2017 Path of Totality
- Visualizations by:
- Ernie Wright
- View full credits
Movies
- totpath2017_720p30.mp4 (1280x720) [123.2 MB]
- totpath2017_720p30.webm (1280x720) [22.3 MB]
- totpath2017_1080p30.mp4 (1920x1080) [190.1 MB]
- totpath2017_360p30.mp4 (640x360) [40.4 MB]
- totpath2017_2160p30.mp4 (3840x2160) [407.4 MB]
Images
- usa.0500_print.jpg (1024x576) [257.5 KB]
- usa.0500_thm.png (80x40) [7.1 KB]
- usa.0500_searchweb.png (320x180) [108.8 KB]
Frames
- frames/1280x720_16x9_30p/usa/ (1280x720) [144.0 KB]
- frames/3840x2160_16x9_30p/ (3840x2160) [144.0 KB]
Presentations
- totpath2017_4515.key [125.2 MB]
- totpath2017_4515.pptx [124.7 MB]
This visualization closely follows the Moon's umbra shadow as it passes over the United States during the August 21, 2017 total solar eclipse. It covers the one hour and 40 minutes between 10:12 am PDT and 2:52 pm EDT. Through the use of a number of NASA datasets, notably the global elevation maps from Lunar Reconnaissance Orbiter, the shape and location of the shadow is depicted with unprecedented accuracy.
People traveling to see totality, likely numbering in the millions for this eclipse, will rely on maps that show the predicted location of this path. The math used to make eclipse maps was worked out by Friedrich Wilhelm Bessel and William Chauvenet in the 19th century, long before computers and the precise astronomical data gathered during the Space Age.
In keeping with their paper and pencil origins, traditional eclipse calculations pretend that all observers are at sea level and that the Moon is a smooth sphere centered on its center of mass. Reasonably accurate maps, including this one, are drawn based on those simplifying assumptions. Those who want greater accuracy are usually referred to elevation tables and plots of the lunar limb.
This animation shows the umbra and its path in a new way. Elevations on the Earth's surface and the irregular lunar limb (the silhouette edge of the Moon's disk) are both fully accounted for, and they both have dramatic and surprising effects on the shape of the umbra and the location of the path. To read more about these effects, go here.
The animation provides an overhead view of the umbra and runs at a rate of 30× real time — every minute of the eclipse takes two seconds in the animation. For an oblique view that emphasizes the terrain of the path, go here.
| Earth radius | 6378.137 km |
|---|---|
| Ellipsoid | WGS84 |
| Geoid | EGM96 |
| Moon radius | 1737.4 km |
| Sun radius | 696,000 km (959.645 arcsec at 1 AU) |
| Ephemeris | DE 421 |
| Earth orientation | earth_070425_370426_predict.bpc (ΔT corrected) |
| Delta UTC | 69.184 seconds (TT – TAI + 37 leap seconds) |
| ΔT | 68.917 seconds |
Movies
- eclipse_post_720p30.mp4 (1280x720) [18.4 MB]
- eclipse_post_720p30.webm (1280x720) [17.5 MB]
- eclipse_post_1080p30.mp4 (1920x1080) [34.3 MB]
- eclipse_post_360p30.mp4 (640x360) [7.0 MB]
Images
- eclipse_post.0001_print.jpg (1024x576) [92.6 KB]
Frames
- frames/1280x720_16x9_30p/atlantic/ (1280x720) [188.0 KB]
- frames/1920x1080_16x9_30p/atlantic/ (1920x1080) [188.0 KB]
This animation of the August, 2017 umbra path begins at 2:45 p.m. EDT, when the umbra is about to leave land and travel into the Atlantic Ocean, and it ends at 4:02 p.m. EDT as the umbra is about to leave the Earth's surface.
For More Information
Credits
Please give credit for this item to:
NASA's Scientific Visualization Studio
Visualizer
- Ernie Wright (USRA) [Lead]
Missions
This visualization is related to the following missions:Series
This visualization can be found in the following series:Datasets used in this visualization
Terra and Aqua BMNG (A.K.A. Blue Marble: Next Generation) (Collected with the MODIS sensor)
Credit: The Blue Marble data is courtesy of Reto Stockli (NASA/GSFC).
