What will happen on solar eclipse day, hours and minutes before totality |

On Monday, a total solar eclipse will sweep from Mexico to Maine, plunging rural farmland and major cities alike into a sudden daytime darkness. The sun’s atmosphere will fan outward from behind a jet-black moon in a spectacle the majority of the Lower 48 won’t witness again until the year 2045.

NASA is estimating that 32 million Americans will be in the path of totality, which sweeps over San Antonio, Dallas, Little Rock, Indianapolis, Cleveland, Buffalo and Burlington, Vt. It comes less than seven years after a more fleeting total eclipse made a path from the Oregon coastline to South Carolina on Aug. 21, 2017.

This eclipse will be the longest-lasting of any on land since at least 2009, and arguably the most widely observed in history. What’s more, it comes at a time of peak magnetic chaos on the sun, which should make for a more striking show during totality, assuming you have clear skies.

Here we break down what you’ll see in the hours, minutes and seconds leading up to totality.

Start of partial eclipse

Scientists refer to “first contact” as the moment that the moon nicks the solar disk — or when the partial phase of the eclipse begins. For those along the path of totality, this will be about one to two hours before totality.

Within a minute or two of first contact, you’ll see the moon begin to encroach on the right side of the sun. The only way you’ll notice that will be with eclipse glasses. Be sure to look up when the partial eclipse begins at your location; note that the partial eclipse will be viewable over the entire Lower 48 states, even if only those along the roughly 115-mile-wide path from Texas to Maine will see a total eclipse.

60 to 15 minutes to totality

Unless you have eclipse glasses on, you won’t notice much at first. But over the next 45 minutes, you’ll be able to see the moon’s blockage of the sun grow. First it’ll be a nibble. Then a bite. Then only a crescent will remain.

15 minutes to totality

About 15 minutes from totality, changes in your surroundings will become more noticeable. Seventy to 80 percent of the sun will be obscured, and the landscape will look less illuminated. It might resemble an old western-style movie, akin to a sepia filter on your phone. The color might seem off a bit, as if the sun is shining through a smoky pane of glass. You may feel a general sense of unease or foreboding.

Temperatures will begin dropping. You may also see most of the white, puffy cumulus clouds fizzling because of the loss of heat from the sun.

10 minutes to totality

You may first begin to think to yourself, “I need a vest” or “it’s getting cool.” As totality approaches, temperatures could drop by as much as 10 to 12 degrees if the air is dry and crisp, or 5 to 8 degrees if it’s humid.

Around the same time, the shadows will be getting visibly sharper. During a solar eclipse, the sun’s apparent size shrinks, meaning shadows are cast from a smaller source. As a result, shadows sharpen, because the rays of light — and therefore shadows — overlap more.

You might also notice small sickle-shaped projections of the mostly eclipsed sun in the shadows of leaves and trees; each small gap or opening acts as a miniature “pinhole projector.”

Around this time, it will start to feel weird outside. The sun will look like it’s shining high in the sky — and indeed it is — but with only 20 percent of its usual intensity. Crickets will start chirping. Birds may return to their roosts.

90 seconds before totality

With a minute and a half left to go, things will start happening fast — and the ambient environment will transform before your eyes. There are a number of things to look out for:

Shadow bands

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The moon will be nearly covering the whole sun, and the sun will appear to shrink to a point source of light. This means that the last rays of sunlight we get are fully parallel and aligned, or collimated.

However, atmospheric turbulence (air pockets, differences in temperature, etc.) will bend, or refract, parallel rays at slightly different angles. The now-misaligned rays will create a bizarre interference pattern on the ground. It will be reminiscent of the shadowy wavelets that ripple on the floor of swimming pools. If you have a white towel, sheet or piece of poster board, bring that and place it on the ground. It will make observing the shadow bands easier.

Shadow bands first appear about 90 seconds before totality, and are most noticeable between 60 seconds and 30 seconds before totality. They also can be seen in the moments after totality.

Look to the southwest about 90 seconds before totality. The sky will look purple or dusky, as if a veil of darkness is being draped overhead. The rest of the sky will look normal.

You’ll be seeing the edge of the umbra — the darkest part of the moon’s shadow — arriving at several times the speed of sound. When the shadow crosses into Texas from Mexico, it’ll be moving at 1,600 mph. By the time it gets to northern Maine some 68 minutes later, it’ll move at a whopping 3,000 mph.

45 seconds to totality

The sky will abruptly darken faster than you can possibly imagine. Each time you blink, you’ll open your eyes to a different landscape. Your eyes might struggle to adjust at first. Stars will awaken from their midday slumber, suddenly becoming noticeable and twinkling overhead. Jupiter will also emerge above and to the left of the sun; Venus, and perhaps Saturn and Mars, will make an appearance below to the right.

Eventually, the sky will plunge into a deep shade of royal blue that you may not have seen before. It’s difficult to describe. Winds will slacken or abate as the air, rapidly chilled by the moon’s shadow, sinks — suppressing any breeze that had been formerly stirred up. A change of wind direction is possible too.

30 seconds to totality

You should still be wearing your glasses. Be on the lookout for “Baily’s Beads” — the final pinpricks of sunlight shining through the valleys of the moon. They’ll last about 15 seconds or so before totality arrives.

Then the diamond ring — when the myriad beads all congeal into one lone, searing beacon.

Totality

You can only remove your eclipse glasses during totality. And when you do, you’ll be transported to another universe (figuratively speaking, of course).

Where the sun should be, you’ll see a black hole. It’s the blackest black you’ll ever see. That’s the moon blocking all incoming light.

Fanning out from behind the moon will be the sun’s wispy, diaphanous atmosphere — the corona. Hairlike strands of magnetism will be visible radiating outward.

The horizon in all directions will be glowing a delicate shade of amber — the so-called “360-degree sunrise.” Keep in mind that the moon’s shadow will only be between 100 and 120 miles wide, so the horizon literally depicts areas that are still experiencing daylight. You’re in the midst of a localized nightfall that only you get to enjoy.

Savor every second of totality. Put the phones away — they won’t capture the eclipse. Instead, treasure every fleeting moment. Time will seem to stand still, but the moment will be gone in an instant. The memories, however, will last a lifetime.

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What will happen on solar eclipse day, hours and minutes before totality