Eclipses Of 2017: A Sneak Preview

All the moon’s fault! Diagrams showing how lunar (left) and solar eclipses happen. Each depends on a neat alignment of the sun, moon and Earth. Solar eclipses happen at new moon; lunar eclipses always at full moon. Credit: Starry Night with additions by the author

With the 2017 in sight, let’s look at some of the most anticipated events of the year — I’m talking eclipses! Four of them are on tap in the coming year, two widely visible across North America and two to delight skywatchers in the southern hemisphere.

* February 10 — Penumbral lunar eclipse — Visible in North America (clicking on the date will give you local details for each eclipse)

The moon passes through Earth’s outer shadow, the penumbra, on Feb. 10. In the umbra, the sun is blocked from view, but the outer shadow isn’t as dark because varying amounts of sunlight filter in to dilute the darkness. Times are Central Standard. Credit: F. Espenak, NASA’s GFSC

During a familiar partial or total lunar eclipse, the full moon first passes through the Earth’s outer shadow, called the penumbra, before entering the dark, interior shadow or umbra. Because the moon’s orbit is tilted about 5° from the plane of Earth’s orbit, it rarely lines up for a perfect bullseye total eclipse: Sun – Earth – moon in a straight line in that order. Instead, the moon typically passes a little above or below (north or south) of the small, circle-shaped shadow cast by our planet, and all we get is a full moon with no eclipse. Or it clips the outer edge of the shadow and we see a penumbral eclipse.

Yes, that shadow. It may grow during twilight to cover the sky as seen from the ground (it’s right over our heads!), but at the moon’s distance of 239,000 miles, the entire shadow — penumbra and umbra combined — span just 2.5° of sky or about the width of your thumb held at arm’s length.

This map shows where the eclipse will be visible. All of North America will see it except western Alaska. Credit: F. Espenak, NASA’s GFSC

February’s eclipse will be worth watching because the moon travels deep within the penumbra, practically brushing the outer edge of the umbra. The lower left (eastern) side of the moon will appear obviously gray and blunted especially around maximum eclipse as it rises in the eastern sky that Friday evening over North America. Nearly all of the U.S. plus Canada, Europe, Africa, S. America and much of Asia will see all or part of the eclipse. For the U.S., the eastern half of the country gets the best views. Here are Central time zone times for the different stages. Add an hour for Eastern, subtract one hour for Mountain and two hours for Pacific times. UT stands for Universal Time, which is the same as Greenwich or “London” Time except when Daylight Saving Time is in effect:

Eclipse begins: 4:34 p.m. (22:34 p.m. UT)
Maximum eclipse (moon deepest in shadow): 6:43 p.m. (00:43 UT Feb. 11)
Eclipse ends: 8:53 p.m. (2:53 UT Feb. 11)

February 26 — Annular solar eclipse — Not visible in North America

Sequence showing the sun before, during and after an annular or “ring of fire” eclipse. This eclipse pictured above happened over Urbana, Ill. on May 10, 1994. Because the sun is never fully covered by the moon, you’ll need a safe solar filter or eclipse glasses for viewing 2017’s annular eclipse. Credit: Bob King

During a solar eclipse, the new moon passes directly between the sun and Earth, biting into the solar disk blocking it from view for several minutes before releasing it to shine free once again. When the lineup is slightly askew, again due to the moon’s tilted orbit with respect to Earth’s, our satellite only covers part of the sun for a partial solar eclipse. An annular or “ring of fire” eclipse occurs when the moon passes centrally over the sun but is too small to completely cover it, leaving a thin but brilliant ring of sunlight remaining at maximum eclipse.

The moon’s apparent size waxes and wanes with its changing distance from Earth as it sweeps along its elliptical orbit. Turns out, the moon will be at apogee, its most distant point in its orbit, on that very day, and so appear smaller than usual, not quite big enough to totally eclipse the sun. This eclipse will only be visible along a path crossing from southern South America to southern Africa with a partial eclipse widely visible on those continents and Antarctica. Of course, someone or several someones will live stream the event, so no matter where you live, you won’t miss out. I’ll have more details as we get closer to the time.

Times for Facundo, Argentina:

Start of partial eclipse: 12:24 UT
Start of annular eclipse: 13:38 UT
End of annular eclipse: 13:39 UT
End of partial eclipse: 15:00 UT

* August 7 — Partial lunar eclipse — Not visible in North America

During a partial lunar eclipse, the Earth’s inner umbral shadow takes only a “bite” out of the full moon as it did in this eclipse from July 1999. Credit: Bob King

Only about 25% of the moon will be covered by the umbra during this second and final lunar eclipse of the year. To see it, you’ll need to be looking up that Monday night from European, African, Asian and Antarctic skies. Again, live streams of this eclipse will become available, so we can all watch it.

Penumbral eclipse begins: 15:50 UT
Partial eclipse begins: 17:23 UT
Maximum eclipse: 18:20 UT
Partial eclipse ends: 19:18 UT
Penumbral eclipse ends: 20:51 UT

* August 21 — Total solar eclipse — Visible in North America — Premier event!

The gray strip marks the 70-mile-wide path where you can see the sun totally eclipsed on Monday August 21, 2017. Places outside the path will see a partial eclipse. Credit: Xavier Jubier

We have a winner! Everyone in the U.S., much of Canada, central and the northern half of S. America will see at least a partial solar eclipse that Monday. For viewers located along a narrow path that runs southeastward from Oregon through Idaho, Wyoming, Nebraska, Kansas, Missouri, Illinois, Kentucky, Tennessee, Georgia, North Carolina and South Carolina, a total solar eclipse will be visible. At maximum, the moon will block the sun from view for 2 minutes 40 seconds. Everyone outside of the path will see a partial eclipse; the closer you live to the path, the greater the partial eclipse.

Since the event happens in the middle of the summer vacation season when most of us are mobile already, it’s destined to become one of the most widely viewed eclipses in decades. Like myself, many plan to fly or drive to be inside the path of totality. Cities that lie in the path include Salem, OR; Lincoln, NE; Kansas City, Jefferson City and St. Louis, MO; Nashville, TN and Columbia and Charleston, SC. That’s millions of people right there, and all they have to do is walk out the door!

Among the highlights of seeing a total solar eclipse is being able to look directly at the sun (covered by the moon) and view its spectacular outer atmosphere called the corona. This photo was made during the March 29, 2006 eclipse. Credit: Pedro Re

The weather is a factor in every eclipse. For this one, favored locations are eastern Oregon, Idaho and the Great Plains. Seeing the sun disappear from the sky for a few brief minutes is a deeply moving experience. You may recall eclipses where you’ve used a box to filter the sunlight — these were partial eclipses. You’ll never forget the experience of totality. Only then can you safely look in the direction of the sun and see it replaced by the black disk of the moon, rimmed with a garland of pink prominences and enveloped by the magnificent solar corona.

Times for Grand Island, NE located near the centerline:

Eclipse begins: 11:34 a.m. Central Daylight Times
Total eclipse begins: 12:59 p.m.
Eclipse ends: 2:26 p.m.

Everyone living under the big green “net” in this diagram will see at least a partial eclipse on Aug. 21. The narrow blue band locates the dark inner shadow (umbra) cast by the moon on Earth. Because the moon is constantly moving, the shadow moves over the land beneath it to trace a path. As long as you’re standing under that shadow, the sun will be completely covered in total eclipse. The fractions 0.20 to 0.80 show the percentage of the sun covered at maximum eclipse, so 0.20 is 20%, 0.40 is 40% and so on. For instance, in both Duluth, Minn. and Flagstaff, Ariz., the sun will be about 80% covered at maximum eclipse. Credit: F. Espenak, NASA’s GFSC

Because times vary for solar eclipses depending on your location within and without the central path, NASA has created a series of excellent, interactive Google Earth maps to help you out. Click on these links, zoom in to your city of choice, then click the city’s name to get the times for beginning, maximum and end of an eclipse. The times shown will be UT, so remember to subtract for your time zone as described earlier.

OK. Now that you know when and where the eclipses happen, mark the dates on your calendar and phone, so you don’t miss any of the excitement coming your way in the new year.

2 Responses

  1. “For viewers located along a narrow path that runs southeastward from Oregon through Idaho, Wyoming, Nebraska, Kansas, Missouri, Illinois, Kentucky, Tennessee and South Carolina, a total solar eclipse will be visible.”

    And don’t forget Georgia and North Carolina, too!

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