Observing the Night Sky

Whether you're observing as a beginner or as an experienced astronomer, amateur astronomy is becoming increasingly accessible. What would have been out of most people's price ranges but 20 years ago can now be bought for very reasonable prices. Observing the night sky opens up a new window to the beyond and now is as best a time as ever to get involved.

What can I see with my equipment?

Using simple, relatively cheap equipment, you can see a wide range of different astronomical objects. Even through the use of binoculars, brighter and/or larger objects such as large galaxies can be observed with quite some detail. A basic refracting telescope will be capable of observing the planets in much detail, as well as many of the galaxies and clusters. A reflecting telescope is generally a step up in terms of cost, however it is worth considering as the detail and contrast obtained can lead to some spectacular observations.

Commonly visible astronomical features include constellations and asterisms - collections of stars which form patterns, planets in the Solar System, star clusters, nebulae and galaxies.

How to Observe the Sky

The first things to know when beginning to observe the sky are:

  • How objects are located in the sky.
  • The practical and safety considerations which have to be made when observing.

Firstly, objects are located by a system of co-ordinates on an imaginary sphere around the earth known as the celestial sphere. The horizontal coordinates are known as right ascension (RA, measured in hours from 0 h to 24 h), the vertical coordinates are known as declination (dec, measured in ° from -90° to +90°). The zenith of an observer is the point directly above their head, equal to 90° - the observer's latitude. The meridian of the observer is the line through from RA 0 h, dec 0° to RA 12 h, dec 0°, passing through the zenith.

The practical considerations of observation tend to be reasonably simple things such as the weather and climate conditions, however whilst observing, it is important to be mindful of some additional considerations. From Earth, it is easy to assume that stars which appear near to one another are actually near to one another, however in practice this is rarely ever the case. This is particularly well demonstrated in the difference between double stars and binary stars. Double stars appear close in space, however are actually very far apart, whereas binary stars appear close because they are part of the same system, orbiting the same point.

James Gooding, 2017

All image credits go to NASA (and respective centers/universities)