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04/06/2018 – Ephemeris – Marking the passage of 13 hours of daylight

April 6, 2018 Comments off

Ephemeris for Friday, April 6th. The Sun will rise at 7:14. It’ll be up for 13 hours and 2 minutes, setting at 8:16. The Moon, 2 days before last quarter, will rise at 2:33 tomorrow morning.

Tomorrow morning early, the crescent Moon will pass Saturn and Mars. These planets will be below the Moon in the dark early morning hours. The dark night hours will be increasingly more inaccessible as summer approaches. Today we’ve broached 13 hours of daylight. By the summer solstice on June 21st the Sun will be out just a bit over 15 and a half hours. Meaning that the Sun will be down for only eight and a half hours, with only three and a half hours of really dark sky, Moon permitting, between the end of evening astronomical twilight and the beginning of morning astronomical twilight. Twilight is really long around the summer solstice because the Sun sets at a shallow angle.

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

Addendum

Definitions

End or start of Civil Twilight:  Sun is 6° below the horizon

Brighter planets become visible

End or start of Nautical Twilight:  Sun is 12° below the horizon

Brighter deep sky objects can be found for public star parties

End or start of astronomical twilight:  Sun is 18° below the horizon

On moonless nights, the twilight glow is gone and the sky is dark

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