Dataset can be found at: http://earthobservatory.nasa.gov/Newsroom/BlueMarble/
See more visualizations using this data setSRTM DEM (Collected with the SIR-C sensor)
LRO DEM (A.K.A. Digital Elevation Map) (Collected with the LOLA sensor)
LRO/SELENE SLDEM2015 (A.K.A. DIgital Elevation Model) (Collected with the LOLA/TC sensor)
A digital elevation model of the Moon derived from the Lunar Orbiter Laser Altimeter and the SELENE Terrain Camera. See the description in Icarus. The data is here.
See more visualizations using this data setDE421 (A.K.A. JPL DE421)
Planetary ephemerides
Dataset can be found at: http://ssd.jpl.nasa.gov/?ephemerides#planets
See more visualizations using this data setNote: While we identify the data sets used in these visualizations, we do not store any further details nor the data sets themselves on our site.
Related pages

Are You Ready for the Eclipse? (Live Interviews on Aug. 16, 2017)
Aug. 5th, 2017
Read moreCanned interviews and b-roll will be available here starting Tuesday, August 15, at 6:00 p.m. ET. B-roll that goes along with 8.16.17 eclipse live shots. Canned interview with NASA Scientist, Dr. Nicholeen Viall. Canned interview with Dr Michelle Thaller/ NASA Scientist looking on camera. Each question is separated by a slate and there are two versions of each answer - one with graphics rolling during the SOT and one without graphics. TRT 9:52 Are you ready for the historic solar eclipse that’s just days away?Do you have what you need to see it safely?You can see the eclipse no matter where you are in North America on Aug. 21!August 21 will be a day for the history books. No matter where you are in North America, you’ll get to experience the first coast-to-coast solar eclipse in nearly a century! The dark shadow of the moon will sweep from Oregon to South Carolina, putting 14 states in the path of totality and providing a spectacular view of a partial eclipse across all 50 states.Eclipses are an incredible experience, but it’s important to view them safely. Join NASA scientists on Wednesday, August 16, from 6:00 a.m. – 12:30 p.m. ET and again from 3:00 p.m. – 8:00 p.m. ET to show your viewers what they need to safely see the eclipse whether they’re inside the path of totality or not. You should never look directly at the sun! The only safe way to look directly at the sun or partially eclipsed sun is through special-purpose solar filters, such as “eclipse glasses” or hand-held solar viewers. An eclipse is a striking phenomenon you won't want to miss, but you must carefully follow safety procedures.Solar eclipses happen somewhere in the world about every 18 months, but much of the time it happens over the ocean. To have an eclipse travel across so much land where millions of people live is incredibly rare, and makes for a unique opportunity for so many to witness one of nature’s most impressive shows. It’s also a great opportunity for scientists to see the sun’s faint outer atmosphere and evaluate how Earth responds to the sudden darkening.Take this opportunity to step outside and safely watch one of nature’s best shows!*** To book a window ***Contact Michelle Handleman michelle.z.handleman@nasa.gov / 301-286-0918HD Satellite Digital Coordinates for G17-K20/Up: Galaxy 17, Ku-band Xp 20, Slot Upper | 91.0 ° W Longitude | DL 12109.0 MHz | Vertical Polarity | QPSK/DVB-S | FEC 3/4 | SR 13.235 Mbps | DR 18.2954 MHz | HD 720p | Format MPEG2 | Chroma Level 4:2:0 | Audio EmbeddedSuggested Questions:1. The anticipated solar eclipse is just days away! What will we experience next week?2. We’ve been told never to look directly at the sun (even with sunglasses!). How can we enjoy this eclipse safely?3. For those in the path of totality – when is it safe to finally take off our solar glasses?4. We’re not in the path of totality – what interesting things should we lookout for?5. Why are you excited for this eclipse?6. Where can we learn more?Extra Questions for Longer Interviews:7. How did a picture of an eclipse in 1919 prove Einstein’s theory of relativity?8. Eclipses are actually a special type of transit. How are transits helping scientists search for life on other planets?9. Why does an eclipse only last for a few minutes?10. What happens to Earth during the eclipse?11. If you were looking back at Earth during the eclipse what would you see?12. How has our precise mapping of the moon helped us predict the path of eclipses?13. How long and where was the longest ever recorded eclipse?Location: NASA’s Goddard Space Flight Center/Greenbelt, MarylandInterviews With:Dr. Michelle Thaller / NASA ScientistDr. Alex Young / NASA ScientistDr. Jim Garvin / NASA ScientistDr. Nicholeen Viall / NASA ScientistDr. Eric Christian / NASA ScientistDr. Yari Collado-Vega / NASA Scientist [Spanish speaker]Dr. Geronimo Villanueva / NASA Scientist [Spanish speaker]https://eclipse2017.nasa.gov/@NASASunHow to photograph an eclipse.Planning to take photos of the eclipse? Check out our tips for capturing the best images:#Eclipse2017 Related pages

The Moon's Role in a Solar Eclipse
July 21st, 2017
Read moreThis video explains how our moon creates a solar eclipse, why it's such a rare event to see, and how data from NASA's Lunar Reconnaissance Orbiter has enhanced our ability to map an eclipse's path of totality.Music Provided by Universal Production Music: “Bring Me Up” – Anders Gunnar Kampe & Henrik Lars Wikstrom.Watch this video on the NASA.gov Video YouTube channel. While the sun is the main focus of a solar eclipse, our moon plays the most crucial role in creating this unique event. This video tutorial explains what happens during a total solar eclipse and a partial eclipse and how often they both occur. The video also explains how a solar eclipse differs from a lunar eclipse, and gives a helpful tip on how to remember the difference. In addition, the video examines how the two parts of the moon’s shadow, the umbra and penumbra, affect how we see an eclipse on the Earth, and illustrates the surprising true shape of the umbra. The video concludes by highlighting how data from NASA’s Lunar Reconnaissance Orbiter has helped us better map a solar eclipse’s path of totality. Visualizations included in this piece showcase the August 21, 2017 total solar eclipse happening in the United States. Related pages

Rare Total Solar Eclipse Is Only Two Months Away Live Shots 6.21.17
June 13th, 2017
Read moreB-roll for the live shots Canned interview with NASA Scientist Dr. Nicholeen Viall looking off camera. Soundbites are separated by slates. Includes transcript of soundbites. Canned interview in Spanish with Dr. Yari Collado-Vega. Soundbites are separated with slates Soundbites with Drs. Alex Young and Noah Petro. TRT 5:41. Includes full transcript with timecodes The Countdown is on for Rare Solar Eclipse Visible Across all of North AmericaFor the First Time in Nearly 100 Years, Millions of Americans Coast-to-Coast Will see an Eclipse Chat with NASA to find out how you can catch this spectacular eventOn August 21, 2017, daylight will fade to the level of a moonlit night as millions of Americans experience one of nature’s most awe-inspiring shows – a total solar eclipse. For the first time since 1918, the dark shadow of the moon will sweep coast-to-coast across the United States, putting 14 states in the path of totality and providing a spectacular view of a partial eclipse across all 50 states.NASA scientists are available Wednesday, June 21, from 6:00 a.m. – 12:00 p.m. ET to show your viewers the path of the eclipse, what they need to see it safely and talk about the unprecedented science that will be gathered from one of the most anticipated and widely observed celestial events in history. We’ll also give your viewers a sneak peek of a press conference about the eclipse NASA is having later that day.A solar eclipse happens when a rare alignment of the sun and moon casts a shadow on Earth. NASA knows the shape of the moon better than any other planetary body, and this data allows us to accurately predict the shape of the shadow as it falls on the face of Earth. While everyone in the U.S. will see the eclipse if their local skies are clear, people standing in the path of totality – completely in the moon’s shadow – will see stars and planets become visible in what is normally a sunlit sky. Eclipses provide an unprecedented opportunity for us to see the sun’s faint outer atmosphere in a way that cannot be replicated by current human-made instruments. Scientists believe this region of the sun is the main driver for the sun’s constant outpouring of radiation, known as the solar wind, as well as powerful bursts of solar material that can be harmful to our satellites, orbiting astronauts and power grids on the ground. HD Satellite Coordinates for G17-K18/LO: Galaxy 17 Ku-band Xp 18 Slot Lower | 91.0 ° W Longitude | DL 12051.0 MHz | Vertical Polarity | QPSK/DVB-S | FEC 3/4 | SR 13.235 Mbps | DR 18.2954 MHz | HD 720p | Format MPEG2 | Chroma Level 4:2:0 | Audio