Friday, July 26, 2024

The Summer Triangle (all night)

After dusk in mid-July, the first stars to appear in the darkening eastern sky are Vega, Deneb, and Altair. Those three bright, white stars form the Summer Triangle asterism - an annual feature of the summer sky that remains visible until the end of December! The highest and most easterly of the trio is Vega, in Lyra. At magnitude 0.03, Vega is the brightest star in the summer sky, mainly due to its relative proximity. It's only 25 light-years away from the sun. Magnitude 0.75 Altair, in Aquila, occupies the lower right (southern) corner of the triangle. Altair is 17 light-years from the sun. By contrast, Deneb, which shines somewhat less brightly at magnitude 1.25, is a staggering 2,600 light- years away from us; but it shines so brightly because of its greater intrinsic luminosity. The Milky Way passes between Vega and Altair and through Deneb.


Double Shadows on Jupiter

On Saturday morning, July 27, observers located in the South Pacific and New Zealand can watch two shadows crossing the southern hemisphere of Jupiter at the same time for about 90 minutes. At 3:58 a.m. New Zealand Standard Time (or 15:58 UT), the shadow of Io will join the shadow of Europa, which began its
own crossing of the planet an hour earlier. Europa's shadow will leave Jupiter at 5:28 a.m. NZST (or 17:28 UT), leaving Io's shadow to continue on alone
until 6:08 a.m. NZST (18:08 UT).

(Data courtesy of Starry Night)
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* Origin: CJ's Place, Orange City FL > cjsplace.thruhere.net (21:2/156)