Moon Will Hide Jupiter Before Dawn on Oct. 6: When and Where to Watch
A 20%-lit crescent moon will pass in front of Jupiter before dawn on Oct. 6, and skywatchers in eastern and central North America can see it, sources say.
What is happening
The moon is about to block the giant planet from view. Astronomers call this a lunar occultation, from a Latin word meaning "to conceal."
The slender crescent will rise at around 2:30 a.m. local daylight time, with brilliant Jupiter shining close to its sunlit side. As the pair climbs, the moon gradually closes in on the planet. Jupiter then slips behind the moon's bright edge.
About an hour or so later, Jupiter emerges from behind the moon's dark edge, which is dimly lit by earthshine. Astronomy.com calls it the best Jupiter occultation for North America since 2004.
Where you can see it
Viewers in the eastern and central U.S. and southern Canada will see the event in full darkness. Eastern New York State, New England and Atlantic Canada are especially favored, with the moon about 20 degrees high at disappearance and about 30 degrees when Jupiter reappears. A clenched fist at arm's length spans roughly 10 degrees.
Farther south and west, the moon sits lower. Across the western Great Lakes, the eastern Great Plains and the central Gulf Coast, it is about 15 to 20 degrees high at reappearance.
Along a line from roughly central Montana to southeastern Texas, the disappearance happens around moonrise. The moon is only 5 to 10 degrees up when Jupiter reappears. West of that line, only the reappearance is visible, so scouting a spot with a clear eastern horizon is wise. West of a line from just west of Helena and Salt Lake City to east of Tucson, no occultation is visible.
Strips across northern Montana and southern Canada will see only a partial occultation, with the moon grazing Jupiter's disk. Live Science also notes the Caribbean will see the event before dawn, while parts of Africa will see it in daylight.
How it will look
Jupiter is not a pinpoint like a star, so it will fade out and return over about a minute as the moon's edge crosses its disk. Sources differ slightly on equipment. Space.com says binoculars or a telescope are needed to watch the disappearance but the reappearance is easy to see by eye. Live Science says no telescope is needed for either, though optics make it more dramatic.
Where no occultation occurs, the moon and Jupiter will still form a very close pair in the predawn sky.
What it means for you
Check the exact disappearance and reappearance times for your city before going out, because they vary by location. Live Science lists times for 10 major cities from the International Occultation Timing Association, and Space.com's maps let you estimate local times in Universal Time. To convert, subtract 4 hours for Eastern, 5 for Central and 6 for Mountain daylight time. If you want photos, Live Science suggests a smart telescope imaging the moon.
Also read Tropical Storm Isaias Could Form in the Gulf This Week; Texas to Florida Urged to Watch
Quick answers
Do I need a telescope to see Jupiter disappear?
Not strictly, but binoculars or a small telescope make it far better. Space.com says the disappearance needs optics, while the reappearance is visible to the naked eye.
When is the next Jupiter occultation in North America?
The next lunar occultation of Jupiter visible from North America is on Nov. 27, 2037, according to the sources.
Can I see it from the U.S. West Coast?
No. No occultation is visible far west of Salt Lake City and Tucson. Jupiter will still sit just above the crescent moon as they rise.
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