Embedded**To book a window contact** / Michelle Handleman / michelle.z.handleman@nasa.gov / 301-286-0918Suggested Questions:1. This is the first time in nearly 100 years that the United States will have the opportunity to see a total solar eclipse coast-to-coast! What will happen on August 21?2. This eclipse will be the most widely observed and shared celestial event in U.S. history. Why are scientists excited for this eclipse?3. Eclipses allow scientists to see the sun’s faint outer atmosphere, which is actually hotter than its surface. What can you tell us about NASA’s upcoming mission that will touch the sun?4. How does NASA’s study of our sun help us explore the solar system?5. How does NASA’s mapping of the moon give us the accurate path of totality?6. Where can we learn more?Live Shot Details:Location: NASA’s Goddard Space Flight Center/Greenbelt, MarylandScientists:Dr. Alex Young / NASA ScientistDr. Nicholeen Viall / NASA ScientistDr. Noah Petro / NASA ScientistDr. Geronimo Villanueva [in Spanish] / NASA ScientistTo learn more visit:Eclipse Across AmericaOn Twitter @NASASun For More InformationSee [https://eclipse2017.nasa.gov/](https://eclipse2017.nasa.gov/) Related pages

2017 Eclipse State Maps
Feb. 5th, 2017
Read moreOregon Montana Idaho Wyoming Nebraska Iowa Kansas Missouri Illinois Kentucky Tennessee Georgia North Carolina South Carolina The path of totality passes through 14 states during the total solar eclipse on August 21, 2017. A map of each of these states, created for NASA's official eclipse 2017 website, is presented here. Except for Montana, each map is 8 inches wide (or high) at 300 DPI. The umbra is shown at 3-minute intervals, with times in the local time zone at the umbra center. The duration of totality is outlined in 30-second increments. Interstate highways are blue, other major roads are red, and secondary roads are gray.Some sources list only 12 states for this eclipse, but in fact the path of totality also grazes the southwestern borders of both Montana and Iowa. The Montana part of the path is in a roadless area at the southern end of the Beaverhead Mountains, a range that defines sections of both the Montana-Idaho border and the Continental Divide. The Iowa part of the path is west of Interstate 29 near Hamburg, south of 310 Street, and bounded on the west by the Missouri River. It includes the Lower Hamburg Bend Wildlife Management Area. For More InformationSee [http://eclipse2017.nasa.gov](http://eclipse2017.nasa.gov) Related pages

2017 Path of Totality: Oblique View
Dec. 12th, 2016
Read moreThis animation closely follows the Moon's umbra shadow as it passes over the United States during the August 21, 2017 total solar eclipse. Through the use of a number of NASA datasets, notably the global elevation maps from Lunar Reconnaissance Orbiter, the shape and location of the shadow is depicted with unprecedented accuracy. During the August 21, 2017 total solar eclipse, the Moon's umbral shadow will fly across the United States, from Oregon to South Carolina, in a little over 90 minutes. The path of this shadow, the path of totality, is where observers will see the Moon completely cover the Sun for about two and a half minutes.People traveling to see totality, likely numbering in the millions for this eclipse, will rely on maps that show the predicted location of this path. The math used to make eclipse maps was worked out by Friedrich Wilhelm Bessel and William Chauvenet in the 19th century, long before computers and the precise astronomical data gathered during the Space Age.In keeping with their paper and pencil origins, traditional eclipse calculations pretend that all observers are at sea level and that the Moon is a smooth sphere centered on its center of mass. Reasonably accurate maps, including this one, are drawn based on those simplifying assumptions. Those who want greater accuracy are usually referred to elevation tables and plots of the lunar limb.This animation shows the umbra and its path in a new way. Elevations on the Earth's surface and the irregular lunar limb (the silhouette edge of the Moon's disk) are both fully accounted for, and they both have dramatic and surprising effects on the shape of the umbra and the location of the path. To read more about these effects, go here.The animation runs at a rate of 30× real time — every minute of the eclipse takes two seconds in the animation. The oblique view emphasizes the terrain of the umbral path. For an overhead view, go here.Earth radius6378.137 kmEllipsoidWGS84GeoidEGM96Moon radius1737.4 kmSun radius696,000 km (959.645 arcsec at 1 AU)EphemerisDE 421Earth orientationearth_070425_370426_predict.bpc (ΔT corrected)Delta UTC69.184 seconds (TT – TAI + 37 leap seconds)ΔT68.917 seconds For More InformationSee [http://eclipse2017.nasa.gov](http://eclipse2017.nasa.gov) Related pages

