Getting the GREEEN LIGHT

A small handful of stars appear to glow emerald in the night sky. Astronomer Phyllis Lang reveals how to spot them

For many years I’ve observed all kinds of deep-sky objects. I have been most interested in planetary nebulae, partly because they’re most likely to show colour. Within the last few years I’ve also become interested in the colours of stars, particularly colour-contrasting double stars. A long-time observing friend of mine brought up the idea of observing green stars, and a social observing project began. Stars seem to appear in almost every colour of the rainbow, and both eye physiology and the spectrum play a part in that. The novice observer may detect no colour in stars but, in fact, any star has an apparent colour that is detectable with photometry. The star’s light can be filtered so that separate colour components (wavelengths) can have their brightness measured. The brightness of…

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The Astronomer's Yearbook 2019 (Digital) - 1 Issue, Astronomer's Yearbook 2020

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