Astronomy Club of Asheville October 2017 Sky Events · · 2017-10-01Astronomy Club of Asheville October 2017 Sky Events ... Leo & Virgo 10.8-3.9 Shining brightly low in east at

Astronomy Club of Asheville

October 2017 Sky Events

The Planets this Month – page 2

Close Conjunction of Venus and Mars – page 7

Crescent Moon with Antares and Saturn – page 8

Planet Highlights – page 9

Moon Phases – page 12

October 15th - the Moon Occults Regulus – page 13

Find the Zodiacal Light – page 15

October 21st - Orionid Meteor Shower Peaks – page 18

October 29th - Asteroid Pallas at Opposition – page 21

www.AstroAsheville.org

http://www.astroasheville.org/

Our evening sky offers just a single bright planet this month – but what a planet! Splendid Saturn graces our dusk skies in October, but you’ll need to catch the ringed planet early, no later than 2 to 3 hours after sunset, and before the planet descends too low to the southwestern horizon to be seen well.

Found in the constellation Ophiuchus, the Serpent Bearer, its ring system is now tilted at a maximum 27 degrees towards the Earth, providing excellent telescopic views of the planet’s northern hemisphere.

At the beginning of October, Jupiter might be glimpsed shortly after sunset, scarcely hugging the western horizon and nearly engulfed in twilight’s glow.

The gas giant’s last gasp will soon succumb to the Sun’s glare. Jupiter reaches solar conjunction on October 26th, when its orbit passes behind the Sun, re-emerging in our morning skies next month.


October 2017 Sky Events – the Planets

Also lost in the Sun’s glare this month, Mercury reaches superior conjunction (in orbit on the other side of the Sun from the Earth) on October 8th. By month’s end, our solar system’s innermost planet re-emerges in our evening skies.

Uranus comes into opposition (directly opposite the Earth from the Sun) on October 19th. This puts Uranus at its closest to Earth for the year, and it also means that the planet will be visible in the sky all night. It can be found this month in the constellation Pisces.

Neptune will be observable almost all night this month. It can be found this month in the constellation Aquarius.

You will need binoculars or a telescope to locate and observe the small distant planetary disks of Uranus and Neptune.




October 2017 Sky Events – Uranus and Neptune

The motion of the two ice giants, Uranus and Neptune, as they slowly move through Pisces and Aquarius, respectively, in 2017 and beyond.

Charts courtesy of Sky & Telescope


October 2017 Sky Events – Uranus and Neptune

While Uranus makes an 84 year orbit around the Sun, Neptune’s path takes nearly twice as long – 165 years – thus their lazy motion

through our skies is nearly imperceptible.

Charts courtesy of Sky & Telescope

Shortly before sunrise, find Venus and Mars together in the east but taking opposing trajectories. As the month progresses, Venus sinks lower to the horizon, while Mars slowly climbs higher.

On the morning of Thursday, October 5th, the two planets will appear to pass each other (trade positions.) Coincidentally, the pair transition together from the constellation Leo to Virgo in October.

During this close conjunction, the Venus and Mars will be separated by less than one quarter of a degree!





Very Close Conjunction of Venus and Mars

On the morning of Thursday, October 5th, the planets Venus and Mars will be separated by less than one quarter of a degree – a very close conjunction!

To locate the tight pair in the constellation Leo, look low to the eastern horizon about 6:15 a.m. EDT. Optical aid will be necessary to separate the two planets.

While Venus shines at magnitude -3.9, dim Mars glows at +1.8, making Venus about 200 times brighter than its companion!


October 2017 Sky Events – the PlanetsA Crescent Moon with Antares and Saturn

On the evenings of October 22nd

through the 24th, a waxing crescent moon glides near the giant red star Antares, and then passes Saturn.

Select a location with a low view to the southwestern horizon about 7:45 p.m. EDT. Binoculars may help in locating Antares through the twilight.

On this day, Saturn is some 996 million miles behind the Moon, while Antares lies 604 light years in the distance!

Image courtesy of Sky & Telescope


October 2017 Planet Highlights

Planet Avg. Distance from Earth

Constella-tion(s)

Avg. Diameter in arc seconds

Avg. Mag-nitude

Comments

Page 1 of 3

Mercury 1.4

AUs

Virgo & Libra

4.8 -1.0 Reaches superior

conjunction on

Oct. 8th

Venus 1.5

AUs

Leo & Virgo 10.8 -3.9 Shining brightly

low in east at

dawn.

Mars 2.5

AUs

Leo & Virgo 3.8 +1.8 Dim and small,

seen low in the

E about 1 hour

before sunrise.




Constella-tion(s)


Avg. Mag-

nitude

Comments

Page 2 of 3

Jupiter 6.4

AUs

Virgo 30.8 -1.7 Too close to the

Sun to be seen

well. Reaches

conjunction on the

26th.

Saturn 10.5

AUs

Ophiuchus 15.9 +0.5 Observe in the

early evening

SW skies this

month.

Uranus 18.9

AUs

Pisces 3.7 +5.7 At opposition on

Oct. 19th.




Constella-tion(s)


Avg. Mag-

nitude

Comments

Page 3 of 3

Neptune 29.2

AUs

Aquarius 2.3 +7.8 Well positioned

for late evening

observing in

October.


The Moon – October 2017

Unless otherwise indicated, all times are EDT

** The “Harvest Moon” – The full Moon

nearest to the autumnal equinox.

Full Moon** 5th 2:40 p.m.

