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If you have no idea what to do on a dark cloudless night, take a trip into the countryside (or take a trip outside the front door if you are already in the countryside), and check out the vast pattern of galaxies, stars, planets, meteors and satellites that surround our little planet. It's fascinating. No equipment is necessary, but if you have a pair of old binoculars, without special coatings or zoom features, that's a benefit. Even without binoculars there is plenty to see. Also, you should have plenty of warm clothing. Naked astronomy is only for real fanatics.
The next thing you will need is a serious absence of light. Industrial and residential lighting will really upset your chances of seeing anything worthwhile, so go as far away from built up areas as possible.
If you know nothing, or very little, about astronomy, but you are interested in knowing more, below you will find a quick introduction to the night sky. It will tell you what to look out for, what these things are, and some facts for you to truly appreciate what it is you're looking at.
Everywhere you look on a clear night you will see stars. Stars are massive objects where the material inside is so tightly packed together by gravity that the atoms inside combine together, releasing an enormous amount of energy in the form of nuclear fusion. The Sun is a star, and not a very big one at that - the amount of energy released is defined by Einstein's equation E = mc2.
Stars appear tiny because they are extremely far away - the nearest one to us is about 27 million million miles away. If you were up close and personal they would look a bit more like our Sun.
Our Sun is 865,000 miles in diameter, and 93 million miles from Earth. Its gravity holds nine planets in its orbit. That's a fact we all may take for granted, but it gives an idea of the sheer size and strength of this Sun. Remember that the ninth planet, Pluto, is 3666 million miles away from the Sun.
The Sun is 74% hydrogen and 25% helium. The remaining one percent is oxygen and other matter. The Sun is 25,000 light years away from the centre of the galaxy, and shares the rotation of the Milky Way. It moves at 220km a second, and takes 225 million years to do a full circuit. This should help you appreciate how big the Milky Way is - remember that our galaxy is one of the smaller ones.
Stars are classed together into constellations as a means of easily identifying the location of all objects in our night sky. A constellation is a group of stars that resemble a shape of some sort. These are used by astronomers to help identify stars. There are 88 constellations in the sky, with different ones to be seen in the north and south hemispheres.
Clusters are concentrated groups of stars, which can sometimes number in the tens of thousands. The most well-known cluster is the Pleiades, visible with the naked eye during most of the year. Close by is the Hyades in the constellation of Taurus. Look at them through binoculars and you will see a feast of stars.
The North Star
By a complete accident of nature and good timing, a bright star, Polaris (alpha Ursae Minoris), is situated at the point of the northern geographic pole. This means that the star does not move much from its position in the sky. The North Star is useful for getting your bearings and finding which way is north. Humble apologies, by the way, to all Southern Hemisphere readers, who don't have such a convenient landmark situated at the South Pole, although you can find due south using a combination of the Southern Cross and the Pointers.
The Moon is Earth's closest natural astronomical companion, and the brightest object in the sky after the sun. The Moon completes its cycle around the Earth once every 28 days. Because the Moon revolves from night into day at the same rate at which it rotates around the Earth, we can only ever see the same side of the Moon from Earth.
The dark blotches on the moon are lava plateaus known as mare. Looking at the moon through a telescope or binoculars will enable you to see craters and mountains on its surface. These are from meteorites. Since the moon has very little atmosphere, marks made on the surface - from an astronaut's footprints to one of the aforementioned meteorites - will stick around for thousands of years.
Planets are often mistaken for stars. Planets are bodies, like Earth, that rotate around the sun. The most clearly visible planets from Earth are Venus, Mars, Jupiter and Saturn. These objects are brighter than most stars, and you can see at least one of them on most nights.
If you look at Jupiter through a telescope or binoculars you will make out small dots on the same line at either side. These are the four largest moons of Jupiter: Io, Europa, Ganymede and Callisto. You can see the rings around Saturn through a telescope.
If you go out on a dark night any time of the year and wait around for a while you are bound to see a few meteorites . Meteorites are small dust-sized particles that collide into the Earth at high speed, burning up in a split-second. Larger objects also hit the earth's atmosphere, producing much brighter fireballs - this is a rare occurrence, but more common at certain times of the year, especially November and December, during the Leonid and Geminid meteor storms.
The space around the Earth is now populated my many man-made satellites. Satellites such as the International Space Station (ISS), the Hubble Space Telescope, the Chandra X-ray observatory, and numerous telecommunication, scientific and spy satellites all follow elliptical orbits around the earth.
Satellites normally look like small dots moving relatively quickly against the stellar background. A recent addition is the Iridium network of satellites that produce bright flares almost every evening and morning if you know where to look. Check out the web page Heavens-Above if you would like to see a satellite passing over.
Galaxies are conglomerations of billions of stars. Our sun is part of a galaxy known as the Milky Way. No other galaxies can be seen with the naked eye, but a pair of strong binoculars will help to reveal M31 or Andromeda, a massive galaxy like our own. It looks like a bright foggy area against the dark background, but patience is needed! It's not an easy object to spot. Other galaxies will need the services of more powerful telescopes.
The Milky Way
The Milky Way is a galaxy, a massive collection of stars, hundreds of thousands of light years in diameter. If you wait a while on a really dark night, you will see a milky band crossing the sky, which in reality is the millions of stars contained in our galaxy.
Comets pass by Earth regularly, but only on very rare occasions are they visible through the naked eye. A comet is a large icy object which originates from the distant parts of our solar system. It can take many months to pass around the Sun, and a great trailing tail of ice particles and gasses blown out by the solar wind is a common feature. Some comets are regular and predictable, but many of the most famous comets - such as Hale-Bopp in 1997 - arrive without any advance warning.