Preface

‘It is a beautiful, delightful sight to behold the body of the moon’

GALILEO GALILEI

Astronomy has always been a passion of mine, as I have always been fascinated by the majestic objects present all around us in the night sky, many of them going unseen by most people. It was the astrophotography element which revealed this hidden world and I soon became hooked when I realised how much detail could be captured using equipment in the backyard. I started with deeper sky astrophotography but quickly developed an appreciation for Earth‘s closest satellite, the Moon. This lunar neighbour of ours is quite often underappreciated and almost taken for granted as a featureless rock in the sky, but the reality is quite the opposite. As you start observing the Moon, you immediately see a world which you have never seen in such exquisite detail before. The more you view the Moon, the more intriguing the geological diversity and variety of features become. When you view the different craters, seas, mountains, rilles and rays you will discover that there is much more to the Moon than meets the eye.

Capturing these lunar details using modern astrophotography techniques will reveal the exquisite detail of objects which are impossible to view with the unaided eye, and once you master the imaging techniques, it is self-inspiring, educational and overall a great way to learn about photography.

I hope the book will inspire you to take up astronomy and more importantly to try your hand at astrophotography which initially may seem quite daunting, especially with so many technical terms involved in the learning process. Once you understand the terms, the steps involved and the technology, the reality is that even some of the most basic equipment will give you outstanding results.

As well as the photographic aspect, the book will also assist you in navigating the Moon, identifying features and understanding the variations in geology and the formation of different lunar features visible through your telescope, and you will be surprised at the level of detail which your equipment can see. It took a lot of research and trial and error to find a technique which worked for me to capture and process the images in fine detail. Once I started down the route of lunar photography, it quickly became evident that capturing the image is only one aspect of producing a beautiful picture; as image processing also has a significant influence on the outcome.

When learning about lunar astrophotography, I quickly discovered that there was a distinct lack of resources in all areas, including the Moon’s geological features, the technical aspects of lunar photography and the most challenging of all: image processing. This made it very difficult for me to break into astrophotography. Online resources are available and online forums may be helpful if you have specific questions, but you may find information is quite fragmented and it is not always obvious which are the right questions to ask. The lack of information is one of the main reasons I decided to write this book.

Initially, however, there are some useful resources to consider. For example, you may have a local astronomy shop which would be able to advise you on equipment for observing the Moon within your price range. I found this resource was beneficial and an excellent place to start, although astronomy shops are becoming less common. Another option would be your local astronomy club which would be happy to advise you and potentially lend out equipment for you to test before you purchase your equipment.

The purpose of this book is to provide jargon-free information on all the processes involved in imaging the Moon and I hope it will be invaluable to anyone starting this hobby. This book is aimed at beginners, amateur astronomers or anyone interested in learning about the Moon, and it will provide advice for finding and imaging lunar features. A basic understanding of camera operation and photographic terms is assumed.

The first part of the book provides a general outline of the hobby, including the use of equipment, capturing images, image expectations and image processing which is a very important and sometimes overlooked aspect. I have written the processing steps as an easy-to-follow visual, step by step guide for beginners. Overall the book contains all the information you will need for lunar photography and I hope it will inspire you to get out your camera and telescope and start observing the Moon. The book does not recommend any specific telescopes as it focuses primarily on the photographic aspect. However, most telescopes are suitable for lunar photography and the principles of photography discussed here can be applied to other telescopes. The images in the book were captured using standard equipment.

The second part of this book highlights some of the more popular lunar features and shows you how to find them on the surface, including a few detailed facts about each one. Some of the features are easy to see but others are more challenging. See how many you can find!

I want to express my thanks and gratitude to the people who made this book possible with their support and assistance. I must start by thanking my wife Melanie for her encouragement and patience throughout the whole process, especially with the hours spent behind the telescope! My children Louis and Tom for their dedication and help. A special thanks to Gary Harrop for his excellent eye for details and the time taken to help with my work.

