Download PISGAH Text by Dr. Bob Hayward ASTRONOMICAL Astronomer

PISGAH
ASTRONOMICAL
RESEARCH
INSTITUTE
Text by Dr. Bob Hayward
Astronomer/Educator
Graphics from TheSky
Software Bisque
Mountain Skies
June 6, 2016
THE HERDSMAN DRIVES THE GREAT BEAR AROUND THE SKY
The stars: An early evening in June is sometimes referred to as “The Arcturus Hour.” One can
find this brilliant ginger-colored star by using the handle of the Big Dipper. Following the arc of the
handle we come to Arcturus (and extending the arc farther, we encounter the bright white star Spica in
Virgo). Arcturus is the brightest star in the constellation of Boötes the herdsman and marks one of the
knees of this giant in the sky. At this time of year in the early evening Boötes appears to be lying on his
back as he rises in the east. To the north of Arcturus are two stars that mark the waist of the herdsman
and above these a triangle of stars
marks his shoulders and head. To the
south of Arcturus is a fainter star that
marks one of Boötes’ legs.
many
constellations
As with
Boötes
is
sometimes difficult to see from this
description.
We are probably more
familiar with this pattern visualized as a
kite. Arcturus is the bottom of the kite.
The two stars in the waist of Boötes
represent the middle of the kite and the
triangle at his head and shoulders
marks the top of the kite. The star in
the herdsman’s leg appears as a short
tail on the kite.
Boötes is often referred to as the bear driver since he follows the great bear (or Big Dipper)
around the sky as the earth rotates. In ancient times he had the important job of keeping the bear
moving since, if she ever stopped pulling the sky around, we would have eternal night or day. There
are several faint stars between Boötes and the handle of the Big Dipper that mark the constellation of
Canes Venatici, the hunting dogs. They constantly nip at the heels of the great bear.
The planets:
Three in the evening, one in the morning and one hiding behind the sun. This
describes the timing of the five visible or “classical” planets in early June. The giant Jupiter leads the
way and is high in the south at sunset. Lying just under the hind legs of the celestial king of the beasts,
Leo the lion, Jupiter, the king of the planets, is the brightest object in the sky. It will lose that distinction
this week, however, as a waxing crescent makes its appearance. By Friday night the moon will be
centered below Leo just to the west of Jupiter and, by the next night, it will have moved to the eastern
side of the giant planet. If you watch these two over this period, you will get a good feeling for just how
much the moon moves each night. It takes it 27⅓ days to make a complete circle through the zodiac;
we call this the sidereal month.
To the east of Jupiter as the sky darkens is the red planet Mars now hanging around in the
middle of Libra the scales. Mars was at its closest point to the earth on May 30 and, thus, is very bright
right now, almost as bright as Jupiter the second brightest planet in the sky. Look for Mars well up in
the southeast as the sky darkens. On the evening of June 16 the moon will lie just above Mars.
Two nights later the moon will have moved on eastward to lie near Saturn. The ringed planet is
not as bright as either Jupiter or Mars but should be visible even close to an almost full moon. Saturn is
putting on a show now. Its beautiful rings are tilted towards us just over 26 “open” and it is a beautiful
sight through a telescope. The light reflected off the rings adds to that from the planet itself to make
Saturn unusually bright. Also, it was at opposition, its closest point to the earth this past Friday.
The elusive planet Mercury has shifted from the evening to the morning skies as it passed
directly in front of the sun back on May 9. It is visible to the dedicated observer very low in the morning
twilight. However, it is not an easy task to find it and, thus, is elusive.
Venus the brightest of the planets is in superior conjunction behind the sun today. It is doing the
opposite of what Mercury did on May 9. Venus is switching from the morning skies to the evening
skies. It will be several more weeks before we can spot it in the evening twilight but then it will be our
“Evening Star” for the rest of the year and beyond.
Celestial Calendar:
June 4, 11 p.m. EDT – New Moon
June 12, 4:10 a.m. EDT – First Quarter Moon
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PARI is a public not-for-profit public foundation established in 1998. Located in the Pisgah Forest
southwest of Asheville, NC, PARI offers educational programs at all levels, from K-12 through post-graduate
research. For more information about PARI and its programs, visit www.pari.edu. Follow PARI on Twitter at
http://twitter.com/Astronomy_PARI. “Like” PARI on Facebook at
www.facebook.com/Pisgah.Astronomical.Research.Institute.
For further information or questions about this Mountain Skies column, contact Dr. Bob Hayward at
[email protected]. Graphic produced by the author with TheSky Astronomical Software, Software Bisque.