On Monday, most people in the U.S. should be able to see the Moon partially or totally block the Sun, weather permitting, according to NASA.

Why it matters: It will be the first total solar eclipse visible in the U.S. since 2017, and in many ways, it will overshadow that previous celestial event.

By the numbers: Because the Moon will be closer to Earth than it was in 2017, this year's path of totality will be significantly broader (108–122 miles wide) and will pass over far more people.

• Totality — or when the Moon completely blocks the Sun — will also last almost twice as long as it did in 2017. Totality will remain over four minutes long from Texas to eastern Indiana.

How it works: During a total solar eclipse, the Sun, Moon and Earth are in syzygy, or near-perfect alignment, with the Moon moving between the Sun and the Earth.

• The Moon during a total solar eclipse will cover the Sun, darkening the sky and leaving only the outermost layer of the Sun's atmosphere — its corona — visible.
• That will only be the case for those in the path of totality. Most people outside the path will instead see a partial eclipse, which makes the Sun look like a crescent.

Zoom out: In the U.S., the Moon's umbra (shadow) will pass over parts of 15 states and should completely engulf several major cities in darkness, including Dallas, Little Rock, Indianapolis, Cleveland and Buffalo, according to NASA.

• Outside of the path, people in every state, including parts of Alaska and Hawaii, will at least see a partial eclipse.

The big picture: Solar activity will be at or near maximum during the eclipse, which should give viewers a better chance to see solar phenomena, like a solar prominence or, if they're lucky, coronal mass ejections.