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Starts With A Bang

7 Fascinating Facts About 2019’s Only Total Solar Eclipse

The total solar eclipse of July 2, 2019, is the longest one we’ll have until 2027. And that’s not all.

On July 2, 2019, the new Moon will pass between Earth and our Sun, creating a total solar eclipse.

The path of totality for the July 2, 2019 total solar eclipse will take it from the western Pacific Ocean to South America, where it will cross Chile and Argentina before disappearing into the sunset. (XAVIER M. JUBIER, VIA XJUBIER.FREE.FR)

Here’s what you should know before totality occurs over South America.

The only land mass that the total solar eclipse of July 2, 2019 will encounter is a small portion of Chile and Argentina in South America. The remainder will occur over the oceans. (NASA / SCIENTIFIC VISUALIZATION STUDIOS)

1.) Only a small sliver of Earth will experience totality.

An image of the 1999 total solar eclipse as seen from space, with the Moon’s shadow clearly visible on the surface of the Earth. While only a small region of Earth experiences a total solar eclipse at any given time, a total lunar eclipse can be seen from anywhere on the night side of Earth. Fortunately, internet live-streams can give a portion of the experience to people located anywhere on Earth. (MIR / RSA, 1999)

Chile and Argentina are the only land masses to experience totality this time; the remainder occurs exclusively over oceans.

This artist’s impression shows how the total solar eclipse of 2 July 2019 could appear from ESO’s La Silla Observatory in Chile if there are no clouds. The Sun will be quite low in the western sky and, if the skies are clear, several planets and bright stars should be also visible. Three of the world’s great ground-based observatories — Cerro Tololo Inter-American Observatory (CTIO), Gemini South, and La Silla Observatory — will fall into the path of totality. (M. DRUCKMÜLLER, P. ANIOL, K. DELCOURTE, P. HORÁLEK, L. CALÇADA/ESO)

2.) This is the greatest eclipse ever for astronomers.

The top of Cerro Pachon mountain houses a number of astronomical observatories, including Gemini South, as part of Cerro Tololo Observatory. The future LSST (Large Synoptic Survey Telescope) will also be located here. (EKX64 HERNÁN STOCKEBRAND / WIKIMEDIA COMMONS)

Three world-class observatories, including the 8-meter Gemini South, will experience totality.

A wide-angle, long-exposure view of a total solar eclipse can reveal incredible features that are otherwise invisible during the day. These features include background stars, plasma loops on the Sun, the solar corona extending a great distance, and much more. The longer the eclipse, the darker the skies and the more the Sun’s corona and background stars are visible. At 4 minutes and 33 seconds of totality at maximum, this will be nearly twice as long as the total solar eclipse of 2017. (MILOSLAV DRUCKMULLER, PETER ANIOL)

3.) Optimally situated viewers will experience 4 minutes and 33 seconds of totality.

An illustration of the Sun-Moon-Earth configuration setting up a total solar eclipse. When the Moon’s shadow falls on Earth when the nearer-to-the-Sun node aligns, we get a solar eclipse, only visible across a narrow band of Earth’s surface. Conversely, when the away-from-the-Sun node aligns with the Earth-Sun plane, the Moon passes through Earth’s shadow and gives us a lunar eclipse, which is visible to everyone on the night side of Earth. The Moon is near perigee on July 2nd (which it will reach on July 5th), while the Sun is near aphelion (which it will reach on July 4th). (STARRY NIGHT EDUCATION SOFTWARE)

With Earth near aphelion and the Moon near perigee, it’s nearly twice the duration of 2017’s eclipse.

The eclipsed Sun, the visible corona, and the reddish hues around the edges of the Moon’s shadow — along with human beings rapt with awe — were among the most spectacular sights of the 2017 total eclipse. Total solar eclipses are the best time for viewing the Sun’s corona from Earth; no coronagraph is as good as the Moon is as far as blocking the ambient sunlight. (JOE SEXTON / JESSE ANGLE)

4.) This is a one-shot deal to gain unparalleled scientific knowledge.

