Archive for June 27, 2017

06/27/2017 – Ephemeris – Arcturus as a look at the Sun’s future

June 27, 2017 1 comment

Ephemeris for Tuesday, June 27th. Today the Sun will be up for 15 hours and 32 minutes, setting at 9:31, and it will rise tomorrow at 5:59. The Moon, 3 days before first quarter, will set at 12:18 tomorrow morning.

With the Moon brightening the night sky, let’s take a look at the star Arcturus, which with its pointer, the curve of the Big Dipper’s handle is slipping into the high western sky. Arcturus is the 4th brightest night time star, though some think the star Vega, high in the east is brighter. They are different colors because Arcturus is orange, while Vega is whiter than the Sun. Arcturus is a preview of what the Sun will become in four or five billion years from now. It is only 10% more massive than the Sun and is that much older than the Sun, so it is turning into its red giant stage, after running out of hydrogen to turn into helium in its core to produce energy. The helium is now compressing and heating to begin its reaction.

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


Arcturus finder chart

Arcturus finder chart with the Big Dipper and Vega as guide posts. Created using Stellarium.

Here’s one of my prior posts about Arcturus, about its great space velocity: