Question 1

What is stellar magnitude?

Accepted Answer

Astronomical brightness scale where lower = brighter. Each magnitude step is 2.512× brightness difference. Sun: -27. Full moon: -13. Brightest star (Sirius): -1.46. Naked eye limit: +6.

Question 2

How do apparent and absolute magnitude differ?

Accepted Answer

Apparent magnitude: how bright from Earth. Absolute magnitude: how bright at 10 parsecs (32.6 light-years). The Sun is apparent -27 but absolute +4.83.

Question 3

What's the difference between lumens and lux?

Accepted Answer

Lumens measure total light output from a source. Lux measures light arriving at a surface. Same lumens in a smaller area = higher lux.

Question 4

How do I convert old wattage to lumens?

Accepted Answer

Roughly: 40W incandescent ≈ 450 lumens, 60W ≈ 800 lumens, 100W ≈ 1600 lumens. LED equivalents use 80-90% less power for same lumens.

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