Are you ready for the Great American Eclipse of 2017? Even though there has been a fair amount of media coverage, some people are not aware that the United States will experience a major total solar eclipse in a little more than a month, on Monday, Aug. 21.
Eclipses occur when a moon or planet moves into the shadow of another object. In the case of a solar eclipse, the new moon’s shadow falls on the Earth. During a lunar eclipse, the full moon passes through the Earth’s shadow.
Eclipses have a reputation for being rare but somewhere in the world 2 to 5 solar eclipses occur each year. Lunar eclipses, when they occur, can happen up to 3 times in a year. Total solar eclipses occur on average every 18 months. What makes eclipses seem uncommon is that you have to be in the right place at the right time to see them. Lunar eclipses are easier to view because they are visible anywhere the moon is located above the horizon. Solar eclipses are best visible where the relatively narrow shadow of the moon touches the Earth.
In New Jersey, it has been quite a while since we’ve had a good view of a solar eclipse. The best one most recently was 1994, when 84 percent of the sun was blocked. The last fairly decent solar episode visible here was a partial eclipse on Christmas Day 2000, when 55 percent of the sun was covered by the moon. Because most people missed seeing the sunrise partial eclipse of 2013 due to cloud cover, it has been 17 years since we’ve witnessed a good one.
During the Aug. 21 eclipse, the shadow of the moon will cross the United States from coast to coast, something that hasn’t occurred since 1918. The eclipse starts in the Pacific Ocean, hits the west coast in Oregon and moves diagonally across the continent, passing north of Kansas City, south of St. Louis, then right through Nashville, Tenn., and Columbia, S.C. It then leaves the coast just north of Charleston and heads out into the Atlantic Ocean.
A visualization of the moon’s shadow crossing the United States during the eclipse. (NASA/GSFC/Genna Duberstein)
The dark inner shadow of the moon, the umbra, is only 70 miles wide. If you are in that shadow, you will see the moon completely cover the disk of the sun, revealing its beautiful outer atmosphere. This narrow path is the only place a total solar eclipse will be visible.
If you do want to see the total phases of this event, you need to make your plans as soon as possible. One expert estimates as many as 7 million people may try to go see this event. With that many people traveling and a lot of people on vacation in late August, there could be some serious traffic jams on major highways leading to these areas. Michael Zeiler and Polly White’s eclipse website greatamericaneclipse.com has some particularly good maps and advice on how to get to the centerline of the eclipse path. Many hotels and campgrounds are already full, so don’t wait to make your arrangements. To help make your plans, check out NASA’s handy interactive map and printable maps for each state on the path.
Weather will be a very important factor. South Carolina may be an appealing viewing spot for people on the east coast due to its proximity, but tropical storms and hurricanes can impact this area. Meteorologists recommend heading west where it’s more likely you will have clear skies. In general, states west of the Mississippi River have the best chance. Jay Anderson’s Eclipsophile website is one of the best for eclipse weather forecasts. Although long-range forecasts are obviously not very accurate, this can at least give you an idea of where the best places to view might be.
If you can’t make it to the centerline, the partial eclipse is visible all across the entire country. Here in the Garden State, we are too far north for totality, but we will see 73 percent of the sun covered by the moon. This is not as good as 1994, but better than the one in 2000.
Next week, we’ll explore more in depth how and when to view the eclipse in New Jersey, as well as how to protect your eyes during the event.
In the meantime, if you would like to read more about this eclipse, visit NASA’s excellent Eclipse 2017 website. Also note that the Newark Museum will be running a planetarium show “Eclipse: The Sun Revealed,” Wednesday to Saturday at 3 p.m. through Aug. 18. For more information, visit Newarkmusuem.org.
Kevin D. Conod is the planetarium manager and astronomer at the Newark Museum’s Dreyfuss Planetarium. For updates on the night sky, call the Newark Skyline at (973) 596-6529.