Moon

Jupiter vanished behind the moon on October 6 in the best North American occultation since 2004

Jupiter disappeared behind the moon's slender crescent before dawn on October 6, in an occultation that Astronomy magazine calls the best view of the event for North America since 2004. The planet slipped behind the moon's bright limb and emerged from its dark, earthlit edge roughly an hour later, with the full occultation visible across the eastern and central United States and adjacent southern Canada, according to Space.com and Astronomy.

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A once-in-a-decade alignment before sunrise#

The waning crescent moon, just 20% illuminated and about four and a quarter days from new phase, rose around 2:30 a.m. local daylight time with Jupiter shining near its sunlit side, Space.com reports. As the pair climbed higher, the moon drew closer to the planet until it slipped in front of Jupiter's disk, a process Space.com says takes roughly a minute for both disappearance and reappearance because Jupiter's apparent diameter is one fifty-eighth that of the moon.

Live Science describes the event as a once-in-a-decade alignment that will not happen again for 11 years, with the occultation visible before dawn across much of the eastern and central U.S., Canada and the Caribbean, while parts of Africa saw it during daylight, according to In-The-Sky.org as cited by Live Science.

NASA says the occultation began around 4 a.m. EDT, with Jupiter's glow slipping behind the moon's thin crescent, vanishing for about an hour, then reappearing, and adds that the event was visible to the naked eye, though binoculars offered a better chance of catching Jupiter's own moons blink out and back in.

Farther west the view differed. From Denver, Jupiter's disappearance was not visible, but skywatchers could catch the planet's reappearance at around 3:11 a.m. MDT, Space.com reports, while across much of the western U.S., including Washington, Oregon, California and most of Arizona, the occultation had already ended by the time the moon and Jupiter rose.

A morning of two planetary meetings#

The occultation followed a lunar pairing with Mars the previous morning, Sunday October 5, when the crescent moon sat beside Mars in the eastern sky before dawn, according to BBC Sky at Night Magazine. Observers in northern Canada saw a lunar occultation of Mars that morning, with the Red Planet disappearing behind the moon, the magazine reports.

Photographers captured the October 6 event across North Carolina and Pennsylvania, Space.com reports, with astrophotographer Peter Zay photographing Jupiter shortly before it slipped behind the lunar crescent and again as it emerged from the moon's night side. Zay told Space.com in an email, "Astrophotography is unforgiving," adding that he avoids composite techniques and instead relies on planning around gear, weather, location and timing.

Observers outside the path of full occultation still saw Jupiter shine just a few degrees from the moon because of parallax, the effect that makes nearby celestial objects appear in slightly different positions depending on the viewer's location on Earth, Space.com explains.

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