Nebulae – Interstellar clouds of dust and ionised gas. Distance: 700 to several thousand light-years.
Atmosphere – Optical phenomena occurring in Earth’s atmosphere.
Galaxies – Gravitationally bound systems of stars, gas, dust and dark matter. Distance: hundreds of light-years to billions of light-years.
The Moon – Earth’s only natural satellite; about the size of Australia. Distance: 1.3 light seconds.
The Sun – A nearly perfect sphere of hot plasma fuelled by nuclear fusion. About 100 times the diameter of Earth. Distance: 8.3 light minutes.
Planets – Planetary bodies orbiting a star that are of sufficient size to be rounded by their own gravity but not massive enough to cause thermonuclear fusion. Distance: between 0.3 light seconds (Mercury) and 39.44 light seconds (Pluto).

Comets – Small, icy solar system bodies that release gas when approaching the Sun. Period ranges from a few years to several million years.
Wide Field – Large areas of the sky photographed with very short focals.
Spectroscopy – The interaction of matter and electromagnetic radiation as a function of its wavelength.
Eclipse – An event that occurs when an astronomical body is temporarily obscured by passing in the shadow of another body situated between itself and the observer.
Asterisms – A visually obvious collection of stars that resemble a known pattern.
Astrophoto Setup – Optics, mounts, cameras, filters and auto-guiding.
ESO – La Silla, CL – The European Southern Observatory in La Silla, Chile
Star Clusters – Groups of stars that are gravitationally bound together; they can be globular clusters (old, millions of stars) or open cluster (young, a few hundred stars). Distance: hundreds to billions of light-years..
Satellites – Man-made objects orbiting the Earth. Standard geostationary orbit is about 35’000 km above the equator.


Astrophotography is the imaging of planets, nebulae, galaxies, star clusters and generally everything in the sky, including the Sun and Moon. It has the peculiarity of rendering visible objects which are too dim to see with the naked eye (galaxies and nebulae), thanks to long exposure times and the summing-up of several shots (known as “stacking”).

Astrophotography is dependent upon cloud cover, or more precisely upon the lack thereof, as well as on light pollution. London would be a good example of very poor conditions (large, brightly lit metropolis with abundant rainfall), but my location can also be described as “shit”: 3o% clear skies on average with severe light pollution.

Yearly cloud cover for a smallish city (200k inhabitants) at mid-Northern latitudes. Far from ideal.