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PISGAH
ASTRONOMICAL
RESEARCH
INSTITUTE
Text by Dr. Bob Hayward
Astronomer/Educator
Graphics by TheSky
Software Bisque
Mountain Skies
July 18, 2016
ALL FIVE VISIBLE PLANETS APPEAR AFTER SUNSET
The planets: They’re back! All five of the visible or naked-eye planets are now in the evening
skies although Venus and Mercury are still very low in the evening twilight and, thus, a bit difficult to spot.
The other three, from east to west, are Saturn, Mars and Jupiter and each of these is easy to spot as the
sky darkens. Jupiter, which has been our “Evening Star” since about mid-March has now moved farther
to the west and shines brightly about a third of the way up in the southwest as the sky darkens. It is
quickly sinking into the west and will be lost to us by early September.
The red planet Mars is well up in the south these evenings. It is quickly dimming as the earth
moves away from it but still outshines any of the stars in the sky. The observer with a good telescope
can still make out some of the markings on the surface. (With the exception of Mercury, Mars is the only
planet whose surface marking can be observed from the earth and even they are sometimes obscured
by the monster dusk storms that have been observed on this fascinating planet.)
The third of the trio of bright planets is the beautiful ringed planet Saturn. If you have not viewed
Saturn through a telescope recently, make an effort to do so. Its rings are fully “open” as we say meaning
they are tilted the maximum towards the earth and present a beautiful picture through a telescope. They
also contribute to Saturn’s brightness making this planet, while not as bright as Jupiter, Venus or Mars,
easily spotted above Antares, the heart of the scorpion.
So, there you have it…three bright planets easily visible after sunset all month long plus two
making appearances very low in the evening twilight late in the month. All five of these will remain visible
throughout the month of August.
The stars: Now that summer is upon us, it’s not too early to look high in the east in the early
evening for the so-called “Summer Triangle.” This pattern of three bright stars is not one of the classical
constellations
but
rather
what
astronomers refer to as an asterism.
In fact, the corners of the triangle lie
in
different
constellations
each
associated with a bird in classical sky
lore. Highest and brightest is Vega in
the constellation of Lyra the lyre or
harp. This is the musical instrument
with which Orpheus charmed so
many of the young ladies in his time.
After the untimely demise of his wife
Eurydice on their wedding day,
Orpheus
rescued
her
from
the
underworld but left his lyre behind.
Jupiter sent the vulture to retrieve it.
Thus, on star maps we often see the lyre carried by a vulture.
To the northeast of Lyra is the bright star Deneb that represents the tail of the beautiful swan
Cygnus. Tracing a line of stars from Deneb towards the south, we note the body and long neck of the
swan terminating in the star Albireo that marks the eye of the swan. (Look at Albireo with a small
telescope and you will note a colorful double star.) To the sides of the swan we can trace out his wings.
Cygnus was the close friend of Phaeton who was the son of Helios the god of the sun. When Phaeton
lost control of his father’s horses and was knocked from the sky by a thunderbolt from Jupiter, Cygnus
dove into the river Eridanus to recover his friend’s body. For this kind deed he was placed in the sky to
be a reminder to all of us that it is good to help a friend. For some people the swan can be found more
easily if imagined as “The Northern Cross” with the top of the cross in Deneb and the bottom of the upright
marked by Albireo. The wings of the swan then become the cross arm of the cross.
Finally, to the south is the bright star Altair in Aquila the eagle. Jupiter sent his royal bird to earth
to bring the boy Ganymede to Mount Olympus to become the cup bearer for the gods.
Celestial Calendar:
July 19, 6:57 p.m. EDT – Full Moon
July 21 – Sun appears to move from Gemini the twins into Cancer the crab
July 26, 7:00 p.m. EDT – Last Quarter Moon
August 2, 4:45 p.m. EDT – New Moon
August 5-6, Midnight EDT – Jupiter 0.2º north of the moon
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PARI is a public not-for-profit public organization established in 1998. Located in the Pisgah National 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].
Graphics produced with The Sky Astronomical Software, Software Bisque.