32 images collected from the 2016 eclipse were combined in order to produce this composite, showcasing not only the corona and the plasma loops above the photosphere with stars in the background, but also with the Moon’s surface illuminated by Earthshine. The inner regions of the Sun’s corona are best observed, scientifically, during a total solar eclipse. These observations can teach us about the Sun’s magnetic field, coronal temperature, composition, and density, as well as what elements, ions and molecules are excited enough to produce emission lines. (DON SABERS, RON ROYER, MILOSLAV DRUCKMULLER)

Coronal imaging, spectroscopy, polarization, and emission line data are collectible during totality.

The first ‘bead’ of light to reappear, as totality ends during a total solar eclipse, poses the greatest danger to both human eyes and astronomical equipment. Just as direct sunlight can burn a hole in your retina, it can destroy (or ‘fry,’ as astronomers say) the optics of any telescope system. For a state-of-the-art ground-based telescope, this could result in millions of dollars worth of damage. (RICARDO GARZA-GRANDE)

5.) Eclipse viewing is extremely dangerous for astronomical equipment.

The interior and the primary mirror of the GTC, the largest single optical telescope in the world today. Telescope mirrors have special coatings applied to them, but are designed to measure and focus extremely faint amounts of light. Even a brief amount of exposure to direct sunlight could overload and destroy the entirety of the downstream equipment, as well as the coatings on the primary and secondary mirrors. (MIGUEL BRIGANTI (SMM/IAC))

A single second of accidental direct-sunlight exposure can ruin the optics on a telescope.

The eclipse will be broadcast from Chile in South America, which is on the same timezone as Eastern Time in the United States: 6 hours behind Central European Summer Time. You can convert from the time of totality for the broadcast eclipse (approximately 4:30 PM local time) to your timezone using the color-codes on this map.(TIMEANDDATE.COM)

6.) The eclipse will be broadcast across the entire world.

From 7:23 PM to 9:46 PM UTC, The Exploratorium and NASA will partner to live-stream the eclipse worldwide.

The total eclipse, as seen in Madras, Oregon in this picture, resulted in not only a spectacular view of the Sun, but of the horizon surrounding everyone in the path of totality. As the Moon moves to block the Sun, smaller and smaller fractions of sunlight strike the Earth, causing the temperatures to drop. With the July 2, 2019 eclipse occurring in the afternoon and with such a long duration, temperatures may drop by near-record amounts. Typically, temperatures drop during a total solar eclipse by approximately 10 degrees Fahrenheit, although drops as large as 28 degrees have been recorded. (ROB KERR/AFP/GETTY IMAGES)

7.) Temperatures may drop by over 20 °F (12 °C).

The Sun’s atmosphere is not confined to the photosphere or even the corona, but rather extends out for millions of miles in space, even under non-flare or ejection conditions. Although we can apply a coronagraph to view the extended conditions, no artificial coronagraph blocks out the Sun or allows for the quality of views like the Moon does. (NASA’S SOLAR TERRESTRIAL RELATIONS OBSERVATORY)

The long duration will bring darker skies, more stars, and improved viewsof the Sun’s extended corona.

The pink ‘fringe’ around the circumference of the Moon is actually due to plasma loops rising above the photosphere of the Sun. This hot plasma links up with the corona, eventually, and extends great distances into space. The corona itself is 10,000 brighter than the new Moon. (UPICE OBSERVATORY, PETR HORALEK, JAN SLADECEK, MILOSLAV DRUCKMULLER)

Mostly Mute Monday tells an astronomical story in images, visuals and no more than 200 words. Talk less; smile more.

Ethan Siegel is the author of Beyond the Galaxy and Treknology. You can pre-order his third book, currently in development: the Encyclopaedia Cosmologica.


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