Umbra Shapes
Dec. 12th, 2016
Read moreThis animation shows the shape of the Moon's umbral shadow during the August 21, 2017 total solar eclipse, calculated at three different levels of detail. The dark gray is the closest to the true shape. Mountains and valleys near the south pole of the Moon are visible in this image of a partial solar eclipse taken from space by the Solar Dynamics Observatory spacecraft on October 7, 2010. The lunar limb as it changes during the two-month period centered on the 2017 eclipse. Orange lines mark the equator and meridian. The blue outline is the limb, exaggerated by a factor of 18. Higher elevations can lift the observer into or out of the shadow cone. For centuries, eclipse maps have depicted the shape of the Moon's umbra on the ground as a smooth ellipse. But as this visualization shows — in a way never seen before — the shape is dramatically altered by both the rugged lunar terrain and the elevations of observers on the Earth.The lunar umbra is the part of the Moon's shadow where the entire Sun is blocked by the Moon. In space, it's a cone extending some 400,000 kilometers behind the Moon. When the small end of this cone hits the Earth, we experience a total solar eclipse. The umbra shape discussed here is the intersection of the umbra cone with the surface of the Earth. On an eclipse map, this tells you where to stand in order to experience totality.The true shape of the umbra is more like an irregular polygon with slightly curved edges. Each edge corresponds to a single valley on the lunar limb, the last (or first) spot on the limb that lets sunlight through. This is the location of the diamond part of the diamond ring effect visible in the seconds just before or just after totality. An observer standing at the cusp where two edges meet will be treated to a double diamond ring.As these edges pass over mountain ranges (for the 2017 eclipse, the Cascades, Rockies, and Appalachians), they are scalloped by the peaks and valleys of the landscape. The higher elevations in the western states in 2017 also shift the umbra toward the southeast (in the direction of the Sun's azimuth) by as much as 3 kilometers.In the animation, the red ellipse is the shape that results from assuming that the Moon and the Earth are both smooth. This is the shape most commonly seen on eclipse maps. The white shape shows the effect of the mountains and valleys along the silhouette edge of the Moon (the lunar limb). The dark gray shape adds the effect of elevations on the Earth's surface.Details The math used currently to predict and map eclipses was first described by Friedrich Wilhelm Bessel in 1829 and was expressed in its modern form by William Chauvenet in 1863. Bessel's method uses a coordinate system based on a plane, called the fundamental plane, passing through the center of the Earth and perpendicular to the Sun-Moon line. This greatly simplifies the calculations. The intersection of the Moon's shadow with the plane is always a circle, for example, and its size depends only on the Moon's z-coordinate.Using this coordinate system, it's possible to calculate just a handful of numbers, called Besselian elements, that can be plugged into various equations to predict almost anything you'd want to know about an eclipse. This was especially important in the 19th and early 20th centuries, when the math had to be done by hand. Even now, the simplicity of this approach allows us to compare hundreds or even thousands of eclipses far into the past and the future, using a reasonable amount of computer time. Bessel's method for predicting eclipses pretends that the Moon is a smooth sphere, when in fact its terrain is more rugged and extreme than the Earth's. The valleys along the silhouette edge, or limb, of the Moon affect the timing and duration of an eclipse by allowing sunlight to sneak through in places where a smooth Moon would block it. Eclipse calculations can correct for this by using a limb profile, a description of the surface elevations around the disk of the Moon.Until quite recently, everyone used the limb profiles published in 1963 by Chester Burleigh Watts. To produce his profiles, Watts designed a machine that traced some 700 photographs of the Moon covering the full range of angles, or librations, visible from Earth, an effort that spanned 17 years. Eclipse calculations are now moving to much more accurate limb profiles based on data from NASA's Lunar Reconnaissance Orbiter (LRO) and the Japan Space Agency's Kaguya spacecraft. The lunar limb in the present work is based on LRO laser altimetry and on a hybrid LRO/Kaguya dataset called SLDEM2015. To create a limb profile, each point in an elevation map is transformed into 3D cartesian coordinates in a Moon body-fixed frame. At each time step in the eclipse calculation, the point cloud is rotated into fundamental plane coordinates. The limb profile then comprises the set of points lying farthest from the shadow axis. The animation above shows how this profile changes as the Moon librates.Observer elevations are taken from SRTM, a digital elevation map of the Earth based on radar data collected during the February, 2000 flight of the Space Shuttle Endeavor. As illustrated by the following cartoon, higher elevations can lift the observer either into or out of the umbra cone. The overall effect is to shift the umbra toward the Sun. For More InformationSee [http://eclipse2017.nasa.gov](http://eclipse2017.nasa.gov) Related pages

2017 Total Solar Eclipse Map and Shapefiles
Dec. 12th, 2016
Read moreA map of the United States showing the path of totality for the August 21, 2017 total solar eclipse. This is version 2 of the map, available at both 5400 × 2700 and 10,800 × 5400. A global map of the path of totality for the August 21, 2017 total solar eclipse. A map of the United States showing the path of totality for the August 21, 2017 total solar eclipse. The shapes of the umbra and penumbra, provided in ESRI shapefile format suitable for use in GIS software. The umbra, path, and center line in shapefile format for use in GIS software. This shapefile set is intended for larger scale (higher resolution) mapping. The preview image shows the umbra at 90-second intervals as it passes through Nebraska. Map of the 1918 total solar eclipse, from the American Ephemeris and Nautical Almanac for the Year 1918. This is a scan from the copy of the almanac held by the NASA Goddard library. Map of the 1979 total solar eclipse, from the American Ephemeris and Nautical Almanac. This is a scan from Ernie Wright's personal copy of U.S. Naval Observatory Circular No. 157. This map of the United States shows the path of the Moon's umbral shadow — the path of totality — during the total solar eclipse on August 21, 2017, as well as the obscuration (the fraction of the Sun's area covered by the Moon) in places outside the umbral path. Features include state boundaries, major highways, and 833 place names. At 18" × 9" (45 × 22.5 cm), the scale of the map is approximately 1:10,000,000.The umbra is shown at 10-minute intervals. Umbra shapes within U.S. time zones are labeled in local time. To read about the reason the shapes aren't smooth ovals, go here.The map uses a number of NASA data products. The land color is based on Blue Marble Next Generation, a global mosaic of MODIS images assembled by NASA's Earth Observatory. Elevations are from SRTM, a radar instrument flown on Space Shuttle Endeavour during the STS-99 mission. Lunar topography, used for precise shadow calculations, is from NASA LRO laser altimetry and JAXA Kaguya stereo imaging. Planetary positions are from the JPL DE421 ephemeris. The lunar limb profile and eclipse calculations are by the visualizer. ShapefilesThe map was rendered in animation software, but maps are more typically created using GIS tools and vector datasets. A set of shapefiles describing the umbra and penumbra extents is provided below in two Zip archives, one for global, U.S., and statewide maps and the other for county and city scale mapping. eclipse2017_shapefiles.zip contains the following nine shapefiles:penum17 contains the contours for maximum obscuration at 90%, 75%, 50%, 25% and the penumbra edge at 0%.penum17_1m contains a time sequence of penumbra outlines at 1-minute intervals from 17:00 to 19:15 UTC, for 95% to 75% obscuration in 5% steps.upath17 and w_upath17 contain the path of totality. The w_ version is the complete (world) path, at somewhat reduced resolution, while the other is a high-resolution version of the path limited to the 96 degrees of longitude centered on the U.S.umbra17 and w_umbra17 