Sun, Moon & Planets
www.Derbyskywatcher.co.uk

| Location : Derby | Lat : 52.91N | Lon : 1.47W |
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Our planet is just one in what is
called the solar system. We share this corner of space with 7 other
planets (and Pluto*), their 60 moons, an asteroid belt, some comets and
the Kuiper belt. In this section I am going to talk about our local
solar neighbourhood and how much of it you can see from our little planet.
Most peoples’ first encounter with celestial bodies is with our own moon. Our moon was originally formed some 4.3 billion years ago when a large chunk of rock (about the size of Mars) slammed into the Earth. Due to the Moon's own orbit and rotation period only one side of the moon ever faces the Earth. Ever since I was a child I've looked towards the moon with awe, something that you will probably be able to tell from all my pictures.
Note: The above moon calendar uses active-x plug-in, some
browsers may block this by default. You may need to manually
configure your browser to allow blocked content.
When we think of the stars in the sky we tend to overlook our own sun. Alongside all the others stars in the galaxy it is of average size, temperature and brightness. Temperatures at its core are estimated at a scorching 15 million oC. This is relatively cool compared to other stars. The Sun appears to have been active for 4.6 billion years and has enough fuel to go on for another five billion years or so. At the end of its life it will begin to swell, ultimately growing so large that it will swallow the Earth. After a billion years as a red giant, it will suddenly collapse into a white dwarf. It may then take a trillion years to cool off completely. Every second, the sun produces energy equivalent to 35,000,000 times the annual electricity consumption of North America.
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Mercury is the closest plant to
the sun, but is fairly difficult to see due to its low position in
the sky. At less than half the diameter of the Earth it is a small
planet that resembles our own Moon with its surface being dotted
with thousands of craters. During the day its surface is scorched by
soaring temperature and sunlight, yet over night it plummets below
freezing.
Venus is sometimes referred to as
our sister planet due to its closeness in size (only 400 miles in
diameter less) and makeup. On its orbit it comes within 25 million
miles, closer than any other planet, and therefore after the sun and
moon is the brightest object in the night sky. It may well be very
similar to Earth, but it’s not somewhere we would like to live -
clouds of sulphuric acid (H²SO4), an atmosphere of almost entirely
Carbon Dioxide (CO2) and gravity about 90 times greater than on
Earth make this a truly inhospitable place.
Our home planet, the largest of
the four inner planets, is 3 planets from the sun in what is called
the 'safe zone'. Named this because any closer in and it would be
too hot to survive and any further out and it would be too cold.
Earth, as far as we know, is the only planet in our Solar System to
support life and so far this is also true for the rest of the
universe - can that really be possible?
Nicknamed the Red Planet due to
its surface of red deserts. Venus may share the physical
characteristics of Earth but it's Mars that is the most similar. It
has a 24 hour day, what could be described as seasons and polar ice
caps. However before we all rush off it might be noted that the
temperature on Mars rarely rises above freezing, with a thin
atmosphere with almost no oxygen.
Jupiter is truly a giant, it is
the largest of all the planets so much so you could fit all the
other planets of the Solar System inside it. Jupiter has the
shortest days of the 8 planets, rotating once on its axis in under
10 hours. This size and speed has played a major part in our very
survival. Its size and immense gravitational pull has been our
saviour from many space born attacks from comets.
Other than Earth, Saturn is probably
the most well known member of the Solar System, and it owes this to
its rings. From Earth through a modest pair of binoculars or a
telescope they may look solid but they are in fact tiny rocks and
dust trapped in this giant’s orbit. Although Saturn is huge, it is
surprisingly light, if there was a body of water large enough
to contain it then it would float.
Uranus is the 3rd largest of the
planets (behind Jupiter
and Saturn) yet it was
only discovered in 1781. Two things of interest (or unusual) about
this gas giant is that a) apart from a few small cloud fronts its
surface is almost entirely featureless and b) it rotates on its
side!
Neptune is the outermost of the
gas giants. Like Uranus it has an atmosphere rich in hydrogen,
helium and methane, and it too has faint rings. Neptune was
discovered in 1846 after disturbances caused by the gravitational
pull of Uranus were noted. Little else was known until Voyager 2 space
probe made a fly by in 1989.
Although only two thirds the size
of our Moon (and smaller then Io, Europa, Ganymede, Callisto, Titan
and Triton) Pluto was regarded as a planet in the solar system
for many years. However on August 24th 2006 it was reclassified as a
dwarf planet. The surface temperature on Pluto varies between about
-235 and -210 oC. It has one orbiting moon, Charon,
although Hubble has recently discovered two more objects in orbit,
named Nix and Hydra. |
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| Eris | |||||||||||||||
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Eris looks like it is about 2,700 km
(1,700 miles) across. It is too far away and very hard to see, even
with the world's biggest telescopes to be sure, but it's probably
larger than Pluto. |
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| Ceres | |||||||||||||||
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| The Kuiper Belt | |||||||||||||||
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KBOs are gigantic balls of
ice and rock. Some are relatively small, some are tens of km across, and some
are as big as the 'planet'
Pluto, and may be larger! They orbit the
Sun
on the edge of the Solar System, near Pluto. They orbit between 30
to 50 AU (1 AU = Earth to Sun distance) from the Sun. Some
astronomers think the Kuiper Belt goes out to 100 AU. KBOs take 200
years or longer to orbit the Sun! |
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