{"knowledge_schema": {"broad_category": "Astronomy \u2192 Cosmology \u2192 Redshift", "refinement": "This problem involves calculating the redshift of a distant galaxy based on the observed wavelength of a spectral line compared to its known rest wavelength.", "specific_scope": "The focus is on the Lyman-alpha line, which is a specific spectral line of hydrogen, and how its observed shift indicates the galaxy's velocity relative to Earth.", "goal": "Calculate the redshift (z) using the formula z = (observed wavelength - rest wavelength) / rest wavelength."}, "summary": "This problem is centered around the concept of redshift in astronomy, which measures how much the wavelength of light from distant objects has been stretched due to the expansion of the universe. By comparing the observed wavelength of 850 nm to the known rest wavelength of the Lyman-alpha line at 121.5 nm, we can calculate the redshift using the formula z = (observed - rest) / rest. The goal is to determine the redshift value, which in this case is found to be z = 6."}