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Equation 3 · Part 2 · Comparing the Main Approaches to Planetary Science and Exploration

Symbol λ

θ≈1.22 λD.\theta \approx 1.22\,\frac{\lambda}{D}.
λ\lambda

What this part means

the wavelength.

Its job in the formula

λ occurs above the fraction bar. The numerator is divided by the entire denominator below it.

Where the article explains it

For a telescope with aperture diameter D observing light of wavelength λ\lambda , the smallest angular separation it can resolve is approximately θ≈1.22 λD\theta \approx 1.22\,\frac{\lambda}{D}.

The passage around this formula

…defining strength and its defining limitation is spatial resolution, which is fixed by the physics of diffraction rather than by mission budget. For a telescope with aperture diameter D observing light of wavelength λ\lambda , the smallest angular separation it can resolve is approximately θ≈1.22 λD\theta \approx 1.22\,\frac{\lambda}{D}. This relation is why an exoplanet studied by transmission spectroscopy is a single point of light with no visible surface at all — the target subtends an angle far smaller than θ\theta for any existing…

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Learn the underlying idea

A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.

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Sources cited in the article section

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