Last Quarter 12th 8:25 a.m.

New Moon 19th 3:12 p.m.

First Quarter 27th 6:22 p.m.


October 2017 Highlight

A Morning Lunar Occultation ofRegulus on Sunday, October 15th

The waning crescent Moon will occult (pass in front of) the bright, 1st magnitude star Regulus during the early morning hours of Sunday, October 15th.

Regulus (the “heart of the Lion” in the constellation Leo) is the closest bright star to the ecliptic – the apparent path through which the Sun, Moon and planets travel in our sky – and is frequently occulted by the Moon. It shines at magnitude +1.36.

With binoculars or a small telescope, watch this star disappear from view, behind the illuminated limb of the Moon, about 5:29 a.m. EST. It will reappear on the other side of the Moon, from the dark limb, about 6:35 a.m. EST – a 66 minute stellar blackout.

The above times are valid for Asheville, NC and might differ slightly depending on your location.

Look to the E-SE to observe this event in the direction of the constellation Leo. The crescent Moon will be 19% illuminated and 24º above the horizon as the occultation begins.

The times below are approximate for Asheville, NC using EST. Regulus, the Alpha star in the constellation Leo, lies 78 light years

behind the Moon!


October 2017 HighlightA Morning Lunar Occultation ofRegulus on Sunday, October 15th

Regulus

Disappearance about 5:29 a.m. Reappearance about 6:35 a.m.

Regulus

66 minutes later


October 2017 HighlightThe Zodiacal Light – October 17th through 31st

October is one of the opportune months for finding the elusive “zodiacal light” in the early morning sky.

But what is zodiacal light? Zodiacal light is the sunlight reflected from numerous

dust grains located along the plane of the solar system the ecliptic or “zodiac”.

These dust grains are left over from the formation of the solar system (a type of cosmic dust), and their supply is continuously fed by particles from comets and asteroid collisions.

The ecliptic is nearly vertical to the horizon this month providing good viewing opportunities.



Zodiacal light is seen as a “cone” of light that is widest at the horizon.

Look for it low in the east (with an unobstructed view) beginning about two hours before sunrise.

The 40-minute prime viewing window closes about 80 minutes before sunrise.

Pick a very dark location far from artificial lights and without moonlight.

The best dates to see the zodiacal light without interfering moonlight will be from Oct. 1-3 and 17-31.

In this fall season, when the zodiacallight is visible in the eastern morning sky, it is often called the “false dawn”.

Zodiacal Light and the Milky Way





The Orionid meteor shower peaks before dawn on the mornings of Friday, October 20th through Sunday, October 22nd, with the best chance of catching meteors being during the pre-dawn hours of Saturday the 21st.

This shower typically produces a modest 10 to 15 visible meteors per hour under ideal conditions, lasting for several days.

Orionids move swiftly through the sky, striking the atmosphere at 41 miles per second, and often leave brief glowing trails.

The Orionids are caused by debris from the orbit of Halley’s Comet. In fact, the Earth passes through this debris field twice per year, creating both the Eta Aquariid meteor shower in May and October’s Orionids!

The first recorded observation of the Orionids was by the Chinese in the year 288 A.D.

Orionid Meteor Shower



Like all meteor showers, the Orionids are named after their radiant, the place where they appear to originate in the sky (near the hunter’s club in the constellation Orion.)

In October, you’ll have to rise early to catch this meteor shower. The constellation Orion doesn’t appear in the east until well after midnight, meaning the peak observing window will be limited to the hours between 2:00 a.m. and 5:00 a.m., when the constellation is higher in the sky but before the onset of dawn’s light spoils the show.

The good news is that because this meteor shower peaks near the New Moon in 2017, moonlight will not interfere with pre-dawn observing!

The peak lasts for several days, so try your luck on the mornings between Friday, October 20th and Sunday the 22nd.





Illustration courtesy of Sky & Telescope


October 2017 HighlightAsteroid 2 Pallas Is Nearest Earth

2 Pallas, the second asteroid to be discovered (after Ceres), reaches opposition on October 29th. At opposition, it is opposite the Earth from the Sun and closest for the year to Earth in its orbit.

Located in the asteroid belt between the orbits of the planets Mars and Jupiter, Pallas can be observed this month with optical aid, seen in the foreground of the southern hemisphere constellation Eridanus, the River – some 1.7 astronomical units away, or 158 million miles.

Discovered in 1802 by Heinrich Wilhelm Olbers, Pallas is the third-most massive asteroid, after Ceres and Vesta.

Shining at magnitude 8.3, try to locate this dim asteroid belt object with a telescope this month.



While NASA’s Dawn probe has visited both Ceres and Vesta, because of Pallas’ highly eccentric orbit, there are no current plans

to explore the asteroid by spacecraft.

The Moon and the largestknown asteroids, for scale

NASA artist’s interpretation of Pallas, based on Hubble image

Pallas orbits the Sun once every 4.6 Earth years.



Use the chart and the link below to help you locate and observe Pallas for your location, date and time this month.

At opposition on October 29th, 8.2 magnitude Pallas will be near the star Angetenar in the constellation Eridanus.

Pallas Chart Link

Angetenar

http://www.heavens-above.com/MinorPlanet.aspx?desig=2&lat=0&lng=0&loc=Unspecified&alt=0&tz=UCT

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Astronomy Club of Asheville October 2017 Sky Events · · 2017-10-01Astronomy Club of Asheville October 2017 Sky Events ... Leo & Virgo 10.8-3.9 Shining brightly low in east at