Image Caption: Artistic concept of a planetary system. Credit: Wikipedia/NASA/JPL-Caltech
The term Astronomy encompasses a broad range of topics, including the study of stars, galaxies, and planets. In order to focus on the different areas of study, many subfields of astronomy emerge. One such area is the study of planets known, appropriately, as Planetary Astronomy.
Observational Planetary Astronomy
Even within the field of Planetary Astronomy, there are several divisions to consider. The first, and perhaps the most obvious, is the observational study of different worlds.
While the immediate assumption is that optical wavelengths would be the primary radiation studied, observational astronomers use everything from radio waves to infrared light to infer information about planets.
From these studies, insights into a planet’s atmosphere, composition, magnetic field, and other such properties can be deduced. The ultimate goal of Observational Planetary Astronomy is to discover new characteristics, and better understand the complexities of planets beyond Earth.
Theoretical Planetary Astronomy
While observational data certainly plays an important role in all aspects of Planetary Astronomy, a lot of effort is put into developing theoretical models about how planets form and evolve. Data from Observational studies are used to constrain these models, and provide grounds for developing new theories about planetary objects.
In the last couple decades the role of theoretical Planetary Astronomy has changed as planets outside of our Solar System have been discovered with increasing frequency. And what has been found is that other solar systems have formed very differently than our own, challenging what we thought we knew about how planetary systems arise and evolve.
Study of the Solar System
Naturally, the place to begin the study of planets is in our own neighborhood, with the objects orbiting the Sun. Crossing the heavens in such close proximity, our nearest neighbors provide an opportunity to study – often up close – the atmospheres, surfaces, magnetic fields, rings, and moons of planets.
This provides a rare opportunity to actually interact with celestial bodies; often they are so distant that we must rely on long-traveled beams of light to give us clues about their presence.
The Search for Extrasolar Planets
The earliest Planetary Astronomers studied exclusively our Solar System, as planets beyond our corner of the galactic neighborhood were simply too far away to even identify, much less identify anything scientifically interesting.
But with increased instrument sensitivity and resolution, we are now able to infer the existence of planets around other stars, and in some cases even optically resolve them.
Researchers in this area of Planetary Astronomy use multi-wavelength data, coupled with various observational techniques, to discover and characterize new solar systems. Information about planetary mass and orbital distances are the primary properties studied at this juncture.
As technology continues to improve, however, researchers will eventually be able to study planetary atmospheres and even search for the presence of compounds, such as water, on their surfaces.
Also, new telescopes are being developed that will allow us to increase our sensitivity to smaller worlds – to date most, though not all, of our discoveries are of planets larger than Earth as they are easier to detect.
So while Planetary Astronomy is probably one of the oldest divisions of Astronomy, modern technology has rapidly changed the landscape of the field. In many ways, Planetary Astronomy has emerged as one of the most exciting areas of science as researchers continue their quest to find another world similar to Earth.