Understanding the workings of the Universe is awe-inspiring, especially when you look into the depths of space on a clear night you realise how insignificantly small we are on the grand scale of the Cosmos. You can learn a lot from looking beyond the Earth and observing galaxies, nebulae, planets and our closest neighbour the Moon all show the wonders of nature. As you would probably expect, most of the exquisite detail is hidden from the view of the unaided eye and requires equipment to reveal this hidden world.

Using a telescope or a pair of binoculars would be a natural place to start when taking a closer look at astronomical targets and many astronomers are keen visual observers, one thing to realise when starting in astronomy is that looking through a telescope will not reveal the outstanding detail as seen in magazines and books. The view through the eyepiece will sometimes leave new observers a little disappointed compared to their expectations, as the images you see in print or on the Internet are created using astrophotography techniques and not what you see visually through the eyepiece. As digital photography advances and becomes available at a reasonable cost, it is relatively inexpensive to purchase equipment for capturing highly detailed images.

The Moon is enigmatic, and people have observed the Moon waxing and waning for millennia with the shadows on its surface developing imaginations, the man in the Moon being a common notion. The Moon formed approximately 4.5 billion years ago, the leading theory suggests that a Mars-size object collided with the Earth and the resulting debris combined to form the Moon we see today, and it has orbited the Earth ever since. Throughout its history the Moon has been bombarded with space debris and become pockmarked with craters to produce the lunar landscape we are familiar with. Many of these craters and more significant impact basins occurred during the late heavy bombardment period which was a period with an unusually high rate of collisions during the Solar System’s early history. Unlike the Moon, the tectonic action and erosion on Earth cleared the planet of its pock-marked appearance over geological time, but as the Moon has no atmosphere or tectonic activity, the lunar surface holds the history of these past bombardments like a geological time machine. However, the Moon’s surface is not immune to degradation as minor changes have occurred over geological time. You can observe this degradation by comparing the more recent impact craters such as Copernicus and Tycho with older craters, these younger impact craters are very noticeable on the lunar surface as they have prominent impact rays compared to their older counterparts which have had their impact rays degraded over time. This degradation is due to a combination of processes including bombardment by micrometeorites, thermal cycling (extreme temperature fluctuations), and solar weathering due to charged particles from the Sun.

The Moon rotates almost exactly once every time it orbits the Earth and is called synchronous rotation. Due to this effect, the same hemisphere always faces Earth. However, there are slight differences in features which you can see due to the Earth’s tilt and its elliptical orbit. This allows you to view more of the Moon at certain times. This more expansive view in both longitude and latitude is known as Lunar libration, and you can see about fifty-nine per cent of the lunar surface from Earth.

Technology has only relatively recently become developed enough to see features you could only dream about 100 years ago. The NASA Lunar Reconnaissance Orbiter has revolutionised the understanding of the Moon with a camera resolution down to metres; it is even possible to view the lunar landing sites. Backyard telescopes can at best resolve features down to approximately 1km, but this far exceeds technology of only fifty years ago. Historically probes had to be sent to the Moon to see details which we can now see from our backyard.

The Moon is bright compared to most other astronomical targets such as galaxies and nebulae; these deeper sky objects generally require much longer exposure times to capture the exquisite detail and a more sophisticated imaging system such as guiding equipment to counteract the movement of the Earth. Some long exposures can run into tens of minutes per exposure, and it is usual to stack multiple frames together to produce a gratifying photo. You can, therefore, appreciate how a typical imaging session for a deep sky target can take a full night or even multiple nights to produce enough data to process an image. Stacking is a process of adding many images together using software to produce a final high-quality image. For example, rather than taking one sixty minute exposure, it is more reasonable to use 10 x 6 minute exposures and stack the images together to produce a detailed picture. The Moon is generally considered a nuisance and a source of light pollution for deep sky astrophotographers. However, we lunar photographers like the exact opposite and enjoy observing the Moon when it is high in the sky.

Imaging the Moon is extremely satisfying as you can capture the details without the need for long exposures and there is no requirement for hours of data, as the Moon is so bright you can capture enough data in minutes to process and produce a beautiful image. It is quite possible to navigate and image the full surface of the Moon within a single evening.

Although the Moon is bright and relatively close to the Earth, viewing and imaging the Moon can be challenging. For example, the weather and cloud cover can be frustrating, but more importantly, the ‘seeing’ needs to be kind to make out the finer lunar details. The ‘seeing’ which astronomers refer to is the change in clarity of the image caused by atmospheric distortion and this is vividly evident when viewing the moon through a high-powered telescope as the image can appear to wobble intermittently, reducing the sharpness. It is this effect which will severely impact the quality of the final picture. The amount of atmospheric turbulence present determines the quality of the ‘seeing’, the cause of which can be attributed to warmer air meeting cooler air and observing over houses and buildings may also be a source of heat, for example. The colder winter months generally provide better observing conditions than the summer months as the cooler atmosphere contains less moisture, and the thermals caused by elevated surface temperatures are less pronounced. Also, timing your observations when the Moon is highest in the sky will help reduce the issues with ‘seeing’ as the light has less atmosphere to pass through. The thinner atmosphere helps to reduce the effects of atmospheric distortion and to improve the ‘seeing’. You can easily see the effect the atmosphere has on the light by looking at the Moon near the horizon. You will observe that it has a blurry red/yellow hue as the atmosphere blocks the shorter wavelengths. Compare this view with the Moon high in the sky; it will have a white and crisp appearance.

Filters can be used to significantly reduce the effect of poor atmospheric conditions. For IR sensitive cameras IR pass filters 850nm are commonly used and the clarity can be exceptional. However, the drawback is that the filter inhibits the visible light spectrum and a colour camera becomes a mono camera. One other highly effective method to overcome ‘seeing’ issues is to use a high frame rate camera to capture thousands of frames, sort out the best quality ones using designated software and stack these to produce a final image. This approach takes advantage of the millisecond patches of clarity and builds an image from it. We will discuss the use of high frame rate cameras and stacking in greater detail later in the book.

This book can be used as a practical guide to help those who want to start learning lunar astrophotography or those who want to become acquainted with our lunar neighbour a little better. The book is an essential guide to understanding lunar features, capturing images, stacking images, identifying features and processing the images to bring out the best of your captures. As well as learning these necessary capture and processing techniques, you can also use this book as a guide to locate different lunar targets; these targets are a selection of some of the most popular, notable and unusual features to observe or photograph. I have briefly described each feature and highlighted how easily they can be found and the equipment which you will probably require. Some features are easy; others are quite challenging and may require perseverance. To make it easier for you, I have highlighted the region of interest on a photo combined with a close-up image of the feature.

Technical Terms

A description of some of the technical terms used in the book:

Albedo – Proportion of reflected light by a surface

Basin – Large impact formations with diameters generally greater than 300km and with multiple impact rings

Clair-obscur effect – A visual effect of reflected light and shadows creating recognisable objects

Dorsa/Dorsum – Wrinkle ridge (Dorsum) and wrinkle ridges (Dorsa) created by contracting lava

Ejecta – Material that is thrown out as a result of meteoritic impact

Foreshortening – A visual effect on the perspective of an object caused by the angle of vision, e.g. craters can look elongated when seen towards the edge of the Moon

Graben – A depressed block of crust bordered by parallel faults

Libration – Variation in the visible side of the Moon allowing more than half the surface to be viewed

Limb – The edge of the visible surface of the Moon as viewed from Earth

Mons/Montes – Mountain / Mountains

Mare – Sea or large plain of hardened basaltic lava, created by huge impacts in the early history of the Moon and generally related to basin formation

Rima/Rimae/Rille –Long, narrow channels

Rupes – Cliff, scarp or fault

Vallis – Valley

Sinus – Bay

Terminator – The boundary between the light and dark sections of a lunar phase