What to Know: Solar Eclipse 2017

Published: August 18, 2017

On August 21, 2017, the United States will be in the direct path of a total solar eclipse. In some parts of the United States, communities will be treated to the “path of totality” – a finite path of travel where the sun will reach total coverage from the Earth’s moon. The 2017 solar eclipse path of totality will be approximately 70 miles (115 kilometres) wide, and will travel west-to-east from Oregon to South Carolina.

Many notable US cities are inside or nearby the path of totality, including:

  • Salem, Oregon
  • Boise, Idaho
  • Casper, Wyoming
  • Lincoln, Nebraska
  • Kansas City, Missouri
  • Jefferson City, Missouri
  • Columbia, Missouri
  • St. Louis, Missouri
  • Carbondale, Illinois – point of longest total eclipse
  • Paducah, Kentucky
  • Clarksville, Tennessee
  • Nashville, Tennessee
  • Chattanooga, Tennessee
  • Columbia, South Carolina
  • Charleston, South Carolina

…and many other large cities.

The path of totality will also pass through parts of Georgia and Kansas.

How to Watch

LocationEstimated Time of TotalityApproximate Duration of Totality
Oregonbetween 10:15 am and 10:30 am PT2 mins. – 2 mins. 10 secs.
Idaho & eastern Oregonbetween 11:25 am and 11:55 am MT2 mins. 20 secs.
Wyoming & western Nebraskabetween 11:25 am and 11:55 am MT2 mins. 30 secs.
Nebraskabetween 12:50 pm and 1:30 pm CT2 mins. 35 secs.
northeast Kansasbetween 12:50 pm and 1:30 pm CT2 mins. 38 secs.
Missouribetween 12:50 pm and 1:30 pm CT2 mins. 40 secs.
southern Illinoisbetween 12:50 pm and 1:30 pm CT2 mins. 42 secs. (point of longest total eclipse)
western Kentucky & Nashville, Tennesseebetween 12:50 pm and 1:30 pm CT2 mins. 40 secs.
eastern Tennessee, northeast Georgia, & South Carolina between 2:25 pm and 2:50 pm ET2 mins. 35 secs.

*Note: Depending on geographical location, a gradual partial solar eclipse will be visible inside the path of totality for approximately 1 – 1 ½ hours before and after totality.

In its entirety, the moon will eclipse the sun for approximately three hours.

Not Part of the Path of Totality?

No problem! Your region will still be impacted by a partial solar eclipse. Find your area in the map below, along with its corresponding percent of coverage.

Notice: Parts of Mexico & Canada will also be able to observe a partial solar eclipse.

For precise calculations on when to expect the eclipse at your location, enter your City or ZIP Code into the 2017 Solar Eclipse Calculator.

A Historic Event

The Solar Eclipse of 2017 is especially historic because it is the first time an eclipse’s path of totality has exclusively traveled from coast-to-coast of the continental United States since June 8, 1918. In addition, it is the first eclipse that’s path of totality is visible solely in the United States since 1776.

The last time the US witnessed a total solar eclipse was February 26, 1979. In that instance, the path of totality merely brushed the United States, with it being visible only in the Pacific Northwest.

What is an Eclipse?

Whether it be of suns, moons, or planets, when three celestial bodies in a solar system form a straight-line configuration as a result of gravitational orbit, it is referred to as “syzygy.” What a mouthful! In case you are wondering, that word is pronounced “sciss-ih-gee” – like the start of the word “scissors.”

A solar eclipse occurs when the rotation of Earth’s moon aligns with that of the Earth and the sun, causing the moon to temporarily obstruct the sun’s light on Earth. As a result, the sky will temporarily darken at an uncharacteristic time of day, temperatures will temporarily fall, and bright stars will become visible. On a more humorous note, animals also react strangely during solar eclipses because they believe night time is falling.

Did You Know?

Umbra vs. Penumbra

Umbra versus penumbra? – What a conundrum!

As this illustration portrays, the path of totality is the route of the moon’s “umbra” – or, the point at which the moon completely obstructs the projection of solar light. At the moon’s outer edge, you will notice the “penumbra” – or, the projection of partial sunlight beyond the obstructing moon. The penumbra covers a much more vast geographical area, and is often referred to as a “partial solar eclipse.” So, not to worry – even if your location does not fall within an eclipse’s path of totality, it’s quite likely a partial solar eclipse can be seen in your neck of the woods.

Shadow Bands

Don’t forget! In the moments just before and just after the eclipse reaches totality, pay close attention to the ground to observe “shadow bands.” To know what you’re looking for, shadow bands look very similar to the reflective ripples in a swimming pool when the sun reflects off of the water.

In essence, shadow bands are serpentine rays of light that quickly dance across plain colored surfaces in the brief time when very limited and concentrated quantities of sunlight continue to project beyond the moon, moments before totality. Keep in mind that shadow bands do not appear in areas where partial eclipse reaches only 75 or 90 percent. Rather, shadow bands become visible only when sunlight merely becomes a narrow slit – say, 98 or 99 percent partial eclipse.

The science behind shadow bands is that as limited sunlight travels through Earth’s atmosphere, it is subjected to warm and cool cells in the umbra and penumbra, causing rays of light to bend before projecting on Earth’s surface. Because the moon continues to move into place, those serpentine rays of sunlight are also in continuous parallel motion.

Shadow bands are only visible for approximately 20-30 seconds prior to and in conclusion of totality. Even within the path of totality, depending on geographical viewpoint, shadow bands may or may not be present. For best shadow band projection, lay a large white bed sheet across the ground.

Is the Earth’s Moon a Perfect Circle?

A common misconception is that the moon casts a perfectly round shadow on the Earth’s surface during a solar eclipse. In reality, the moon’s shadow appears rounded but slightly rigid, depending on numerous variables – namely, the Earth’s elevation at a particular viewing point, or imperfections in the moon’s or Earth’s surfaces (ie: mountains or valleys). Because these are ever-changing variables, the moon’s shadow will appear differently to viewers across the country.

WARNING: If viewing the solar eclipse in the path of totality, it is safe to view the sun without safety glasses only when it has reached a complete eclipse. When viewing the sun prior to or in conclusion of a total or partial eclipse, it is necessary to wear appropriate safety eyewear. Failure to do so can cause serious eye damage, including partial loss of vision or blindness.