ASTRONOMY 101: EARTH'S MAGNETOSPHERE

The magnetosphere is a protective field that extends thousands of miles into space. Its magnetism affects everything from global communication to weather patterns. Created by the Earth’s spinning molten core, its existence means that the charged particles of the solar wind are unable to cross the magnetic field lines and are deflected around the Earth towards the poles. This causes beautiful auroras, sometimes appearing far south of their indigenous polar regions, like the recent displays in mid latitude zones.

This life-protecting magnetic field, has decreased by fifteen per cent over the last two centuries. Some scientists think this could be an indication that the Earth’s poles are about to exhibit a long overdue flip. The Earth would be exposed to ozone layer damaging solar winds while power supplies are wiped out, the climate is changed and cancer rates rocket.

ASTRONOMY 101: JUPITER

What’s that really, really bright star slightly south west of overhead (or zenith) at the moment that you can see from all over the Northern Hemisphere at dusk?  Well actually, it’s not a star it’s the solar system gargantuan gas giant planet Jupiter, which is making its presence felt in no uncertain terms at the moment.  Jupiter is nearly large enough to be regarded as a failed star.  It has a similar composition to the Sun that is mainly hydrogen and helium and emits large quantities of radiation.

It’s easy to tell it’s not a star as planets don’t twinkle.  Planets are very close to the Earth in astronomical terms and hence unlike stars aren’t point sources of light, but show proper discs.  If you look at Jupiter with binoculars you'll probably see on either side of it some of its entourage of moons. With a telescope you should be able to make out a couple of dark belts crossing its disc.

These are the planet’s spectacular cloud bands composed mainly of methane and ammonia, impurities in the planet’s immense atmosphere.  Look closely and you’ll see a gigantic red spot, a huge storm that has raged for over four hundred years!

ASTRONOMY 101: BINOCULARS

Despite having a couple of sizable telescopes my favourite piece of astronomical equipment is still a humble pair of binoculars that I bought at a car boot sale for under 5GBP!  They are portable, light and easy to use on cold, damp but clear nights!

My 10 x 50 Super Zenith binoculars bought for 5GBP second hand.
 With a Field of View (FOV) of 5.5 degrees they make for fantastic
views of open star clusters and some of the brighter deep sky
objects such as M31 The Andromeda Galaxy and M42, the Great
Nebula in Orion.

And they are all you need to get the ‘wow’ factor from a selection of objects that are annoyingly just beneath naked eye visibility in this month’s night sky. From a reasonably dark location in the Northern Hemisphere binoculars will bring the Andromeda Galaxy into view, along with the star forming nebula in the hunter’s sword in the constellation of Orion after dusk.

The moons of Jupiter will magically appear, as will a multitude of star clusters.  Paradoxically, some objects actually appear more spectacular through binoculars than through a telescope, due to their large field of view. The Seven Sisters or Pleiades is an example of this, and binoculars show that there are many more stars in the cluster than just seven!  The Moon is stunning at any time with its craters such as the magnificent Tycho and Copernicus.  Binoculars will give you great views of the lunar Mare or Seas such as the Sea of Tranquility where men first landed in July 1969!

ASTRONOMY 101: THE MOON

Our Moon is far more important to all life on Earth than most people realise.  Simply illuminating the night sky or being responsible for ocean tides is of relatively little significance when one realises its true effect on the Earth and us.  It has been intrinsic to the very evolution of life itself, and by definition the appearance of homo sapiens!  And it's not hard to see why it is so important. 

The Moon with labelled 'seas' and craters.

To start with it is the only Moon of a major planet in the solar system that is so large relative to its parent planet, indeed many astronomers consider the Earth/Moon system to be a double or binary planetary system.  At 385,000 kilometres distant it is the closest celestial body to the Earth.

The Moon was created from the Earth itself, confirmed by the geological experiments undertaken during the NASA Apollo program.  Unlike the Earth, there is very little iron on its surface and it consists of terrestrial mantle material.

ASTRONOMY 101: THE SUN

The Sun is an ordinary star and is the brightest object in our sky.  As such you should certainly never look at the Sun directly and certainly never through binoculars or a telescope.

It’s one of more than one hundred billion stars that populate our Milky Way galaxy.  It’s a gigantic ball of hydrogen 870,000 miles wide.  The Sun has a diameter 109 times that of the Earth and is one third of a million times its mass.

The Sun collapsed from a cloud of hydrogen gas approximately 4.5 billion years ago.  The pressure and temperature of the hydrogen in its centre became so great that nuclear fusion chain reactions started where 600,000,000 tons of hydrogen are converted into helium each second.  In the process, under Einstein’s famous equation E equals M C squared, a small amount of mass is lost as energy including light.

This energy is what we and all living things depend on for our existence.  The visible light we see from the Sun takes eight minutes to travel the 93 million miles before it reaches our eyes and is only a small part of the energy released from our star.  Its nuclear reactions also produce vast quantities of ultra violet light along with deadly x-rays and gamma ray radiation.  Indeed if it wasn’t for the Earth’s protective magnetic field this radiation would strip off our life-giving atmosphere and all life on Earth would be burnt to a crisp.

Temperatures at the core of our star Sun reach a staggering 10 million degrees Celsius, but it’s surface is less hot at about 5,000 degrees Celsius.

The Sun consists of approximately 75% hydrogen and 25% helium and is halfway through its life.  In 4.5 billion years it will run out of its hydrogen fuel and will start to fuse helium into even heavier elements.  In the process it will become a bloated Red Giant star that will engulf the orbit of the inner planets.  Finally it will puff off its outer layers as a planetary nebula before contracting to the size of the Earth.  It will have become a white dwarf star made of pure carbon diamond… a cosmic ember.  I don’t think however we’ll be around to see it!

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