 1970's) which appears to contain some genetic material. This seems to indicate that there was some life on Mars between 3.6 and 4 billion years ago (probably only bacteria).
From here, Mars appears bright red in the sky and some surface features are visible with a modest telescope. It has 2 mis-shapen moons, Phobos and Daemos, which themselves have some interesting properties.
Mars has one "outstanding" surface
feature - an enormous Shield Volcano, Olympus Mons, which is 27km
high (although this not visible with small telescopes).
Between Jupiter and Mars lies a ring of
Asteroids - a huge number of objects ranging in size from grains
of dust to Ceres, Vesta and Pallas which are several hundred
kilometres in diameter. Some people believe the Asteroid Belt is
the remains of a planet which has broken up, However, it seems
more likely that it is material from a planet which never formed.
The largest planet in the solar system, is a
fascinating world about which a great deal has been discovered
this century by the Pioneer and Voyager probes. If it had been
much larger, it would've been a "sub-stellar object".
As it is, it gives out more heat than it receives from the Sun.
It is known as "a gas giant" and has
numerous moons and a solitary, faint ring. In the sky, it appears
a creamy white colour, only outshone by Venus. In a small
telescope, the main cloudbelts are visible, as are 4 of the moons
- Ganymede, Io, Callisto and Europa (the so-called
"Gallilean Moons" as Galileo discovered them with early
telescopes he made). It is possible, in a single evening with a
small telescope, to observe moons passing across the yellow disk
of Jupiter.
Jupiter emits huge amounts of radiation and
evidence of huge thunderstorms in its atmosphere can be heard
even here on Earth - some 400 million miles away - by listening
to certain radio frequencies.
The Great Red Spot is a mystery in that it is a
persistent feature, it seems to be a "self-sustaining"
transverse wave of atmospheric turbulence.
Another Gas Giant, whose intricately beautiful ring system is visible from the Earth even with a modest telescope. I will never forget the first time I saw this strange looking "star" through a telescope. Saturn resembles Jupiter in colour, but it is sometimes stated it is the only planet that would float in water - because its specific gravity is less than 1. Again, the Voyager Probes have revealed much about this world and some its numerous moons.
Was the first "new" planet to be discovered - all the others described above are visible with the naked eye. William Herschel discovered it accidentally in 1781. Up until 1986, the best pictures from Earth showed it as a featureless disk. Once again, the Voyager probe gave us much better pictures and discovered 10 new satellites.
The planet has a tenuous ring system, which was discovered in 1977 by observation of radio waves when the rings occulted a star. Voyager discovered a further 4 rings.
Uranus is inclined at 98 degrees to the plane of its orbit (compared to about 23 degrees for the Earth). This means that, in its 84 year orbital period, the North Pole and South Pole each experience, 21 years of total darkness, though because of characteristics of the atmosphere, it is often the case that the pole furthest from the Sun is warmer.
The reason of the 98 degree inclination is not clear, though there is a theory that many thousands of years ago, Uranus was struck by a large object which caused chaos in the Uranian planetary system - the planet was "knocked off its axis" and the resulting effect on the moon system was catastrophic - with some moons being totally destroyed and others "smashed to pieces". Some of the moons may have coalesced and re-formed in new orbits. This would explain unusual surface features where only half a crater is seen and there are strange discontinuities in valleys etc. It is also believed that this could explain why Pluto appears to be very similar in composition to some of Neptune's moons - Pluto could be an ejected moon of Neptune - the collision even affected the Neptunian system.
Sister planet of Uranus, was discovered in 1846
after its existence had been mathematically predicted. One of its
8 moons, Triton, was also discovered that year. 2 moons are
visible from Earth, 6 were discovered by Voyager. When Voyager
passed the Planet in 1989, it was travelling at such a speed that
it had to take all the pictures in 8 minutes. "Geysers"
have also been discovered on the moon Triton, which are unlike
anything else in the solar system. Neptune has a system of 5
tenuous rings.
Relatively little is still known about this
planet - observations have now shown it to be much smaller than
originally thought - about the size of the moon. It has a
satellite of its own - Charon - which is large in comparison to
Pluto itself. Recently, the Hubble
Space Telescope has revealed some surface features of
Pluto.
Click here....
