upon observing, how can you differentiate it from others?
It is typically the seventh-brightest star in the celestial sphere, it is visible on winter evenings in the Northern Hemisphere and on summer evenings in the Southern Hemisphere. In the Southern Hemisphere, it is the first bright star of Orion visible as the constellation rises.
Rigel
Rigel is an intrinsic variable star with an apparent magnitude ranging from 0.05 to 0.18. It is typically the seventh-brightest star in the celestial sphere, excluding the Sun, although occasionally fainter than Betelgeuse. It is fainter than Capella, which may also vary slightly in brightness. Rigel appears slightly blue-white and has a B-V color index of −0.06. It contrasts strongly with reddish Betelgeuse.

Culminating every year at midnight on 12 December, and at 9 pm on 24 January, Rigel is visible on winter evenings in the Northern Hemisphere and on summer evenings in the Southern Hemisphere. In the Southern Hemisphere, Rigel is the first bright star of Orion visible as the constellation rises. 
what is rigel? It s a blue supergiant star in the constellation of Orion. where did the word originate from? Latin.
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Rigel [SEP] Observation
Rigel is an intrinsic variable star with an apparent magnitude ranging from 0.05 to 0.18. It is typically the seventh-brightest star in the celestial sphere, excluding the Sun, although occasionally fainter than Betelgeuse. It is fainter than Capella, which may also vary slightly in brightness. Rigel appears slightly blue-white and has a B-V color index of −0.06. It contrasts strongly with reddish Betelgeuse. Culminating every year at midnight on 12 December, and at 9 pm on 24 January, Rigel is visible on winter evenings in the Northern Hemisphere and on summer evenings in the Southern Hemisphere. In the Southern Hemisphere, Rigel is the first bright star of Orion visible as the constellation rises.