contain umbra shapes spaced at 10-minute intervals, again at U.S. and world (w_) scales.w_umbra17_1m contains umbra shapes at 1-minute intervals from 16:49 to 20:02 UTC, covering the complete timespan of totality.center17 and w_center17 contain the center line.The projection for all of these shapefiles is WGS84, latitude-longitude, in degrees. A minimal .PRJ file reflecting this projection is included for each shape. eclipse2017_shapefiles_1s.zip is intended for larger-scale (higher resolution) mapping. It contains the following shapefiles:umbra17_1s contains 6000 umbra shapes at one-second intervals from 17:12 to 18:52 UTC. These are high-resolution shapes with roughly 100-meter precision. The attributes for each shape include both a string representation of the UTC time and an integer containing the number of seconds past midnight of eclipse day.upath17_1s contains the path of totality, limited to the extent of the 6000 umbra shapes, roughly the 54 degrees of longitude between 130°W and 76°W. The shape was calculated at a precision of 250 meters.ucenter17_1s contains the center line as a polyline with points at one-second intervals.durations17_1s contains shapefiles for duration of totality at 30-second intervals. As with the path, these shapes are truncated and invalid at the ends.Past Eclipses The last time a total solar eclipse spanned the contiguous United States was in 1918. The path of totality entered the U.S. through the southwest corner of Washington state and passed over Denver, Jackson (Mississippi) and Orlando before exiting the country at the Atlantic coast of Florida. Prior to 2017, the most recent total solar eclipse in the Lower 48 was in 1979. Totality was visible in Washington, Oregon, Idaho, Montana, and North Dakota, as well as parts of Canada and Greenland. The author saw this eclipse in Winnipeg, Manitoba. For More InformationSee [http://eclipse2017.nasa.gov](http://eclipse2017.nasa.gov) Related pages

2017 Total Solar Eclipse in the U.S.
Sept. 9th, 2015
Read moreA view of the United States during the total solar eclipse of August 21, 2017, showing the umbra (black oval), penumbra (concentric shaded ovals), and path of totality (red) through or very near several major cities. A view of the United States during the total solar eclipse of August 21, 2017, showing the umbra (black oval), penumbra (concentric shaded ovals), and path of totality (red). This version omits the city and state names and the statistics display. A view of the United States during the total solar eclipse of August 21, 2017, showing the umbra (black oval), penumbra (concentric shaded ovals), and path of totality (red). This version includes images of the Sun showing its appearance in a number of locations, each oriented to the local horizon. On Monday, August 21, 2017, the Moon will pass in front of the Sun, casting its shadow across all of North America. This will be the first total solar eclipse visible in the contiguous United States in 38 years.The Moon's shadow can be divided into areas called the umbra and the penumbra. Within the penumbra, the Sun is only partially blocked, and observers experience a partial eclipse. The much smaller umbra lies at the very center of the shadow cone, and anyone there sees the Moon entirely cover the Sun in a total solar eclipse.In the animation, the umbra is the small black oval. The red streak behind this oval is the path of totality. Anyone within this path will see a total eclipse when the umbra passes over them. The much larger shaded bullseye pattern represents the penumbra. Steps in the shading denote different percentages of Sun coverage (eclipse magnitude), at levels of 90%, 75%, 50% and 25%. The yellow and orange contours map the path of the penumbra. The outermost yellow contour is the edge of the penumbra path. Outside this limit, no part of the Sun is covered by the Moon.The numbers in the lower left corner give the latitude and longitude of the center of the umbra as it moves eastward, along with the altitude of the Sun above the horizon at that point. Also shown is the duration of totality: for anyone standing at the center point, this is how long the total solar eclipse will last. Note that the duration varies from just 2 minutes on the West Coast to 2 minutes 40 seconds east of the Mississippi River.About AccuracyYou might think that calculating the circumstances of an eclipse would be, if not easy, then at least precise. If you do the math correctly, you’d expect to get exactly the same answers as everyone else. But the universe is more subtle than that. The Earth is neither smooth nor perfectly spherical, nor does it rotate at a perfectly constant, predictable speed. The Moon isn’t smooth, either, which means that the shadow it casts isn’t a simple circle. And our knowledge of the size of the Sun is uncertain by a factor of about 0.2%, enough to affect the duration of totality by several seconds.Everyone who performs these calculations will make certain choices to simplify the math or to precisely define an imperfectly known number. The choices often depend on the goals and the computing resources of the calculator, and as you'd expect, the results will differ slightly. You can get quite good results with a relatively simple approach, but it sometimes takes an enormous effort to get only slightly better answers.The following table lists some of the constants and data used for this animation.Earth radius6378.137 kmEarth flattening1 / 298.257 (the WGS 84 ellipsoid)Moon radius1737.4 km (k = 0.2723993)Sun radius696,000 km (959.634 arcsec at 1 AU)EphemerisDE 421Earth orientationearth_070425_370426_predict.bpc (ΔT corrected)Delta UTC68.184 seconds (TT – TAI + 36 leap seconds)A number of sources explain Bessel’s method of solar eclipse calculation, including chapter 9 of Astronomy on the Personal Computer by Oliver Montenbruck and Thomas Pflager and the eclipses chapter of The Explanatory Supplement to the Astronomical Almanac. The method was adapted to the routines available in NAIF's SPICE software library.The value for the radius of the Moon is slightly larger than the one used by Fred Espenak and slightly smaller than the one used by the Astronomical Almanac. The Sun radius is the one used most often, but see figure 1 in M. Emilio et al., Measuring the Solar Radius from Space during the 2003 and 2006 Mercury Transits for a sense of the uncertainty in this number.Both the elevations of locations on the Earth and the irregular limb of the Moon were ignored. The resulting small errors mostly affect the totality duration calculation, but they tend to cancel out—elevations above sea level slightly lengthen totality, while valleys along the lunar limb slightly shorten it. The effect on the rendered images is negligible (smaller than a pixel).Another minor complication that's ignored here is the difference between the Moon's center of mass (the position reported in the ephemeris) and its center of figure (the center of the disk as seen from Earth). These two centers don't exactly coincide because the Moon's mass isn't distributed evenly, but the difference is quite small, about 0.5 kilometers. Related pages

Untitled
June 12th, 2017
Read moreSee the most accurate map for Aug 21, 2017's total solar eclipse. Data visualizer Ernie Wright explains how he put together a more accurate eclipse path. The path of totality across the United States. The jagged profile of the moon as measured by NASA's Lunar Reconnaissance Orbiter. An illustration of the Lunar Reconnaissance Orbiter at the moon. Related pages

Tracing the 2017 Solar Eclipse
Dec. 14th, 2016
Read moreHear data visualizer Ernie Wright discuss the map in the video above. To see the maps unedited, watch the two videos below.Music credit: Life Choices by Eric ChevalierComplete transcript available.Watch this video on the NASA Goddard YouTube channel. This animation closely follows the Moon's umbra shadow as it passes over the United States during the August 21, 2017 total solar eclipse. Through the use of a number of NASA datasets, notably the global elevation maps from Lunar Reconnaissance Orbiter, the shape and location of the shadow is depicted with unprecedented accuracy. When depicting an eclipse path, data visualizers have usually chosen to represent the moon's shadow as an oval. By bringing in a variety of NASA data sets, visualizer Ernie Wright has created a new and more accurate representation of the eclipse. For the first time, we are able to see that the moon's shadow is better represented as a polygon. This more complicated shape is based NASA's Lunar Reconnaissance Orbiter's view of the mountains and valleys that form the moon's jagged edge. By combining moon's terrain, heights of land forms on Earth, and the angle of the sun, Wright is able to show the eclipse path with the greatest accuracy to date. The 2017 Path of Totality Read more about this map The 2017 Path of Totality: Oblique View Read more about this map Related pages