Everything about Amateur Astronomers totally explained
Amateur astronomy, a subset of
astronomy, is a
hobby whose participants enjoy studying and observing celestial objects.
Overview
The amateur astronomer is one who doesn't depend on the field of astronomy as a primary source of
income or support, and doesn't have a
professional degree or advanced academic training. Many amateurs are beginners, while others have a high degree in astronomy and often assist and work alongside professional astronomers.
Amateur astronomy is usually associated with viewing the
night sky when most celestial objects and events are visible, but sometimes amateur astronomers also operate during the day for events such as
sunspots and
solar eclipses. Amateur astronomers often look at the sky using nothing more than their eyes, but common tools for amateur astronomy include portable
telescopes and
binoculars.
People have studied the sky throughout history in an amateur framework, without any formal method of funding. It is only within about the past century, however, that amateur astronomy has become an activity clearly distinguished from professional astronomy, and other related activities.
Amateur astronomy objectives
Collectively, amateur astronomers observe a variety of celestial objects and
phenomena. Common targets of amateur astronomers include the
Moon,
planets,
stars,
comets,
meteor showers, and a variety of
deep sky objects such as
star clusters,
galaxies, and
nebulae. Many amateurs like to specialise in observing particular objects, types of objects, or types of events which interest them. One branch of amateur astronomy, amateur
astrophotography, involves the taking of photos of the night sky. Astrophotography has become more popular for amateurs in recent times, as relatively sophisticated equipment, such as high quality
CCD cameras, has become more affordable.
Most amateurs work at
visible wavelengths, but a small minority experiment with wavelengths outside the visible spectrum. The pioneer of amateur radio astronomy was
Karl Jansky who started observing the sky at
radio wavelengths in the 1930s, and interest has increased over time. Non-visual amateur astronomy includes the use of
infrared filters on conventional telescopes, and also the use of
radio telescopes. Some amateur astronomers use home-made radio telescopes, while others use radio telescopes that were originally built for astronomy research but have since been made available for use by amateurs. The
One-Mile Telescope is one such example.
Common tools
Amateur astronomers use a range of
instruments to study the
sky, depending on a combination of their interests and resources. Methods include simply looking at the night sky with the
naked eye, using
binoculars, and using a variety of
telescopes of varying power and quality, as well as additional sophisticated equipment, such as
cameras, to study light from the sky in both the visual and non-visual parts of the
spectrum. Commercial telescopes are available and used, but in some places it's also common for amateur astronomers to build (or commission the building of) their own
custom telescope. Some people even focus on
amateur telescope making as their primary interest within the hobby of amateur astronomy.
Although specialised and experienced amateur astronomers tend to acquire more specialised and more powerful equipment over time, relatively simple equipment is often preferred for certain tasks. Binoculars, for instance, although generally of lower power than the majority of telescopes, also tend to provide a wider
field of view, which is preferable for looking at some objects in the night sky.
Amateur astronomers also use
star charts that, depending on experience and intentions, may range from simple
planispheres through to detailed charts of very specific areas of the night sky. A range of
astronomy software is available and used by amateur astronomers, including software that generates maps of the sky, software to assist with astrophotography, and software to perform various calculations pertaining to astronomical phenomena.
Amateur astronomers often like to keep records of their observations, which usually takes the form of an
observing log. Observing logs typically record details about which objects were observed and when, as well as describing the details that were seen. Sketching is sometimes used within logs, and photographic records of observations have also been used in recent times.
The Internet is an essential tool of amateur astronomers. Almost all astronomy clubs, even those with very few members, have a web site. The popularity of CCD imaging among amateurs means large numbers of web sites written by individuals about their images and equipment. Much of the social interaction of amateur astronomy occurs on mailing lists or discussion groups. Yahoo groups and Google groups host numerous astronomy lists. A great deal of the commerce of amateur astronomy, the buying and selling of equipment, occurs online. Many amateurs use online tools to plan their nightly observing sessions using tools such as the
Clear Sky Chart.
Common techniques
Many methods are used in amateur astronomy to locate items in the sky, but most are variations of a few specific techniques.
Star hopping
Star hopping is a method often used by amateur astronomers with low-tech equipment such as binoculars or a manually driven telescope. It involves the use of maps (or memory) to locate known
landmark stars, and "hopping" between them. Because of its
simplicity, star hopping is a very common method for finding objects that are close to naked-eye stars.
More advanced methods of locating objects in the sky include
setting circles, which assist with pointing telescopes to positions in the sky that are known to contain objects of interest, and
GOTO telescopes, which are fully automated telescopes that are capable of locating objects on demand (having first been
calibrated).
Setting circles
Setting circles are
angular measurement scales that can be placed on the two main
rotation axes of some telescopes. Since the widespread adoption of digital setting circles, any classical engraved setting circle is now specifically identified as an "analog setting circle" (ASC). By knowing the
coordinates of an object (usually given in
equatorial coordinates), the telescope user can use the setting circle to align the telescope in the appropriate direction before looking through its
eyepiece. A computerized setting circle is called a "digital setting circle" (DSC). Although digital setting circles can be used to display a telescope's
RA and
Dec coordinates, they're not simply a digital
read-out of what can be seen on the telescope's analog setting circles. As with go-to telescopes, digital setting circle computers (commercial names include Argo Navis, Sky Commander, and NGC Max) actually contain databases of tens of thousands of celestial objects and projections of planet positions.
