On Aug. 21, the day of the solar eclipse, Sacramento residents can expect a couple hours of respite from the full force of the sun as the moon moves to block about 80 percent of its rays.

Visible effects here will not be nearly as dramatic as they will be in the ‘path of totality’ -- the area where the total eclipse can be viewed.

However, “…At 80 percent, my feeling is that if didn’t know there were an eclipse and you were out, you’d still notice something," said Dr. Matthew Richter, a researcher in the University of California Davis Physics Department.

The sky will remain blue, he said, but it will be a little bit darker out, and the quality of the light will change.

“The light will be flatten in a way... there’ll be sharp definition – and you will definitely notice a different quality to the light, not just the amount,” said Richter.

The eclipse will begin at 9:03 a.m., when the moon begins to creep into the path of the sun, said Dr. Rodolfo Barniol Duran, an astrophysicist and assistant professor in the California State University Department of Physics and Astronomy.

At first, it will appear to be a tiny crescent biting into the sun, with the dark crescent slowly growing and rolling to one side over the next hour. It will reach the full 80 percent coverage by about 10:15 a.m., and then begin to slide off the other side.

During the eclipse, one of the most striking visual effects visible without any special eyewear or devices will be tiny crescents of light to be seen in the shadows of trees, said Richter, explaining that the small gaps between leaves act as pinhole cameras, projecting an image of the eclipse wherever the shadows fall.

By 11:40 a.m., the eclipse will be completed with sun and moon going their separate ways once again.

To see the total eclipse, at the closest spot, you would need to travel 382 miles northeast, according to Vox.com, which has this very cool graphic of what you will see. The ‘path of totality’ is a narrow band of about 70 miles, said Duran.

“We have some good viewing here in Sacramento,” said Duran.

Those who want to look at the sun are cautioned not to do so directly: either use specially made eclipse glasses, or make a pinhole camera or other indirect viewing device.

In its rotation around the earth, the moon passes between sun and every month, but because of a very slight tilt in its rotation, we don’t have an eclipse every month. Eclipses happen twice a year, and total eclipses only once every 18 months. Total eclipses over the US are even rarer.

The last one to pass over the United States was in 1979, Duran said.

“It is a very cool opportunity for us,” he said.