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Have you ever noticed that when there is a solar or lunar eclipse, an eclipse of the other variety comes two weeks before or after? Sometimes we will even have three eclipses in less than a month.
Just such a situation is happening right now. We have already had a partial eclipse of the sun this month, on Friday the 13th, visible only from parts of Antarctica, Tasmania, Australia and a very narrow part of New Zealand. Another partial eclipse of the sun will take place on August 11th; it will be visible to those living in northern Europe as well as to much of central and eastern Asia. Even parts of the far north and east of Canada will have a glimpse of it at sunrise.
And right in the middle, between the two solar eclipses, there will be a total eclipse of the moon on July 27th. [Blood Moon 2018: Longest Total Lunar Eclipse of Century Occurs July 27]
This is because that day, the moon will cross the ecliptic, the line that marks the path of the sun around the sky. If the moon crosses the ecliptic when it is full, we will have an eclipse of the moon; if the moon crosses the ecliptic when it is new, we will have an eclipse of the sun. Incidentally, it is the reason why the path of the sun in the sky is called the "ecliptic" – for "eclipse"!
And whenever a full or a new moon crosses the ecliptic from one side of the lunar orbit, it also crosses this line from the opposite side of the orbit lunar, two weeks earlier or two weeks later. We call this period an "eclipse season".
Three for the price of two
We usually get two eclipses during an eclipse season. But as we have just seen, during the current eclipse season, not two, but three eclipses will take place in a single synodic month of 29.53 days – the time required to move from a new moon to the next. ;other.
The total lunar eclipse of July 27 will be particularly noteworthy, as the satellite will pass just north of the middle of the Earth's shadow. In fact, the moon will reach the descending node of its orbit – the point where it crosses the ecliptic from north to south – only 138 minutes after the arrival in full phase, resulting in a nearly total central eclipse .
For this reason, the two new moons flanking the full moon of July 27 will come close enough to the opposite (ascending) node of the moon to allow the moon to marginally overshadow the sun both times. Therefore, we get three eclipses instead of the usual two
A slow little moon + a big shadow = a long eclipse
Another artifact of the near central passage of the moon through the shadow of the Earth is that the totality will last. unusually long time. In fact, the path of the moon through the shadow is just a factor in achieving a long lasting total phase; the distance of the moon also has an effect. About 14 hours before it is full, the moon will be at its farthest point of Earth (apogee), a distance of 406,223 kilometers, and the moon will move the slowest in its orbit the most away from the Earth.
This also translates into a full moon that is much smaller than average; in fact, it will be the smallest full moon of 2018. This eclipse will take place three weeks after the arrival of the Earth at the aphelion, the farthest point of the planet's orbit, when the shadow of the Earth seems the greatest.
So, adding up all of this, we will have a small moon, moving slower than usual, going almost straight in the middle of a larger shadow than the normal Earth. This will result in a disproportionately long eclipse whose total phase will last 1 hour and 43 minutes, just 4 minutes from the longest possible duration. According to "The Five Lunar Lightning Cannon: (-1999 to +3000)" by Fred Espenak and Jean Meeus, it is the longest total lunar eclipse that the Earth will see until June 9, 2123. [19659002] The average duration of a total lunar eclipse is about 50 minutes
North America is excluded
Now for bad news, if you live in America North or Central: None of this eclipse will be visible in these places – not even the partial stages – the entire event will take place during the hours of noon and afternoon, when it will be the day and the moon will be at below the horizon.
If, however, you are in Europe, Africa or Asia, you will see the event. The moon will appear directly above a point located a few hundred kilometers off the east coast of Madagascar in the Indian Ocean.
Much of Japan and East of Australia will see the moon go down while she is in total eclipse. The central and eastern parts of South America will see the moon rise during or after all.
Do not Forget March
With the moon totally overshadowed, something else in the sky will be disputing the attention: March. On the day of the eclipse, Mars will be at the opposite of the sun. Brilliant with a dazzling yellow-orange glow, this planet will be located about half a dozen degrees below the moon. Some long-time eclipse enthusiasts may remember a similar marriage of a moon totally overshadowed with Mars to an exceptionally bright opposition on August 6, 1971. This eclipse, like this one to coming, was only visible from the Old World
.
The next total lunar eclipse will take place on Sunday, January 20, 2019.
As if to try to compensate the North Americans who will miss the show this summer, the next lunar eclipse will strongly favor the Western Hemisphere . . From most of the United States and Canada, the eclipse will be visible from beginning to end, and all will occur during the opening hours of the "prime time". In addition, the totally eclipsed moon will appear very high in the winter sky.
It will also perform during Martin Luther King Jr.'s three-day weekend, ensuring a wide audience of audiences nationwide. This will be the first time that a total lunar eclipse will occur during a holiday weekend since May 1975. In short, it will likely be a very popular and highly anticipated heavenly event.
I hope the weather in your area will cooperate. Mark Your Calendars
Publisher's Note: If you take a picture of the total lunar eclipse on Friday and want to share it with Space.com for a story or a photo gallery, send your comments and images to spacephotos @ space.com.
Joe Rao is an instructor and guest speaker at the Hayden Planetarium in New York. He writes on astronomy for Natural History magazine, Farmer's Almanac and other publications, and he is also a camera meteorologist for FiOS1 News in the Lower Valley of the United States. Hudson in New York. Follow us on @Spacedotcom Facebook and Google+. Original article on Space.com.
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