Europe and Africa Geographical Facts

Europe has about 10,180,000 square kilometres (3,930,000 sq mi) and represents the world's second smallest continent by surface area after Australia. With a population of 731 million (or 11% of the Earth's population), Europe is the third-most populous continent after Asia and Africa. Africa is the world's second-largest and second most-populous continent, after Asia. It has an area of 30.2 million square km (11.7 million square mi) and a total population of 1 billion. Africa covers 20.4% of the Earth's total land area and it accounts for about 14.72% of the total human population. Here is a list with interesting geographical facts about these continents:

• Switzerland has four official languages: German, French, Italian and Romansh.
• The Danube river passes through four European capitals: Wien, Bratislava, Budapest and Belgrade.
•  Luxembourg is the country with the highest steel production per capita in the world - approximately 4 tonnes of steel for each inhabitant. 
• The belgian city of Antwerp is one of the most important diamond trade center in the world.
• The Öresund Bridge connects Sweden and Denmark, and it is the longest road and rail bridge in Europe (7.8 km or 4.8 mi).
• With a height of 3,718 m (12,198 ft), Mount Teide located in the Canary island of Tenerife is the heighest elevation in Spain.
• Germany borders with nine land neighbours: Austria, Belgium, Czech Republic, Denmark, France, Luxembourg, Netherlands, Poland and Switzerland.
• 65% of the total land area of Sweden is covered with forests and 15% of its area lies north of the Artic Circle.
• Sicily is the largest island in the Mediterranean Sea. This island has an area of 25,711 square kilometers (9,927 square mi) and a population of 5 million.
• 10% of the population of Turkey lives in the European part of Turkey which represents only 3% of its total area.
• The Lötschberg Base Railway Tunnel in Switzerland is the world's longest land tunnel (it has a length of 34.57 km or 21.48 mi).
• 19% of the total electrical power production of Denmark is represented by the wind power.
• The Kaliningrad region is a province of Russia that is situated between Poland and Lithuania on the Baltic Sea.
• - You can find four European countries in the global top ten Gross Domestic Product rankings: Germany, France, Great Britain and Italy.
• France is the most visited country in the world and its capital Paris is the most visited city.
• Africa is the only continent to stretch from the northern temperate to southern temperate zones.
• Lybia has the longest official country name: Great Socialist People's Libyan Arab Jamahiriya.
• With 9.4 million square km (3.6 million square mi), Sahara is the world largest desert. Its area is comparable with that of Europe or the United States of America.
• The three main rivers of Africa are: Nile, Congo and Niger.
• Lake Chad, in Central Africa, has an average depth of 1,5 metres.
• The official language of Angola is Portuguese.
• The National Parks represent about 3% of the total area of South Africa.
• Burkina Faso was formerly called the Republic of Upper Volta.
• Cairo, the capital of Egypt, is the most populated city in Africa.
• The lowest point in Africa is lake Assal in Djibouti with 156 m (512 ft) below the sea level.
• With an area of 10,380 square km (4,007 square mi), Gambia is the smallest country on the African continent.
• 50% of the population of Uganda is less then 15 years old.
• South Africa has three capital cities: Cape Town is the legislative capital, Pretoria is the administrative capital and Bloemfontein is the judicial capital.
• Monrovia, the capital city of Liberia, was founded in 1822 and it was named this way after the US President James Monroe.
• Over 60% of the population of Ethiopia is made up of Christians.
• Bir Tawil is an area on the border between Egypt and the Sudan and it is the only piece of land on Earth that is not claimed by any country.

How to Take Deep-Sky Astrophotographs

Deep-sky astrophotography is said to be easier than taking photographs of the Moon or the planets because there is an excellent chance that a good image will be captured on the first attempt. However, this does require the acquisition of extra equipment and skills.

The telescope needs to be mounted equatorially for a start, either with an equatorial mount or a wedge. Added to this, an eyepiece with crosshairs will be needed for guiding the telescope. The reason for having to guide the telescope is because telescope motor drives are hardly ever perfect, which means that manual corrections have to be made in the east-to-west direction in order to smooth out any erratic motion. Also, any tiny errors in polar alignment will need to be counteracted in the north-to-south direction.

