The day of the Great American Eclipse is finally here.  

Just over an hour before 11:33 a.m. MDT, the Salt Lake Valley sky will start to transition from a typical late-morning hue to dusk as the moon makes it way across the sun, gradually blotting out sunlight.

Monday’s eclipse is the first in 99 years to traverse the U.S. coast to coast, with the path of totality stretching from Salem, Oregon, through nearby Idaho and Wyoming, and then south and eastward across the rest of the country. A partial eclipse will be visible on most of the North American continent.

Build up for the once-in-a-generation astronomical event has been months in the making. Residents across the Beehive State have scrambled to make travel plans northward into the path of totality, buy safe protective eyewear and make arrangements for their school-aged children — some of whom will also be starting their 2017-2018 school year.

For residents planning to watch the eclipse, here is what you need to know:

Eclipse 101

A solar eclipse occurs when the moon travels between the sun and the Earth, blocking all or part of the sun’s rays, according to the National Aeronautics and Space Administration. It’ll take about three hours for the moon to pass from one edge of the sun to the other.

In northern Utah, the eclipse will begin about 10:14 a.m. Monday, reach its peak at 11:33 a.m. and end just before 1 p.m. 

Totality — when the moon fully blocks the sun — will last about 2 minutes and 40 seconds. But in Utah, only 91 percent of the sun will be covered by the moon during the eclipse.

Seth Jarvis, director of the Clark Planetarium, said the sky will dim as it does at sunset and shadows will be darker and more crisp than usual. Some planets might be even be visible in Utah, he added.

The closest locations along the path of totality closest to Utah are a few hours north in Idaho and Wyoming.

Eclipse weather

Eclipse viewing could be spotty for northern Utahns. The National Weather Service forecast partly cloudy skies in the Salt Lake and Tooele valleys Monday, as well as for areas further north.

Temperatures are expected to range in the upper-80s and low 90s Monday. The path of the total eclipse will pass through central and southeastern Idaho and then through Wyoming, where partly cloudy skies and highs in the mid-80s were expected by early afternoon.

Cardboard frames for solar eclipse glasses are stacked in the American Paper Optics factory in Bartlett, Tenn., on Wednesday, June 21, 2017. The company is one of many businesses _ hotels, campgrounds and stores _ taking advantage of the total solar eclipse _ when the moon passes between Earth and the sun. The moon’s shadow will fall in a diagonal ribbon across the U.S., from Oregon to South Carolina. (AP Photo/Adrian Sainz)

Watching the eclipse safely

If you are watching the eclipse in Utah — or anywhere else for that matter — there is no point at which you can safely view it directly without protective eyewear.

Looking at the sun anytime — during an eclipse or not — risks long-term or permanent damage to the retina’s macula, an oval shaped area at the center of the retina that controls high-resolution and color vision. The damage, which isn't always immediately painful, manifests as blurred or blind spots in the center of vision, making it difficult to read or distinguish facial features.

“The truth is, we really don’t know exactly how quickly damage can happen,” said Jeff Pettey, ophthalmologist at the John A. Moran Eye Center. “The safest advice is don’t look directly at the sun or the eclipse.”

But there are several ways to watch the eclipse safely. Residents across the country have snapped up protecting eclipse glasses — some of which later proved to be faulty, forcing online retailer Amazon.com to issue a recall. Demand also has been high for shade 14 welder’s glass, which also shields against damaging rays.

The Clark Planetarium sold all of its 121,000 pairs of eclipse glasses last week, as many Utahns scrambled to replace glasses after Amazon’s recall.  

If you are concerned your eclipse glasses aren’t safe, check if the following companies appear on your glasses with their contact information. Jarvis said the following suppliers have been verified by an accredited testing lab to meet the ISO 12312-2 international safety standards:

  • American Paper Optics (Eclipser)
  • Celestron (EclipSmart Glasses & Viewers)
  • DayStar (Solar Glasses)
  • Explore Scientific (Solar Eclipse Sun Catcher Glasses)
  • Halo Solar Eclipse Spectacles
  • Lunt Solar Systems (SUNsafe SUNglasses)
  • Meade Instruments (EclipseView Glasses & Viewers)
  • Rainbow Symphony (Eclipse Shades)
  • Seymour Solar (Helios Glasses)
  • Thousand Oaks Optical (Silver-Black Polymer & SolarLite)

Residents also can view the eclipse indirectly with homemade pinhole cameras and projectors. There also are solar filters for telescopes, binoculars and cameras.

Where to watch 

Branches of the Salt Lake County Library will host free events with activities for the whole family. Clark Planetarium volunteers also will hold events at The Gateway Plaza Fountains in downtown Salt Lake City and Wheeler Farm in Murray. 

Here are specifics on select viewing events:

Clark Planetarium

Volunteers from the planetarium and Goldman Sachs will host free events at three locations, with solar telescopes and pinhole viewers available for free; eclipse viewers will be available for $2 each. Note the main library event is limited to 200 attendees.

Where • The Gateway Plaza Fountains (400 West and South Temple), Wheeler Farm (6351 S. 900 East, Murray), Salt Lake City Public Library main branch (210 E. 400 South)

When • 9:30 a.m. to 1:30 p.m.
Salt Lake County Library locations

Story time, crafts, rocket launching, solar eclipse displays and more at these free events.

Bingham Creek • 10 a.m., 4834 W. 9000 South, West Jordan

Herriman • 10 a.m., 5380 W. Main St.

Holladay • 11 a.m., 2150 E. Murray-Holladay Road (4730 South)

Magna • 10 a.m., 2675 S. 8950 West

Millcreek • 10 a.m., 2266 E. Evergreen Ave.

Riverton • 10:15 a.m., 12877 S. 1830 West

Sandy • 10 a.m., 10100 S. Petunia Way (1405 East)

South Jordan • 10 a.m., 10673 S. Redwood Road

Taylorsville • 10:30 a.m., 4870 S. 2700 West

West Jordan • 10 a.m., 8030 S. 1825 West

Whitmore • 10:15 a.m., 2197 E. Fort Union Blvd.
University of Utah J. Willard Marriot Library

Free solar eclipse viewers, Sunchips and Capri Sun drinks as well as free giveaways throughout the viewing.

Where • Library Plaza, 295 S. 1500 East, Salt Lake City

When • 10 a.m. to noon

For some students, school year kicks off with solar eclipse

School is back in session for districts across the state — including the Granite, Salt Lake and Murray school districts in Salt Lake County — and many are planning to use the solar eclipse as a learning opportunity for students.

Granite School District spent roughly $30,000 to provide protective eyewear to each of its 68,000 students, spokesman Ben Horsley said. Some schools within Salt Lake City School District and Murray School District also planned viewing events as part of their first-day-of-school schedules, while others are opting to keep students indoors as a safety precaution.

“It’s a good thing to have this coincide with the first day of school,” Salt Lake School District spokeswoman Yandary Zavala Chatwin said. “We think it will create memorable experiences for the students in the district.”

If you’re traveling, prepare for delays

Travelers from across the country and world will be descending on different points along the eclipse’s path of totality, which includes several Utah-accessible locations in Idaho and Wyoming.

Idaho and Utah transportation officials are expecting significant delays along the I-15 corridor in the hours following the eclipse, based on predictions that many eclipse-goers will be head home shortly after the event ends. Construction projects along the interstate in both states have been halted or adjusted to alleviate preventable congestion.

Authorities also are urging residents to be prepared for the travel delays. Vince Trimboli, spokesman for the Idaho Transportation Department, said travelers should pack extra food and water and ensure their gas tanks are full before hitting the road.