Observation 
FAQs (Observation)| 1. Introduction 2. Instruments | 3. Observation |
1. IntroductionWhat is Amateur Astronomy?
Amateur astronomy is the practice of astronomy as a hobby. Astronomy is the science which is studying the stars, the planets, and the Universe
What Equipement Is Needed?
At first, your eyes only are needed, and being interested! Before considering any important purchase, just deepen your knowledge, visit websites, begin to look at the sky naked-eye, and see if you are really interested. The question of equipment should come later. About choosing an instrument, see the tutorial How to Choose an Instrument?
May An Amateur Astronomer Practise On his Own?
Yes. You may learn basics from websites, books and begin to observe
Are There Any Specific Fields of Observation or Activity Considered Mandatory?
No. Amateur astronomers are a wide and diverse population, ranging from people observing for their own pleasure, at different levels of dedication, to mirror and telescopes-makers or to people engaged in scientific research, some of them along with professional astronomers. Just see various websites or magazines' sections to see this range of interests!
Is There Any Basic Set of Knowledges Required, When One Boasts to be An Amateur Astronomer?
Generally, yes! Skills to master one's way in the night sky or to understand how the sky works seem indispensable. One may consider that the following list needs to be correctly mastered by any person considering itself like a amateur astronomer. A basic knowledge of the night sky -the sky at night during all the four seasons of the year, those constellations and their main stars; a basic knowledge of the main lunar relief features; the understanding of the fundamental celestial mechanisms, like the concept of celestial sphere, the one of the ecliptic and the apparent motion of the planets, or the mechanism of the seasons, etc. Basics about the current state of cosmology today, with the current model of the Big Bang, and about the main structures of the Universe (like what the galaxies or our Milky Way Galaxy are, or the solar system, etc.) Some basics too about the astronomical telescopes are too part of the minimum which a amateur astronomer is to master! More advanced notions, on the other hand, are not fundamentally necessary as they should be function only of the personal engagement you have into the hobby. The more you'll advance into the practice -be it general- of amateur astronomy, the more you will have to deepen the knowledges we just mentioned above. Or, should you get specialized into one domain of observation, you'll have to acquire more specialized knowledges relative to that domain! Thus, an observer who will have specialized into the planetary observation of one given planet, through astrophotography, for example, obviously will have to more deeply master all what is about the solar system, and that planet especially alltogether with the techniques of the astrophotography!
May An Amateur Astronomer Join Amateur Astronomers Groups?
Yes. Such groups like astronomy clubs or astronomical societies may help you as a place where you will meet other afficionados, get a bulletin, benefit from the possible club's amateur observatory or instruments lending, and of the synergy of such institutions. Any amateur astronomer however will assess by itself however what's the level of commitment he wants to be involved with, with a group
May an Amateur Astronomer Participate into Scientific Level Researches?
Yes. It has been a tradition that some sectors of amateur astronomy has always linked amateurs and professionals, like variable and binary stars observation. Although such fields are being gradually modified due to the new digital techniques, these same techniques are opening new fields of collaboration between pros and amateurs like photometry of exoplanets transits, of active galaxies, and of eclipsing binaries; or in the field of spectroscopy (stars, planetary nebulae, planets). The use of PCs also brings to the concept of 'Citizen science' through which amateurs are sifting across vast amounts of data, in numerous fields, that professional astronomers can't afford to
Can a Amateur Astronomer Turn Into a Professional Astronomer?
Yes! Function of his age only however! A youngster, obviously, who will have developed an interest in amateur astronomy and found that a career in professional astronomy would fit him, will just have to turn his curriculum in that direction and eventually acquire a degree in professional astronomy. The sole difference with the amateur astronomers, generally, is that his studies in science and maths will likely swiftly turn his pratice of amateur astronomy into something already scientific and academic, instead of a pure amateur practice! Amateur astronomers who are more advanced in age and who did fit into a career which is not related to professional astronomy have about no chance, usually, to turn a professional astronomer -a change of career and a new formation excepted, of course! Amateur astronomy, young, may trigger too an interest into becoming an astronaut, for example
Could you Tell me More About the History of Amateur Astronomy?