If shooting the sky in piggyback mode, with a camera mounted on top of the telescope, guiding is easy; you just watch a guide star through the telescope, keeping it on or close to the crosshairs. When piggybacking with a medium-power telephoto lens attached to the camera, precision guidance is not essential - just keep the guide star somewhere close to the crosshairs.

The secret to good guiding is to ensure that only the equatorial motor drive is running, set the slew rate to a low value and turn off any backlash compensation to make sure that there is no unexpected jerking. Guiding corrections are best delayed rather than for them to be made suddenly or irregularly.

When taking shots through the telescope, guiding can be more challenging because there is little room for error, with the guide star having to be kept right on the crosshairs. But how is the telescope guided when it is being used to take a photograph through?

One method is to employ a separate guidescope that has a high enough magnification up to x 500, which is really far too high for proper observing. However, guidescopes only work with refracting and reflecting telescopes but not with Schmidt-Cassegrains and Maksutov Cassesgrains. This is because the mirror in catadioptric telescopes tends to move slowly as the telescope tilts while following a star. This creates image movement that the guidescope does not detect.

One way to get around this problem is to use an off-axis guider. This intercepts part of the main image that would not fall on the camera's image sensor, which means that the same image that is being photographed can be guided on. The difficulty with using an off-axis guider is locating a suitable guide star - more often than not there is no nearby star brighter than magnitude 12 in the appropriate place. But photographing open clusters and deep-sky objects close to the Milky Way makes it easier to find suitably bright guide stars compared to taking photographs of galaxies.

Because guiding is a tedious chore, most CCD cameras can actually do it for you. Such CCD cameras are called autoguiders, which can report on their accuracy as they go. Autoguiders replace the crosshair eyepiece. But there again how do you guide when taking a CCD shot? The same CCD cannot make guiding corrections whilst exposing an image simultaneously, can it? So, a second CCD is used in an off-axis guider. Or even by putting a single CCD to double use: to track and record at the same time. Such a set-up can take a short exposure, check for image shift, make another exposure, and shift as needed to match. Then the two images are combined, and so on over and over again.

Six Ways to Attach a Camera to a Telescope

There are six methods to attach a camera to a telescope for astrophotography. These are Piggybacking, Direct Coupling at the telescope's focus, Afocal Positioning of the camera, Positive and Negative Eyepiece Projection, and Compression Positioning of the camera. These methods will now be explained.

Piggybacking

This method of attaching a camera to a telescope does not involve the camera actually taking pictures through the telescope. Instead, the camera sits on the telescope and takes a long exposure through its own lens while the telescope tracks the stars. This method can give superb images of comets and the Milky Way Galaxy.

Direct Coupling

This is the easiest way to attach a camera to a telescope. The telescope does not need an eyepiece and the camera does not need a lens. The telescope goes onto the camera. Refracting telescopes, Maksutov-Cassegrain and Schmidt-Cassegrain telescopes work well in this configuration. However, many Newtonian telescopes will not reach focus due to the fact that the image plane is not far enough from the end of the eyepiece tube.

Afocal Attachment

This method will work with any telescope and any camera - even with compact digital cameras and video cameras. This is a very easy method to use and is practically foolproof. The camera lens is set at maximum aperture (that is the lowest f-stop number) and focused at infinity. Do not use autofocus. The camera is then held in place with a bracket or simply placed on its own tripod. A bright object such as the Moon is best for this method as the camera does not track with the telescope. In fact, because the Moon is so bright it is quite easy to simply hand-hold the camera as the exposure will be short.

Positive Eyepiece Projection

This method gives a larger magnification than by Direct Coupling. An eyepiece is attached to the telescope, but the camera, behind it, has its lens removed. The downside of this method is that images tend to be sharp only at the centre, which means this may not be good enough for shots of the Moon. However, on the plus side, positive eyepiece projection will work with any telescope, Newtonians included.

Negative Eyepiece Projection

This method is very similar to Direct Coupling but a teleconverter or a Barlow lens is added for extra magnification. The benefits of this method compared to positive eyepiece projection, is that images of the Moon remain sharp throughout.

Compression Positioning

In this method of attaching a camera to a telescope, a focal reducer (telecompressor) is used. A focal reducer is basically the opposite of a Barlow lens - it has a convex lens to make the image smaller and brighter, reducing the focal length and f-ratio, hence the term compression. This is the method that is often used in deep-sky astrophotography.