Jeffers Foundation



October, 2017

October 15 at 8 pm CDT
October 15 at 8 pm CDT
One of the most famous stars in the fall sky is Algol. This star's name means "the ghoul," referring to variations in its brightness noticed by ancient skywatchers. Most of time, Algol appears as a second magnitude star. Every 2.9 days the star dims by a little more than one magnitude, becoming a third magnitude star for about three hours. This change is easy to see. Locate Algol midway between the W-shaped constellation Cassiopeia and the Seven Sisters star cluster. Check Algol's brightness at 8 pm and then again at 10:45 pm to observe Algol's famous "wink."

Morning Sky

Venus has been getting lower every morning since early August. Next month, it will disappear into the Sun's glare. To see Venus before it departs, look approximately eight degrees above the eastern horizon one hour before sunrise. Mars climbs higher in the pre-dawn sky, passing Venus on October 5. This conjunction is a very close one, the planets will be just one-fourth of a degree apart - half the apparent width of the Moon! On the morning of October 17, the Moon will pass Venus and Mars, a fitting finale to the events involving Venus and Mars this month.

Evening Sky

Mercury enters the evening sky on October 8, but remains too close to the Sun to see. Jupiter leaves the evening sky on October 26. Like Mercury, it is also too close to the Sun to see. So, Saturn is the only planet visible after sunset. To see it, look about 15 degrees above the southwestern horizon 60 minutes after sunset. The Moon passes Saturn on October 24.

Sun Declination


5th, Full Moon (Harvest Moon) - 1:40 pm

7th, Mars at aphelion; Mars-Sun distance = 154,872,555 miles - 5:07 pm

9th, Moon perigee; 227,953 miles - 12:51 am

12th, Last Quarter Moon - 7:25 am

15th, Regulus 0.2 degrees north of Moon (Occultation 4:45-5:18 am) - 5:03 am

15th, Variable star, Algol, at min brightness (+3.4) - 10:46 pm

19th, New Moon Freezing (Ojibwe) - 2:12 pm

21st, Orionid Meteor Shower peak - 5:54 am

24th, Moon apogee; 251,757 miles - 9:26 pm

27th, First Quarter Moon - 5:22 pm

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