The distinction between professional, and amateur astronomy was essentially a 19th century fact. And barely as amateur astronomers of this time were more advanced dilettantes than amateurs in the proper sense of the word. That was due to the high price of optical instruments. The concept of amateur astronomy, as the term then was 'popular Astronomy' likely was launched in France by Camille Flammarion around 1880 the younger brother of whom was the founder of the Flammarion Editions and the both brothers being politically progressive. With the founding of the Société Astronomique de France (SAF) by 1887, a society of advanced amateurs, Flammarion also made available to the SAF's members a equatorial telescope of 108mm, then a Mailhat telescope of 190mm. Amateurs, according to Flammarion, could contribute to science by addressing areas that professional astronomers, like double stars, variables, had to neglect. These views lasted up to 1945 and market prices for small personal astronomy instruments remained at a high level. However, very good introductory books existed at the time already. After 1945, the consumer society allowed easier access to amateur instruments and, particularly, in the years 1960, Japanese instruments arrived on the market. Then came, in the years 1970, American instruments including the famous type Schmidt-Cassegrain, illustrated by the Celestron brand and used in amateur astrophotography. Then the market of the amateur instruments, with a return of the Japanese, diversified and probably improved. Finally, with the advent of computer science and digital imaging, a recent chapter in the history of amateur astronomy opened. Some amateurs are now even venturing into spectroscopy and radio astronomy. The collaboration between professional and amateur astronomers is a feature of contemporary amateur astronomy, with amateurs continuing to occupy fields that are neglected, for cost reasons, by professionals. More recently, the American concept of 'citizen science' developed, like also environmental concern among astronomy clubs, like the question of dark skies, nature protection, or nocturnal fauna. Since the beginning of the millennium, it is China and Taiwan -- a Taiwanese company repurchased Celestron in 2005, for example -- which became market leaders. At last, worth of note is that the amateur construction of telescopes, or 'Amateur telescope making,' ATM, kept on
2. InstrumentsHow do Astronomical Telescopes Work?
Astronomical telescopes all work on the same principle: a main optical device is producing at a distance a magnified image of the object observed. An eyepiece there -an eyepiece is a secondary optical device- is further magnifying the image. The final power, or magnification, is a ratio of the focal length of both the primary and the eyepiece optics. The focal length of an optical device is the point where the image of the object observed is formed and in focus. A given telescope yields various magnification values depending on what eyepiece is used. A telescope with a focal length of 700 mm used with a 20 mm eyepiece yields a power of 35 x as the same telescope used with a 10 mm eyepiece yields a power of 70 x. Manufacturers generally offer an eyepieces' range sufficient to give each telescope about 6 or 7 magnification values. The same is true of the telescopes and the eyepieces ranges purchased independently as independent manufacturers are working on such basis too. The important in this latter case is to worry that the telescope's eyepiece holder features one of the eyepieces's standard diameters that is, mostly, 1.25" or 2". This question is of importance too for a further evolution of your telescope as you will then add it with more accessories. Most of accessories (for astrophotography e.g.) also features these two diameters
What are the Main Types of Astronomical Telescopes?
Astronomical telescopes mainly sort into refractors, newtonian reflectors, and catadioptric Schmidt-Cassegrains which are a mix of both. Refractors are tubes with a lens at their aperture. The lens is forwarding the light to the other end of the tube where an eyepiece is used to further magnify the object. Newtonian reflectors are an open tube at the bottom of which a reflecting mirror. The mirror is sending the image towards the eyepiece through a secondary mirror. The eyepiece location is at the top of the tube, at a right-angle of the instrument. In catatadioptric Schmidt-Cassegrains telescopes -Schmidt-Cassegrains telescopes (SCTs)- light is reaching a primary reflecting mirror through a corrective lens located at the entry of the instrument. The light is reflected from the primary mirror towards a secondary which sends the image further, through a hole in the primary, to the eyepiece. Dobsonians are newtonian reflectors. Their pecular name comes from their mount only
What's the Trend Today as Far as Astronomical Telescopes are Concerned?
As the mainstream trend one or two decades ago were long-focal/small-field Newtonian reflectors and high-end Schmidt-Cassegrains, the first part of the equation has now been replaced by short-focal/large-field refractors. Such instruments are chosen as they are good at deep-sky objects, able to planetary observation with appropriate additional tools like barlows or short focal eyepieces, and as they are easy to transport and to set up. Schmidt-Cassegrains are remaining high-end instruments -due to their price- but still remain choice instruments when a life-long investment is considered as they are best at astrophotography. High-end refractors exist too with aprochromatic lenses for best possible images. Their price is high. On the other hand, as a decade ago, 10" were a dream for most amateurs, a trend today is to large telescopes. for a detailed tutorial about choosing an instrument, see the tutorial How to Choose an Instrument?
Are Binoculars Useful for Astronomical Observation?
Due to the relief effect, the deepness they are providing, and their large apparent field, binoculars are a good initiation tool or they may be used too by advanced amateurs like a relaxation instrument or like an additional tool. Some dedicated large binoculars are used for comet-hunting
Do Astronomical Telescopes Yield Inverted Images?
