Observing Skills · 9 of 12
Stars That Keep Time
Which stars change brightness on a timetable?
Algol dims as its companion passes in front; δ Cephei pulses and reddens — and the Cepheids measured the distance to the Andromeda Galaxy.
You’ll be able to catch Algol in eclipse and follow a Cepheid through its cycle.
Before this: Understanding Star Brightness (10 min)
Where and which night
Working out when this is best placed from where you are…
Where
Kept for this guide only, until you change it here — your map settings, and every other guide, stay as they are.
Print, play outside or present
Scan with a phone's camera, or open
Sources
- General Catalogue of Variable Stars (Samus et al., GCVS v5.1), VizieR B/gcvs — ranges and classes
- Kreiner, Acta Astron. 54, 207 (2004) — up-to-date elements of eclipsing binaries, Algol’s clock
- Berdnikov, UBVRI photometry of Cepheids (1997), VizieR II/217 — δ Cephei’s colour through its cycle
- Leavitt & Pickering, Harvard College Observatory Circular 173 (1912) — periods of 25 variables in the Small Magellanic Cloud
- Hubble, "A spiral nebula as a stellar system, Messier 31", ApJ 69, 103 (1929)
- Goodricke, Phil. Trans. 73, 474 (1783) — Algol’s period, and the suggestion of an eclipsing body
With a keyboard, focus the sky, aim it with the up and down arrow keys, and press Enter to drop the pin at the centre of the view; or press Show me.