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Bob Moler's Ephemeris Blog

07/06/2020 – Ephemeris – The southernmost star of the Summer Triangle, Altair

6 Jul 2020, 04:01 UTC
07/06/2020 – Ephemeris – The southernmost star of the Summer Triangle, Altair
(200 words excerpt, click title or image to see full post)

This is Bob Moler with Ephemeris for Monday, July 6th. Today the Sun will be up for 15 hours and 25 minutes, setting at 9:30, and it will rise tomorrow at 6:05. The Moon, 1 day past full, will rise at 11:02 this evening.
The southernmost star of the Summer Triangle is Altair, high in the east-southeast. The other two stars of the triangle are Vega nearly overhead in the east, and Deneb high in the east-northeast. Altair is the closest of the three at a distance of 16.7 light years away. One light year is nearly 6 trillion miles. Altair is 10 times the brightness of the Sun. If seen at Altair’s distance, the Sun would only be as bright as one of the two stars that flank it. What is rather different about Altair is its rapid rotation. While it’s almost twice the sun’s diameter, it rotates once in about 9 hours, The CHARA Interferometer at Mt. Wilson has actually imaged its squashed disk in the infrared. Our Sun’s a slow poke, taking nearly a month to rotate once.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

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