Update Sunday May 20: Click here to watch the solar eclipse live online.
The astronomical orbits of several celestial bodies will coincide in some spectacular ways over the next few weeks in Northern California. First up this Sunday is the annular solar eclipse. But tempting though it may be, do not look at the sun without special equipment, as even viewing a small fraction can burn your retina.
What is it?
Don't mistake this for an annual event, otherwise you'll have to wait until 2023 to see the next one in Northern California.
Annular in this case means "ring," and viewers in Northern California can watch the moon pass in front of the sun Sunday afternoon, causing a "ring of fire" effect. In the Bay Area, the eclipse will begin at about 5:15 p.m. in the western sky, but will be most noticeable after 6 p.m. At approximately 6:33 p.m., you'll be able to see the moon cover about 90 percent of the sun for four minutes, before it continues past. The whole event will be over around 7:40 p.m.
During an annular eclipse the moon is at its furthest point from the Earth, or at its apogee, so that when viewed from the Earth the moon appears smaller than the sun. A total eclipse occurs when the sun and moon appear to be the same size, so that the moon completely blocks out the sun.
This is partly why annular eclipses are so rare, only occurring when the moon not only lines up with the sun and earth, but its orbit is just right and the moon is at its apogee.
Viewers in the Bay Area will be able to see the moon cover about 90 percent of the sun in the western part of the sky on Sunday evening. But for the full effect you'll have to drive several hours north closer to the California-Oregon border or out toward Reno. The NASA map below shows the eclipse's path. If you're anywhere between the blue lines, you'll see the full eclipse.
Plenty of places in the Bay Area are also holding special events to celebrate the eclipse. The Chabot Space and Science Center is holding a viewing party, but unfortunately it's sold out. Many National Parks are holding viewing parties, and Point Reyes National Seashore is holding a ranger-led talk and hike with special viewing equipment. The California Academy of Sciences is also holding a free viewing event with filtered telescopes and an astronomer on hand.
If you can't make it out for the event, never fear! You can watch it online.
Exact times vary slightly depending on where you're watching. The partial eclipse is viewable starting at 5:08 p.m. in Medford, Oregon. It will then "travel" southeast, hitting Reno, Nevada, for example, at 5:25 p.m.
The full eclipse will begin between 6:24 p.m. in Medford and also head southeast, lasting for about four minutes in each location. The partial eclipse will first end at 7:34 p.m. in Medford. You can find the specific times for your latitude and longitude at NASA by clicking on your location.
In the Bay Area, the eclipse will begin at about 5:15 p.m. in the western sky, but will be most noticeable after 6 p.m. At approximately 6:33 p.m., you'll be able to see the moon cover about 90 percent of the sun for four minutes, before continuing past. The whole event will be over around 7:40 p.m.
In the Bay Area the moon will move in front of the sun's lower right- hand corner and then continue diagonally until it passes over the sun's top left. The sky will dim as the moon covers the sun, which can create strange colors and startle animals, says Jonathan Braidman, an astronomer and instructor at the Chabot Space and Science Center.
"Occasionally people have reported strange colors in the sky during eclipses, in which you might see greens or blues that are a slightly different shade than you would normally see," Braidman told KQED's Amy Standen. "Because it does get slightly dimmer we have a chance to see some confused animals. There have been reports where because of the dimming of an eclipse like this, nocturnal animals will come out a bit earlier, or occasionally animals will go to bed a little earlier."
One of the the difficulties of watching a solar eclipse is that you can't look directly at it. Special solar eclipse viewers or welding glasses at a strength of 14 can protect your eyes. However, many online and local retailers are sold out of such devices.
"We're out, we're out of everything," said Sam Sweiss manager of Scope City in San Francisco's Fisherman's Wharf. "We've run out of solar filters, that's how many people want the mylar filters and the solar glass. The company [making it is] out of stock."
Luckily, it's pretty easy to construct your own solar eclipse viewer. You can simply poke a hole into a piece of paper or cardboard and then look at the projected image, said Chabot's Braidman. Or in a pinch, you can even put your hands together at a 90-degree angle and use the space in between your fingers to project an image onto the ground.
The Exploratorium has instructions on how to construct a simple pinhole projector.
You also need special filters to properly view an eclipse from a camera, binoculars or telescope. Just looking at the digital screen should be fine, said Braidman, but looking through the viewfinder is dangerous. Space.com, the New York Institute of Photography and Sky and Telescope all have good tips on how to properly photograph the eclipse.
This week's solar eclipse is only one of several astronomical experiences in store for us. There will be a lunar eclipse on June 4, and this century's last transit of Venus on June 5.
More on solar eclipses from NASA: