We now discuss the techniques and instruments used by astronomers observing at wavelengths shortward of 91.2 nm. Temperatures in excess of 105K, or non-thermal mechanisms, are required if significant emission is to occur at these wavelengths, and thus we may consider ourselves dealing with high-energy astronomy. Extreme ultraviolet (100 —10nm), soft X-ray (10 —1nm), X-ray […]
We have already emphasized, in the introduction to this chapter, the great value of launching telescopes into space. This section concentrates on the infrared, optical and ultraviolet wavebands. It is unlikely that radio telescopes will be placed in orbit in the near future, owing to the enormous size necessary for reasonable angular resolution, but several […]
The results of many of the space missions to the Moon and planets have already been detailed in the chapters on the Solar System. In the present section we outline some of the methods by which these results were obtained. The pattern of study of a planet by subsequent spacecraft generally parallels that applied to […]
The orbit of an artificial satellite about the Earth, or any other body, can be treated mathematically in exactly the same way as the motion of binary stars, or the planets. The orbit is an ellipse obeying Kepler’s laws. The period of a satellite grazing the Earth’s surface (if it were possible) is 84.3 minutes, […]
The science of space astronomy is relatively young, and yet it has given astronomers some of the most exciting findings about our own Solar System and the high-energy Universe beyond. Were it not for the development of a camera that could be operated across 200 million km of interplanetary space we would know hardly anything […]
Once the telescope has been acquired, it may well be necessary to construct a simple observatory or telescope housing. Telescopes are not elegant additions to domestic furnishings, and one with an. aperture above 150mm is likely to be awkward to manoeuvre. Local climatic conditions will to some extent dictate the type of observatory to be […]
The first decision must be: which type of telescope – reflector or refractor? The advantages and disadvantages can be summarized briefly as follows: Newtonian reflectors produce images that are free of chromatic aberration (false colour). They are relatively cheap, and it is fairly easy to re-align the optical system. Among the disadvantages are the need […]
Binoculars can be used for everyday observing, such as sporting events and nature study, as well as astronomy. They are classified according to their magnification and the diameter of the objective. A 10 X 50 pair magnifies 10 times (100 areas) and has objective lenses 50mm in diameter; note, however, that in cheaper binoculars the […]
The night sky Anyone with a keen interest in astronomy may want to acquire their own telescope. There is a large range of good telescopes on sale in most countries, with Europe and North America being particularly well supplied. The amateur astronomer can use a great variety of instruments and techniques, and even build an […]
Another coordinate system is sometimes preferred when astronomers are studying the structure of the Galaxy. This system uses the plane of the Galaxy as the reference plane and the centre of the Galaxy as the arbitrary reference point. The coordinates are both expressed in degrees. They are the GALACTIC LONGITUDE (1) and the GALATIC LATTITUDE […]