The 2017 Total Solar Eclipse Will Be Historic — Here’s Why

Solar Eclipses weren’t always seen on Earth

For a solar eclipse to be visible from earth, the sun, the moon and the earth must line up in a fairly precise arrangement in 3-D space. For a long period of the earth’s history, the moon wasn’t aligned with the earth to make a solar eclipse visible but the lunar orbit changes at a rate of about 2 cm every year and now you can see solar eclipses. In about 600 million years, the moon’s orbit will have changed enough that the eclipse will no longer be visible from the earth.