July's full moon, nicknamed the Thunder Moon, occurs this week on Tuesday, July 16, at 5:38 p.m. EDT (2138 GMT), 50 years to the day of NASA's Apollo 11 moon mission launch!
About 7 minutes before the full moon's peak, the moon will start to dip into Earth's shadow, kicking off the last lunar eclipse of the year. Meanwhile, Saturn will be making a close approach to the moon in the night sky.
A lunar eclipse occurs when the moon is on the opposite side of the earth from the sun and passes through the shadow of the Earth. This doesn't happen every time the moon is full, because the orbit of the moon is slightly askew from the plane of the Earth's orbit, and the moon usually "misses" the Earth's shadow. During a partial lunar eclipse, the Earth's shadow only covers part of the lunar disk; so one doesn't get the "blood moon" effect one sees during total lunar eclipses.
The moon will not turn red during Tuesday's eclipse; rather, a chunk of the moon will gradually begin to appear darker starting at 2:43 p.m. EDT (1843 GMT) until maximum eclipse at 5:30 p.m. EDT (2130 GMT), after which the moon will begin to exit Earth's shadow. The last penumbral phase of the eclipse ends at 8:17 p.m. EDT (0017 GMT on July 17).
How to see the eclipse
Observers in the U.S. won't see the eclipse — the moon doesn't rise in New York City until 8:29 p.m. local time, according to timeanddate.com. Moonrise times are similar as one moves south; in Miami, it rises at 8:17 p.m. local time. Farther west, the eclipse happens well before moonrise as well. (If you can't see the eclipse in person, check back with Space.com on the day of the eclipse for live webcasts.)
The eclipse will be visible to observers in the Caribbean, South America, Europe, Africa and Asia, according to EclipseWise.com. It will begin when the moon enters the penumbra, which is the lighter part of the Earth's shadow, at 2:43 p.m. EDT (1843 GMT). The penumbral phase of a lunar eclipse is usually hardly noticeable; even careful observers will only see a slight darkening of the moon. At 4:01 p.m. EDT (2001 GMT) the moon will enter the umbra, the darkest and most easily visible part of the Earth's shadow. At 6:54 p.m. EDT (2254 GMT) the moon will exit the umbra, and at 8:17 p.m. EDT (0017 GMT on July 17) the moon will emerge from the penumbra.
This eclipse will have a maximum magnitude of 0.65, which means 65 percent of the moon's diameter will be covered by the shadow of the Earth. Not every location will see that; the places on Earth which will see a maximal eclipse are in eastern South America, central and southeastern Europe, the Middle East, Africa and western India.
According to timeanddate.com, South American sky watchers will see the moon rise just as it enters the umbra; the magnitude of the partial eclipse over most of the continent will be less than 0.65. For example, in Cuzco, Peru, the eclipse begins while the moon is still below the horizon. Moonrise is at 5:34 p.m. local time and the maximum eclipse there will occur at 5:36 p.m., when the entire moon has emerged from the horizon. Peruvians will only see 25 percent of the moon's diameter covered, and the moon emerges from the umbra at 5:59 p.m. In Rio de Janeiro, moonrise is at 5:17 p.m. local time, and the maximum eclipse is at 6:30 p.m., reaching a magnitude of 0.65. The moon will exit the umbra at 7:59 pm. local time.
Going further east, the eclipse starts after moonrise. In Vienna, Austria, the penumbral phase of the eclipse coincides with moonrise at 8:43 p.m. local time. The umbral phase starts at 10:01 p.m., and maximum eclipse will occur at 11:30 p.m. The moon emerges from the umbral portion of Earth's shadow at 12:59 a.m. local time on July 17, and the penumbral phase lasts until 2:17 a.m.
In southern Africa, the moon will be high in the sky and the entire eclipse will be visible — weather permitting, of course. In Cape Town, South Africa, the eclipse times will be the same as in Vienna, as the two cities are in the same time zone. Cape Town, though, is in the Southern Hemisphere, where it is winter and the sun sets earlier — at 5:55 p.m. local time. So, when the umbral phase begins, the moon is a good 50 degrees above the horizon.
North Americans won't get an eclipse, but as the full moon travels across the sky it will enter conjunction — sharing the same celestial longitude — with the planet Saturn. The moon will pass only about one-fifth of a degree to the south of the ringed planet on July 16 at 3:15 a.m. EDT (0715 GMT), according to the skywatching site In-the-sky.org. If that happens during the daytime from your observing location, don't worry — the cosmic pair will appear pretty close together in the sky for the rest of the night after that.
Several other planets are visible on the night of the full moon. Jupiter, which is east of the moon and Saturn on July 16, will be just north of the bright star Antares in the constellation Scorpius. Mars will be setting soon after the sun does, at 9:15 p.m. local time in New York City. Venus is a "morning star," rising in the east less than an hour before sunrise.
How the Thunder Moon got its name
Native peoples in the Americas had various names for July's full moon; the names reflect that in the Northern Hemisphere it is summer and in the Southern Hemisphere it is winter. The name "Thunder Moon" (per the Old Farmer's Almanac) was adapted from native peoples in what is now the United States, where summer is thunderstorm season, especially in the northeast and Midwest.
However, the July full moon had other names. According to the Ontario Native Literacy Coalition the Ojibwe called it the Raspberry Moon, while Cree called it the Feather Molting Moon, as some birds start to molt at that time of year.
The Māori of New Zealand used a lunar calendar called the maramataka, which measured months between successive new moons. The July-to-August lunar month (which this year spans the new moons from July 2 to Aug. 30) is called Here-turi-kōkā, meaning "The scorching effect of fire is seen on the knees of man." according to the Encyclopedia of New Zealand. This lunar month was, to the Māori, the third month of the year.
In the traditional Chinese lunar calendar, the full moon of July 2019 will fall in the sixth month, called Héyuè, or the Lotus month, named for the eponymous flower which blooms in the summer.
Aside from evocative names for full moons in July, lunar eclipses have had various associations in different cultures. The Mayans and Incas saw the lunar eclipse as a manifestation of a jaguar eating the moon, according to a story in National Geographic titled "Lunar Eclipse Myths From Around the World." Western culture have often perceived eclipses as bad omens, but the Hupa of California saw eclipses as the moon being attacked by his (the Hupa saw the moon as male) pets and then healed by his wives.
In some Islamic traditions there is a prayer associated with lunar eclipses called the Salat-al-Kusuf, which should be accompanied by doing good deeds. Eclipses were seen as a way for Allah to strike fear in the hearts of the congregations (Muhammed is purported to have explicitly told his people that eclipses are unrelated to human lives, and reflect the will of Allah).
Editor's Note: If you capture an amazing photo of the Full Thunder Moon eclipse and want to share it with Space.com for a story or gallery, please send images and comments to managing editor Tariq Malik at email@example.com.
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