Yes. To avoid light dispersion and an alteration of the optical quality, most astronomical telescopes are reverting the picture of the object observed. Refractors and SCTs are yielding an upside-down image as Newtonians and Dobsonians are rotating the image depending on the eyepiece's angle relative to the vertical. Should the user want to use its astronomical telescope for terrestrial purposes, he will have, if possible, to use an optical device, called an "erect-image" or a "correct-image prism diagonal", which will gives back the picture its normal look. Unfortunately such erecting prisms do not work with Newtonians (hence with Dobsonians). Erecting prisms usually come at a 45° angle. Binoculars are yielding normal images and may be used for terrestrial or astronomical purposes. Used for astronomy they do not revert the image of the object
What is a Star Diagonal?
The configuration of a telescope or the angle of the object observed above the horizon may render difficult the use of an eyepiece directly in the axis of the light path. If you want to use your SCT looking at the zenith or to look through your refractor mounted on an equatorial mount you will find difficult to use the eyepiece in the axis. That's why an optical device called a "star diagonal" is often used along any telescope. A star diagonal is basically a mirror -or a prism- which is sending the image at an angle of 90°. Looking at an object at the zenith will become more comfortable! On the other hand a star diagonal will add to the fact that astronomical telescopes are reverting the image. Using a star diagonal with an SCT will reverse the image back upside-down as it will revert it left-to right!
What is a Barlow Lens?
The power of an astronomical telescope is determined by the focal length of the eyepiece used, related to the focal length of the instrument. A Barlow lens is an optical device -a tube and lenses- which is acting on this ratio. A Barlow multiplies, usually by 2 (or a larger value), the power yieled by a given eyepiece. Should you use an eyepiece of 10 mm on a telescope with a focal length of 700 mm you are getting a magnification of 70 x. Using a 2 x Barlow, the same configuration will give a power of (70 x) x 2 = 140. Until recently Barlows were discarded by amateur astronomers as they were seen as degrading the image's quality. They gained more consideration now as they are a way to use short-focal/wide-field refractors for planetary purposes
What is a Telescope Mount
Strictly a telescope's mount is the mechanical device which bears the telescope and allows to point it to the sky. Usually, it's the mechanics found at the top of the tripod of the instrument. Telescopes' mounts come in various types
What is a Tripod?
Strictly a tripod is the three-legged device which bears the mount of the telescope. The mount, then, bears the telescope. A pier is in some cases an alternative to a tripod. The essential quality of this part of the equipment is that it has to be sturdy to avoid any vibration destructive of the image's quality and to damp them out the most quickly possible
3. ObservationLooking at the Night Sky for the First Time, What is Seen?
Constellations, planets, and possibly the Milky Way provided your obervational location is dark enough. Constellations and planets are the basis of astronomy. Constellations are apparent closenesses of stars which are seen in perspective to be gathered into recognizable groups, as planets are our sister-planets in the solar system and are seen at different locations in the night sky all year long. Simply said, our night sky, at 4,000 stars visible naked-eye and the Milky Way, mostly is what we see from our Milky Way Galaxy, our gathering of stars, with our Sun, in the Universe. The objects to observe in the night sky are, first, the planets, asteroids and comets, which are the world of our solar system. Then the constellations, which allow to spot celestial objects, binary stars, variable stars, nebulae, star clusters, and globular clusters, or the world of the stars of the Milky Way Galaxy. And, eventually, the galaxies and the galaxies clusters located outside the Milky Way Galaxy, which constitute the Universe at large
What Is the Celestial Sphere?
The celestial sphere is the night sky. All space, stars, and planets surrounding us are seen at the same apparent range independently of their real distance from us. The celestial sphere is the materialization of this appearance helping to figure out the sky and to give coordinates to celestial objects
Where are Planets to be Found?
Any planet is found along what is called the ecliptic. The ecliptic is a fictitious line seen along the sky where planets's motion is seen to take place due to almost all planets of the solar system being in about the same plane. Hence seen from Earth, this plane is seen on the celestial sphere. Due to their more or less proximity to the Sun, some planets are just seen after sunset or before sunrise, like Mercury and Venus, or all night long like any planet starting at Mars
What Are the Planets of the Solar System?
Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, in this order. Earth is found after Venus
What are the Satellites of Jupiter?
The satellites of Jupiter are the four satellites of the gas giants mostly seen from Earth beginning in smallest instruments. These four satellites are seen each night moving around Jupiter. It is Galileo Galilei using the first astronomical instruments in the 17th century who first saw them, hence they are called too the Galilean satellites of Jupiter. They are, in this order from Jupiter: Io, Europa, Ganymede, Callisto
What is Astrophotography?
Observations through an instrument may be recorded through hand-drawing and/or a describing text, or through photography. Astrophotography is an usual field of amateurs activity and was mostly practised until recently with film and SLRs cameras. The advance of digital imagery is making that many amateurs now are using digital tools. Due the high price of such cameras and to the variety of available devices, a natural categorization of sort appeared between high-end CCDs, webcams, usual and SLRs digital cameras. see more at "Astrophotography"
