http://eclipse.gsfc.nasa.gov/SEgoogl...21Tgoogle.html


Introduction

This interactive Google map shows the path of the Total Solar Eclipse of 2017 Aug 21. The northern and southern path limits are blue and the central line is red. You MUST be somewhere within the central path (between the blue lines) to see the total phase of the eclipse. The eclipse is longest on the central line (red). The yellow lines crossing the path indicate the time and position of maximum eclipse at 10-minute intervals.
The green marker labeled GE is the point of Greatest Eclipse. The magenta marker labeled GD is the point of Greatest Duration. This is the location where the total eclipse lasts the longest along the entire path. (The magenta band on either side of the Greatest Duration marker shows a region where totality lasts within 0.1 seconds of the maximum.) In the case of the 2017 eclipse, the Greatest Duration is 2 minutes 40.2 seconds. This prediction does not take into account the mountains and valleys along the edge of the Moon. Detailed predictions using the Moon's limb profile show a corrected value of 2 minutes 41.7 seconds for Greatest Duration. For the sake of speed and simplicity, the effects of the lunar limb profile are NOT used in the predictions and map presented on this page.
Note that the central line of the eclipse (plotted in red) is banded by different colors for hundreds of miles east and west of the Greatest Duration marker. The colors correspond to the length of totality (duration of the total eclipse) along different sections of the central line:

  • Magenta - totality lasts within 0.1 second of Greatest Duration (over a span of ~160 miles or ~250 km)
  • Orange - totality lasts within 1 second of Greatest Duration (over a span of ~490 miles or ~790 km)
  • Green - totality lasts within 2 seconds of Greatest Duration (over a span of ~700 miles or ~1100 km)
  • Cyan - totality lasts within 5 seconds of Greatest Duration (over a span of ~1100 miles or ~1800 km)

You can be hundreds of miles from the theoretical point of Greatest Duration and still enjoy totality lasting within a fraction of a second of the maximum possible (as long as you stay within several miles of the central line). It's much more important to watch the weather forecasts a day or two before the eclipse and choose a location with the best chance of a cloud-free sky during the eclipse. Even in Oregon, the total eclipse still lasts 2 minutes. Good weather is the key to successful eclipse viewing - better to see a shorter eclipse from clear sky that a longer eclipse under clouds[1].
Important Note: The eclipse predictions in this interactive map DO NOT include the effects of mountains and valleys along the edge of the Moon. Such corrections for the lunar limb profile may change the contact times and eclipse durations by ~1-3 seconds. The exact location of Greatest Duration may also change by ~10-20 kilometers. A future version of this page will include the effects of the lunar limb profile.