Download Jupiter-Mars Encounter 17 October 2015

Astro Advisory
Notice of an upcoming
astronomical event.
PISGAH
ASTRONOMICAL
RESEARCH INSTITUTE
Contact: Bob Hayward, Astronomer/Educator
828-877-6348 or 828-862-5554 ([email protected])
John Avant 919-848-1153 ([email protected])
MARS PASSES JUPITER IN THE MORNING SKIES
Rosman, NC (September 30, 2015) – Astronomers at the Pisgah Astronomical Research
Institute have been watching the red planet Mars in the predawn skies since late July
when it emerged from the morning twilight after passing behind the sun on June 14. In
September Jupiter also emerged from its August 28 conjunction behind the sun and
joined both Mars and Venus in the morning twilight.
At the present time all three of these naked-eye planets are slowly moving eastward under
the tail of Leo the lion. Since Mars is closer to the sun than is Jupiter, the red planet
moves more swiftly and the gap between the two is closing. On the morning of October
17 that gap will be a mere 0.4 degree, less than the diameter of the moon. Jupiter, being
the second brightest planet in the sky is easily spotted. Mars, while definitely visible to
the naked eye, is much fainter and appears slightly red to the eye, thus its appellation as
the “red planet.” Following this pairing of the two planets, Mars will continue its journey
around the sun and will move farther below Jupiter.
But that’s not the whole show! Above and slightly to the right of Mars and Jupiter is the
brilliant Venus unmistakable as our current “Morning Star.” And below these three lies
the elusive planet Mercury. Venus and Jupiter are so bright that they are visible even to
the casual observer. Mars and Mercury are much fainter but can be found by noticing
Mars close to the left of Jupiter and Mercury somewhat lower in the twilight. Mercury is
well placed to spot on the 17th since, two days previously, it reached its greatest
elongation from the sun placing it a full 18 degrees away from our central star.
Realize the successful observer will have seen four of the five naked-eye planets now in
our morning skies. The fifth, Saturn, is currently low in the west at sunset. It passes
behind the sun in conjunction on November 30 and by the holidays will have joined
Venus, Jupiter and Mars in the morning twilight. By that time, however, Mercury will
have passed behind the sun in the other direction and will be in our evening skies.
About PARI
PARI is a public not-for-profit public foundation established in 1998. Located in the Pisgah National
Forest southwest of Asheville, NC, PARI offers STEM educational programs at all levels, from K-12
through post-graduate research. For more information about PARI and its programs, visit www.pari.edu.
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