Observations, Models, and Evidence

Objective: Explain astronomy and observation, distinguish their meanings, and apply them to a described case.

Astronomy: Astronomy studies celestial objects and phenomena using observations and physical explanations. Observation: An observation records a measured or perceived feature under stated conditions. Astronomical observations are interpreted through physical models and measurement procedures. A coordinate locates an object relative to a reference system; it does not by itself give a physical distance. Units must be distinguished from the quantities they measure. Seeing distant light means seeing an earlier emission event. Explain which observation supports a claim and which additional measurement would reduce its uncertainty. Application: A researcher compares starlight with a physical model. This most directly illustrates astronomy. A detector records brightness at several times. This most directly illustrates observation.

Objective: Explain inference and model, distinguish their meanings, and apply them to a described case.

Inference: An inference interprets observations using reasoning and assumptions. Model: A model represents selected mechanisms and makes testable predictions. Astronomical observations are interpreted through physical models and measurement procedures. A coordinate locates an object relative to a reference system; it does not by itself give a physical distance. Units must be distinguished from the quantities they measure. Seeing distant light means seeing an earlier emission event. Explain which observation supports a claim and which additional measurement would reduce its uncertainty. Application: A spectrum supports an estimate of a star's composition. This most directly illustrates inference. An orbital model predicts a future position. This most directly illustrates model.

Objective: Explain uncertainty and independent evidence, distinguish their meanings, and apply them to a described case.

Uncertainty: Uncertainty characterizes limits in measurements or interpretations. Independent evidence: Independent evidence tests an interpretation using observations with different relevant limitations. Astronomical observations are interpreted through physical models and measurement procedures. A coordinate locates an object relative to a reference system; it does not by itself give a physical distance. Units must be distinguished from the quantities they measure. Seeing distant light means seeing an earlier emission event. Explain which observation supports a claim and which additional measurement would reduce its uncertainty. Application: A distance estimate is reported with an error range. This most directly illustrates uncertainty. A conclusion uses both orbital motion and spectra. This most directly illustrates independent evidence.