To find an object, such as globular cluster
NGC 6712, one doesn't need to look up the RA and Dec coordinates in a book, and then move the telescope to those numerical readings. Rather, the object is chosen from the database and arrow markers appear in the display which indicate the direction to move the telescope. The telescope is moved until the distance value reaches zero. When both the RA and Dec axes are thus "zeroed out", the object should be in the eyepiece. The user therefore doesn't have to go back and forth from some other database (such as a book or laptop) to match the desired object's listed coordinates to the coordinates on the telescope. However, many DSCs, and also go-to systems, can work in conjunction with laptop sky programs.
Computerized systems provide the further advantage of computing coordinate precession. Traditional printed sources are subtitled by the
epoch year, which refers to the positions of celestial objects at a given time to the nearest year (for example,
J2005,
J2007). Most such printed sources have been updated for intervals of only about every fifty years (for example,
J1900,
J1950,
J2000). Computerized sources, on the other hand, are able to calculate the right ascension and declination of the "epoch of date" to the exact instant of observation.
GoTo telescopes
GOTO telescopes have become more popular in recent times as technology has improved and prices have been reduced. With these computer-driven telescopes, the user typically enters the name of the item of interest and the mechanics of the telescope point the telescope towards that item automatically. They have several notable advantages for amateur astronomers intent on
research. For example, GOTO telescopes tend to be faster for locating items of interest than star hopping, allowing more time for studying of the object. GOTO also allows manufacturers to add equatorial tracking to mechanically simpler alt-azmuth telescope mounts, allowing them to produce an over all less expensive product.
Because GOTO telescopes have become increasingly affordable, a new
type of beginning amateur astronomer has emerged, in that GOTO telescopes offer a form of instant gratification, sometimes allowing difficult objects to be found quickly without requiring the experience of learning to find them.
The GoTo debate
In the early 1990s, the amateur astronomy community engaged in some debate, usually light-hearted, about which method is superior. Some astronomers argued that beginning with the lower end of technology and using star hopping techniques is an excellent method of learning the sky, and that a good knowledge of the night sky can be advantageous for people who prefer simpler equipment with less calibration and setup time, and is therefore more versatile. Star hopping involves the use of printed media that's dependent on computer generated sources. The user prints out star maps at home or uses books,
atlases, and magazine articles that have computer generated graphics in them to aid in the quest to find an object.
GOTO telescopes, on the other hand, do make the hobby more accessible. They may be preferred by people who are more serious about studying objects, because less time and effort are required for finding objects when they're well prepared. But digital setting circle or go-to systems also provide touring functions whereby the user can set parameters such as
magnitude and class of object, and, for example, view a series of
planetary nebulae in
Cygnus. A user who has discovered that his list of close
double stars is impossible to view because of the seeing conditions can select an alternative viewing program within minutes. Many middle-aged and older amateur astronomers discovered that electronic pointing systems not only were convenient but spared them the difficult postures and associated aches and pains that go with pointing a telescope at
zenith (with the common straight-through finder) or near to the
horizon (on elevated mounts the finder can be out of reach). The explosion of astrophotography, in which a
webcam or
CCD camera is mounted on a telescope and downloads data to a nearby laptop, further enhanced demand for
robotic systems that would point the telescope while the operator could stay seated and set imaging parameters.
Imaging techniques
Amateur astronomers engage in many imaging techniques including
film and
CCD astrophotography. Because CCD imagers are linear,
image processing may be used to subtract away the effects of lightpollution, which has increased the popularity of astrophotography in urban areas.
Scientific research
Scientific research is most often not the
main goal for many amateur astronomers, unlike professional astronomy. Work of scientific merit is possible, however, and many amateurs successfully contribute to the knowledge base of professional astronomers. Astronomy is sometimes promoted as one of the few remaining sciences for which amateurs can still contribute useful data. To recognise this, the
Astronomical Society of the Pacific annually gives
Amateur Achievement Awards for significant contributions to astronomy by amateurs.
The majority of scientific contributions by amateur astronomers are in the area of data collection. In particular, this applies where large numbers of amateur astronomers with small telescopes are more effective than the relatively small number of large telescopes that are available to professional astronomers. Several organisations, such as the
Center for Backyard Astrophysics
, exist to help coordinate these contributions.
Amateur astronomers often contribute toward activities such as monitoring the changes in brightness of
variable stars, helping to track
asteroids, and observing
occultations to determine both the shape of asteroids and the shape of the terrain on the apparent edge of the
Moon as seen from Earth. With more advanced equipment, but still cheap in comparison to professional setups, amateur astronomers can measure the light spectrum emitted from astronomical objects, which can yield high-quality scientific data if the measurements are performed with due care. A relatively recent for amateur astronomers is searching for overlooked phenomena (for example,
Kreutz Sungrazers) in the vast libraries of digital images and other data captured by Earth and space based observatories, much of which is available over the Internet.
In the past and present, amateur astronomers have played a major role in discovering new
comets. Recently however, funding of projects such as the
Lincoln Near-Earth Asteroid Research and
Near Earth Asteroid Tracking projects has meant that
most comets are now discovered by automated systems, long before it's possible for amateurs to see them.
Societies
There are a large number of amateur
astronomical societies around the world that serve as a meeting point for those interested in amateur astronomy, whether they be people who are actively interested in observing or "armchair astronomers" who may be simply interested in the topic. Societies range widely in their goals, depending on a variety of factors such as geographic spread, local circumstances, size, and membership. For instance, a local society in the middle of a large city may have regular meetings with speakers, focusing less on observing the night sky if the membership is less able to observe due to factors such as
light pollution.
It is common for local societies to hold regular meetings, which may include activities such as
star parties or presentations. Societies are also a meeting point for people with particular interests, such as
amateur telescope making.
Famous amateur astronomers
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