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Waxing toward full Hunter’s Moon

Tonight – October 14, 2016 – if you’re in the Northern Hemisphere, the moon is waxing toward a full Hunter’s Moon.

Full moon will come on October 16 at 4:23 UTC; translate to your time zone. At United States time zones, that places the time of the full moon on October 16 at 12:23 a.m. EDT – and on October 15 at 11:23 p.m. CDT, 10:23 p.m. MDT or 9:23 p.m. PDT.

The times don’t really matter. No matter where you live worldwide, look for a full-looking moon in the east as the sun goes down over the next several days. This full or full-looking moon will cross our skies throughout the night, as seen from around the globe.

For us in the Northern Hemisphere, this Hunter’s Moon will be displaying its unique features, characteristic of this time of year. That is, the inclination of our moon’s orbital plane to the celestial equator will cause the moon to rise further north along the eastern horizon for nearly all of the upcoming week. For northerly latitudes in the Northern Hemisphere, these more northerly moonrises reduce the lag time between successive moonrises, which is the legacy of the Hunter’s Moon.

Meanwhile, in the Southern Hemisphere, the opposite is taking place. The more northerly moonrises along the horizon mean a longer-than-average time between successive moonrises, from night to night, over the coming nights. Read more:

2016 has a ‘super’ Hunter’s Moon

Minor lunar standstill makes a subtle Hunter’s Moon in 2016

It so happens that Earth swings closest to the planet Uranus for the year on October 14; that is, the distance between our two worlds is least for 2016 on this date. Then, on October 15, Uranus will be at opposition – located most opposite the sun from Earth – for 2016. By coincidence, Uranus is not far from the moon on the sky’s dome on the nights of October 14, 15 and 16.

The nearness of the Uranus to this full and full-looking moon means it’ll be lost in the moon’s glare for amateur observers.

Even on a dark moonless night, Uranus appears – at best – as a faint speck of light to the eye alone. You need exceptional vision to see this distant world without an optical aid, even under the best conditions. Here’s a good sky chart, if you want to see Uranus.

Just be aware Uranus is up there, near this nearly full moon. And think about the fact that Uranus is a real oddity in that it goes around the sun “sideways,” with its rotational axis almost lining up with its orbital plane. In contrast, the rotational axis of our planet Earth is inclined about 23.5o out of perpendicular to our orbital plane.

The orbital planes of Uranus’ major moons pretty much coincide with the planet’s equatorial plane. That’s in spite of the fact that Uranus’ equatorial plane is nearly perpendicular to the plane of its orbit around the sun.

As a general rule, the major moons in our solar system orbit their parent planets above their respective planets’ equators. There are a few exceptions: Saturn’s moon Iapetus, Neptune’s moon Triton – and, perhaps most significantly to us earthlings: Earth’s moon.

Our moon doesn’t orbit the Earth above our planet’s equator (0o latitude). Rather the moon’s orbital plane is inclined to the Earth’s equatorial plane. The moon’s orbital path took the moon from its maximum declination of 18.5o south of the celestial equator on October 8, and then the moon will swing to its maximum declination of 18.6o north of the celestial equator on October 21.

If the moon’s orbital plane – like that of Uranus’ moons – coincided with our planet’s equatorial plane, our moon would always rise due east and set due west – meaning no Hunter’s Moon in autumn. The Hunter’s Moon will come on the night of October 15-16, as the moon is going eastward as well as northward in its orbit.

Read more: In 2016, Hunter’s Moon also a supermoon

Uranus and moons

Near-infrared image of the ice giant Uranus , its rings and some of its moons. Image credit: European Southern Observatory

Bottom line: To the eye, the moon will appear nearly full as the sun sets on October 14. Watch for it in the east as soon as the sun goes down. Plus Uranus is near the moon on the sky’s dome on the nights of October 14, 15 and 16, but don’t expect to see this distant world without a careful search and optical aid.

Bruce McClure