Theories play a big role in science! I recently presented a short introduction for beginners about science theories (see “Towards Understanding Theoretical Research in Science!” ). Here, we will look at some current research developments in Astronomy that illustrate examples of theories within space research.
A brief background for beginners on the science of Astronomy!
Knowledge in ancient times about our planet, Earth, our Moon, our Sun, and the stars came from direct observations with the naked eyes. The early development of telescopes, photography, and other ways to record positions of celestial objects permitted measurements to be made; that was the real start of astronomy as part of physical science.
Astronomy today has the tools and technology to examine everything from the other planets circling our Sun, to distant galaxies and energy emissions in outer space. Modern research in astronomy has been expanded by the development of space science with its explorations using robotic labs sent on distant travels, space telescopes and new large terrestrial telescopes, and, numerous advanced spectroscopes. These tools and methods gather quantitative data that go far beyond what could be done by researchers only a few decades ago. The new availability of direct measurements means that theories in astronomy now can be tested against real data.
Do exoplanets exist!
Humans have long wondered if we are alone, or if there are other planets with life somewhere out in the universe. A theory that exoplanets (i.e., planets circling other stars) do exist is mirrored by a theory that there are no others! The validity of any theory must be tested by evidence from research results. Due to their limited size and great distance away from Earth, exoplanets cannot yet be directly imaged by any terrestrial telescopes; space telescopes should be able to do that, if exoplanets actually exist. Instead of using light waves to form images, telescopes and radiotelescopes now can detect other wavelengths and types of radiation, and record spectra rather than images; much development in this research methodology has resulted in good confidence for interpretating spectroscopic data, although confirmation from adjunctive results always also is sought. Recent discoveries of hundreds of planets orbiting many other stars [e.g., 1] establishes validity of the theory that exoplanets do exist.
Proxima b is discovered!
One exoplanet, Proxima b, has just been reported by an international team of scientists, after analyzing research data back to 2000 ! It is slightly larger than Earth, and encircles our neighboring star, Proxima Centauri, with a periodicity of 11.2 days; its equilibrium temperature permits liquid water to be present. There is much excitement in astronomy over this new research finding, because its relative closeness to Earth means that it will be a prime target for future fly-by missions. A new article for general readers about the discovery of this exoplanet, written for CNN by Ashley Strickland , now is available (see: “Proxima b: Closest potentially habitable planet to our solar system found” ).
Does water exist on any exoplanet?
Liquid water is a key component of all forms of life on Earth. Any theory that life exists on exoplanets generally requires the presence of water there; this links one theory to another theory! Space scientists are already defining the width of a zone around some stars as being habitable if its temperature range includes that required for liquid water to be present; however, such an estimation does not establish that water actually is present. Much more direct research data is needed to be able to resolve this important question.
Does life exist on any exoplanets?
The enormous distance of exoplanets from Earth makes any theory that life is present there extremely difficult to test. The distant locations make it impractical to send scientists or robots out to any exoplanet via a spaceship. Several innovative ideas for how to obtain direct images of exoplanets now are being developed and activated (e.g., see “Can Research Travel Out to the Stars? Yuri Milner Says “Yes, Let’s Go!” ). Advanced spectroscopy perhaps is the only currently available means to detect life forms on exoplanets, since direct imaging is not yet possible.
How to interpret images from exoplanets?
Direct imaging of exoplanets is eagerly awaited! All images in science must be interpreted, but the interpretation of future direct images from exoplanets is guaranteed to be a major controversy since images showing either creatures resembling those we all know on Earth, or something wildly different, will provoke vigorous doubts by other scientists and the public! Life might exist that utilizes other means for energy mobilization, and does not need either water or oxygen; thus, exotic life forms imaged on exoplanets might not be recognizable as such! Objective interpretation of those images might be nearly impossible!
Nothing is written in stone, and everything can be questioned by scientists! Theories are particularly useful in science as targets for new research experiments. All theories must be evaluated on the basis of their ability to explain direct observations and measurements. Theories can be proven or disproven by evidence from research results; valid theories have a predictive ability. Even proven theories can be modified as more research data becomes available. Speculative ideas and imaginative proposals differ from science theories because they are judged largely on the basis of popularity and subjective promise, rather than by direct evidence.
Theories in science always are controversial and hard to prove. In space science, new research results now permit the validity of some theories to be tested directly. These indeed are very exciting times for space scientists!
 Anglada-Escudé, G., et al., August 25, 2016. A terrestrial planet candidate in a temperate orbit around Proxima Centauri. Nature 536:437-440.
 Strickland, A., for CNN, August 24, 2016. Proxima b: Closest potentially habitable planet to our solar system found. CNN – Health.
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