March 7 is the date of a new moon, which means that on that night the sky will be dark and stargazers will not be hindered at anytime during the night by bright moonlight.
Thirty-eight years ago, in the year 1970, new moon also fell on March 7. This circumstance, however, is far from being a coincidence. Rather, it's related to what astronomers refer to as a synodic month: the return of the moon in its orbit relative to the sun in the sky. In fact, the Greek astronomer Meton (born about 460 B.C.), independently discovered that 235 synodic months is almost exactly equivalent to 19 years: what we now call the Metonic cycle. So, going back two Metonic cycles (19 x 2 = 38) brings us to the new moon of March 7, 1970.
But that was a very special new moon, for it also brought with it one of nature's greatest spectacles: a total eclipse of the sun.
At sunrise on that day, the shadow of the moon touched down on the Earth at a point in the southern Pacific Ocean. Then, for a period of slightly more than three hours, the shadow raced first eastward, then northeastward across the North American continent, leaving the Earth at sunset in the North Atlantic Ocean, midway between America and Europe. Part of that narrow shadow path crossed the heavily populated east coast of the United States; there were an estimated 60 million people who were either fortuitously positioned within the path of totality or were within a day's drive of reaching it. Not since 1954 had there been an opportunity to see a total solar eclipse in such easily accessible and widespread areas of the contiguous United States. Granted, there were a few limited opportunities such as in 1959 and 1963, but those eclipses were visible only in the extreme northeastern parts of the country, and their areas of visibility were either limited or difficult to reach.
In contrast, the 1970 eclipse swept across the southeastern and mid-Atlantic U.S., passing over many small communities and near or directly over several large metropolitan areas. Savannah, Charleston and Norfolk were within the path of the total eclipse: Tallahassee and Wilmington (North Carolina) were on the edges of the path, and Jacksonville, Augusta and Richmond were within easy driving distance of totality. This entire region was well served by interstate highways, while public transportation into or near the eclipse path was excellent and facilities for travelers were abundant.
In many ways, the 1970 eclipse was quite special. It was the first total solar eclipse to be observed from a satellite: NASA's ATS-3, from its synchronous orbit position 22,300 miles (35,880 km.) above the equator. It was also the first solar eclipse to which three television networks (ABC, CBS, NBC) devoted major coverage, in color.
Where were you?
Although nearly four decades have passed, I'm sure that quite a few readers are able to recall in vivid detail just what they were doing on that first Saturday of March 1970. Perhaps you saw the sun's corona from a beach in Virginia, a tobacco field in South Carolina or a sand spit on Cape Cod. Fortunate observers will long remember the deep blue sky at totality, brilliant Venus and the crisp silvery corona. Or perhaps you took a long trip to some eclipse site in Florida or Georgia only to be clouded out, or had to wait for drifting clouds to move away from the sun. Many people witnessed their very first total eclipse on that memorable Saturday afternoon and became "eclipse junkies" for life.
On the Solar Eclipse Mailing List, one member recently mused: " ... ever since then, I have gone to almost every total solar eclipse that there has been. It reminds me of the way the people were called to Devils Tower in 'Close Encounters of the Third Kind.' It's like a sickness, a very expensive terrible habit, drawn by a power that makes me want to drop everything and head for the other side of the world if need be to see the next one. It's a terrible habit, and I have found no way to kick it ... very sad."
I'd like to hear about the experience of others who "basked in the moon's shadow" that day.
Waiting for the next one?
People often ask about when the next total solar eclipse will cross the contiguous United States. At the moment, the U.S. is in the midst of a long eclipse drought. The last total solar eclipse was on February 26, 1979, and was visible over parts of the Pacific Northwest and the northern Rockies. The drought will come to an end on August 21, 2017 when the moon's shadow finally returns to the United States, followed by yet another on April 8, 2024.
The latter will come just over 54 years after the 1970 eclipse and belongs to the same eclipse family (known as a "saros"). That 2024 eclipse will be truly a fine one with nearly four and a half minutes of totality near the middle or "noon" point of the eclipse path in central Texas. The path then races all the way up into northern New England. The "drought busting" eclipse of 2017 will run all the way across the country from Oregon to South Carolina with the noon point in central Missouri where the sun will be completely covered for more than two and a half minutes.
Statistically, any one specific spot on Earth will have a wait of roughly four centuries between total solar eclipses. But the paths of the 2017 and 2024 eclipses will actually overlap each other in a small region that includes parts of the states of Kentucky, Missouri and Illinois. Indeed, if you live in Paducah, Cape Girardeau or Marion, be advised that astronomy's greatest road show will be coming to your town twice ... over a time span of a little less than seven years.
Mark your calendars!
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Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.