Pierre de Fermat, one of the preeminent mathematicians of the 17th century, was a lawyer by trade.  Michael Faraday was a bookbinder with only a grade school education and discovered the relation between electricity and magnetism.  But the current cutting edge of physics and math require such specialized knowledge of abstract concepts that generally only professionals can make new discoveries.  Astronomy is possibly the only science left where amateurs can still make significant contributions.  This is largely due to the fact that the universe is just too big for the small number of professional astronomers to handle all the data by themselves.  Also, much of the science does not require multimillion-dollar equipment.  Some of it does, of course, but below you will find ideas for real science that can be done with amateur equipment from your own backyard.

Variable Stars

CCDs make it easy to study the changes in brightness of stars.  Variability in stars indicates the occurrence all types of different phenomena, so studies can be done in many areas just by watching starlight change.  Variable star types include cataclysmic variables, long period variables, eclipsing binaries, novae and supernovae.  Gamma ray bursts and transiting exoplanets also create variability in stellar brightness, and these subjects are given their own sections below.

Studying variable stars with a CCD camera is fairly straightforward.  Basically it involves taking images of a given star and comparing that star to other stars of known brightness.  Changes can be plotted to determine the characteristics of the variation.  Multiple images are taken at any given time to eliminate errors due to noise, seeing conditions, etc.  Also, accurate calibration images such as dark frames, flat fields, and bias frame must be taken to eliminate any other possible errors.  This allows detection of very small changes in brightness.

The required telescope for variable star observing need not be particularly large, especially for brighter stars.  For those who wish to image much fainter targets, more aperture is better.  In general, an 8" scope is sufficient for most work.  A non-antiblooming CCD camera is also recommended.  While antiblooming is ideal for taking pretty pictures (because it eliminates ugly blooming spikes from bright stars), it also leads to the CCD having a non-linear response.  This means the relationship between stars of different brightness will not be linear, meaning accurate measurements with comparison stars mill not be possible in many cases.  For more detail on variable star observing programs with a CCD camera, see the AAVSO website.

Gamma Ray Bursts

Gamma ray bursts (GRBs) are high-energy events in which tremendous amounts of the most energetic type of radiation is given off in just a few seconds.  Most GRBs are associated with certain types of supernova explosions.  A GRB may last only a fraction of a seconds, though some persist for several minutes.  The gamma ray photons are detected by orbiting satellites.  The sources and characteristics of GRBs are still somewhat of a mystery, so research in this area is at the forefront of astronomical science.  Where amateur astronomers come in is that scientists need to know what sort of optical counterparts there are to these high-energy bursts.  A network of coordinated telescopes has been established to try to find these optical counterparts.  When a satellite detects a gamma ray burst, a notification is sent out and any available telescopes are rapidly pointed to the location of the burst.  These observations can contribute to our understanding of the universe.  More information is at the AAVSO website.

Extrasolar Planets

This is possible the most exciting area of research right now.  Astronomers have finally begun to discover planets beyond our own solar system, and the goal now is to understand how these other systems form, how they shed light on the formation of our own planetary system, and whether there exist other Earthlike planets.  Amateurs can provide data on exoplanets by observing variations in stellar brightness as a planet transits in front of its star.  These changes in brightness are very small and require precise observations to achieve the 1% accuracy required, but they can be detected using modest equipment.

An even more interesting possibility is that of amateurs detecting extrasolar planets by the shift in the spectrum of a host star.  As of July, 2007, almost 250 planets were known outside the solar system.  Only 22 of these were discovered by observing the planet transiting its star, so the majority have been found by radial velocity measurements as the planet's gravity tugs slightly on its star.  This shift in the stellar spectrum is tiny, but not entirely outside the range of amateur equipment.  At least one amateur group had detected a known exoplanet using this method.  See www.exoplanet.eu and www.spectrashift.com for more details.

Searching for New Objects

An obvious part of astronomy where amateurs have always made contributions is in discovering new objects.  Comets and asteroids are frequently discovered by amateurs.  While automated surveys by professionals are sweeping the sky and picking up many of the discoveries that amateurs might have made, new technology allows amateurs to compete with and compliment these professional observations.  This subject is detailed enough to warrant its own page, so check out The Search Begins for more details.

Asteroid Studies

In addition to discovering new asteroids, there is much research to be done in studying known asteroids.  A knowledge of the orbital and compositional characteristics of near-Earth asteroids is important in studying and possibly defending ourselves from these threatening objects.  Such studies can be done astrometrically, photometrically, or spectroscopically.  Astrometric measurements are used to determine the position of an object, and these measurements can be used to refine the orbital properties of an asteroids.  This is especially important for fast-moving near-Earth asteroids.  Photometric analysis can be used to determine the size and rotation of an asteroid, leading to knowledge about its composition.  Spectroscopic studies will give more detail on what the asteroid is made of -- an important thing to know if you want to move it so it doesn't hit Earth!

Planetary Observations

The planets are quite dynamic and study of their changing weather patterns can easily be done by amateur astronomers.  Jupiter is the prime example.  Storms are always forming, changing, and dissipating on this giant planet.  The bands fade and intensify.  Weather systems interact and modify each other.  All these events can be tracked by amateurs with relatively inexpensive equipment.  Mars is also a good subject for study when it is nearest to Earth.  The polar ice caps, dust storms, and clouds can all be observed on Mars.  These events tell astronomers more about global climate patterns on the red planet.  Planetary observation can be done with a telescope of moderate aperture and a simple webcam for capturing data.  The most critical factor is weather, since seeing conditions determine the amount of detail that can be resolved in a planetary image.  Observers with clear skies and calm air can easily begin planetary observing programs.

Unknown Deep-Sky Objects

Recently amateur astronomers have been discovering not just comets and asteroids, but also objects beyond our own solar system.  Deep images have uncovered faint nebulosity unseen in earlier CCD images.  This integrated flux nebulosity can now be captured and mapped using modest equipment.  See Steve Mandel's website for details on this observing program.  Un-cataloged planetary nebulae are being discovered by amateurs as well.  Narrowband-filtered images are being used to detect these objects, which stand out clearly in deep exposures through such filters, whereas they might be seen simply as stellar objects in earlier surveys.  See Richard Crisp's website for more details.

More

The new technology available to amateur astronomers is letting them push the boundaries of backyard astrophysics.  The future will hold not only new discoveries in existing areas of astronomy but will likely uncover aspects of the universe we do not yet even know.

CCD Imaging Projects