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08/19/2019 – Ephemeris – The dimmest looking star of the Summer Triangle is by far the brightest

August 19, 2019 Comments off

Ephemeris for Monday, August 19th. Today the Sun will be up for 13 hours and 52 minutes, setting at 8:42, and it will rise tomorrow at 6:50. The Moon, half way from full to last quarter, will rise at 10:53 this evening.

This evening when it gets dark the bright star Deneb in Cygnus the swan will be very high in the east. Deneb is the dimmest star of the summer triangle. Of the other stars of the triangle, Vega is higher nearly overhead, while Altair is lower in the southeast. While Deneb’s apparent magnitude, or brightness as seen from Earth, makes it the dimmest of the three bright stars, Deneb’s vast distance of possibly 2,600 light years* makes it over 90 times the distance of Vega. If brought as close as Vega, Deneb would be as bright at least as the quarter moon. It is possibly as bright as 196 thousand suns; and a huge star, possibly as large in diameter as the orbit of the Earth. For all this it is only 20 to 25 times the mass of the Sun.

The times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

Great Rift in the Summer Triangle

The Great Rift finder animation as seen in the Summer Triangle, also showing the constellations of Cygnus the swan and the the northern part of Aquila the Eagle. This image a stack of 5 30 second exposures taken the morning of the Perseid meteor shower last year in a vain attempt to capture some meteors.