EYES TO THE SKY
May 28 – June 9, 2019
The Spring Triangle – an asterism
While writing my recent column about bright stars in the south at nightfall, I was reminded of patterns those stars shape in addition to the position each has in an official constellation. Arcturus is the brightest star in the constellation Bootes the Herdsman and Spica is brightest in Virgo the Virgin. Denebola marks the tail of Leo the Lion and Regulus the Lion’s heart. Draw imaginary lines to connect Arcturus to Spica and Denebola and we have a Spring Triangle, an asterism. Replace Denebola with Regulus for a larger Spring Triangle.
Asterisms are easily distinguishable patterns often composed of stars from more than one constellation. In the case of the Big Dipper – overhead to the south — the asterism is an outstanding part of one official constellation, Ursa major, the Great Bear.
While venturing out at nightfall to enjoy the asterisms, be sure to appreciate the Crow careening in the south and the full figure of the Lion striding high in the southwest.
Stargazer’s Calendar: Least moonlight makes for best two week period for stargazing: last quarter moon was on the 26th; waning crescent today rises in the east-southeast at 2:43.m, introducing a week of early morning crescents in the east, also visible in the daytime sky. New moon next Monday, June 3, introduces week of evening crescents in the west. First quarter moon near Denebola on the 9th.
Judy Isacoff naturesturn.org
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