Solar eclipse: South America, Pacific to see sun and moon align July 2

At 4:39 p.m. local time tomorrow, July 2, fish of the south Pacific and some lucky people in southern Chile and Argentina will be plunged into rare afternoon darkness.

It will be the first total solar eclipse since August 21, 2017, and the only only celestial event of its kind in 2019.

During a total solar eclipse, the moon passes between Earth and the sun, casting a small, dark shadow on our planet. For those watching on Earth, the moon appears to cover the sun, with a ring of the sun’s light surrounding the moon. Looking directly at that light requires special glasses to protect the eyes from the sun’s brightness.

The eclipse’s path of totality — in which the sun is fully blocked from view by the moon — is an ample length of 6,000 miles, though most of that is over the Pacific Ocean and a narrow band of Chile and Argentina.

Viewers in South America will experience totality for about 2.5 minutes, roughly the same duration as the 2017 eclipse that crossed the continental US. La Serena, a city on Chile’s western coast, will be the first to go dark.

Totality will last the longest over a remote part of the Pacific Ocean west of South America, where the sun will go dark for 4 minutes and 32 seconds. (That point is represented by the black sun in the map below.)

The late timing for tomorrow’s eclipse means that totality occurs will occur about one hour and 18 minutes before sunset, when the sun is low in the sky — just 13 degrees above the horizon.

That could make viewing the event a bit challenging, since low-lying clouds could obscure the spectacle. Researchers will also need to peer through more of Earth’s hazy atmosphere to get a clear image of what’s happening in the sky.

Totality represents a unique opportunity for scientists who study the sun. It’s the only time that the solar corona — the sheath of high-speed, super-hot particles that ensconce the sun — is visible to onlookers.

Occasionally, the corona spits out bursts of scorching hot plasma, which can be between 1.7 million degrees Fahrenheit and more than 17 million degrees— hotter than the surface of the sun itself. These bursts, called coronal mass ejections, can hurl towards Earth at speeds of 1,384 miles per second. Their effects can disrupt our telecommunications infrastructure, knock out power grids, and impact satellites in orbit.

By observing and analyzing the corona’s behavior during eclipses, scientists gather information that can help them better understand and predict these coronal mass ejections.

The next total solar eclipse will happen less than 18 months after this one. On December 14, 2020 another total eclipse will travel over Chile and Argentina.

The next total solar eclipse that people will be able to see from North America will happen on April 8, 2024.