Stages of a Total Eclipse

The August 21st total eclipse of the Sun lasts several hours. During this period, there and many interesting events and effects to be looking for. In the following excerpt from Totality – The Great America Eclipses of 2017 and 2024, this handy checklist will help you keep track of what and when to look for each of these must see events and effects. You might even want to print this page as a handy reference on eclipse day.

A series of nine images were combined into a time sequence of the total solar eclipse of 1999 August 11, from Lake Hazar, Turkey. The corona has been computer enhanced to show subtle details and prominences. Copyright 1999 by Fred Espenak.

A series of nine images were combined into a time sequence of the total solar eclipse of 1999 August 11, from Lake Hazar, Turkey. The corona has been computer enhanced to show subtle details and prominences. Copyright 1999 by Fred Espenak.

First Contact – The Moon begins to cover the western limb of the Sun. Remember to use safe solar filters to watch the partial phases of the eclipse.

Crescent Sun – Over a period of about an hour, the Moon obscures more and more of the Sun, as if eating away at a cookie. The Sun appears as a narrower and narrower crescent.

Light and Color Changes – About 15 minutes before totality, when 80% of the Sun is covered, the light level begins to fall noticeably—and with increasing rapidity. The landscape takes on a metallic gray-blue hue.

Animal, Plant, and Human Behavior – As the level of sunlight falls, animals may become anxious or behave as if nightfall has come. Some plants close up. Notice how the people around you are affected.

Gathering Darkness on the Western Horizon – About 5 minutes before totality, the shadow cast by the Moon causes the western horizon to darken as if a giant but silent thunderstorm was approaching.

Temperature – As the sunlight fades, the temperature may drop perceptibly.

Shadow Bands – A minute or two before totality, ripples of light may flow across the ground and walls as Earth’s turbulent atmosphere refracts the last rays of sunlight.

Thin Crescent Sun – Only a sliver of the Sun remains, then thinner still until . . .

Corona – Perhaps 15 seconds before totality begins, as the Sun becomes the thinnest of crescents, the corona begins to emerge.

Diamond Ring Effect – As the corona emerges, the crescent Sun has shrunk to a short, hairline sliver. Together they form a dazzlingly bright diamond ring. Then the brilliant diamond fades into . . .

Baily’s Beads – About 3 seconds before totality begins, the remaining crescent of sunlight breaks into a string of beads along the eastern edge of the Moon. These are the last few rays of sunlight passing through deep valleys at the Moon’s limb, creating the momentary effect of jewels on a necklace. Quickly, one by one, Baily’s beads vanish behind the advancing Moon as totality begins.

Shadow Approaching – While all this is happening, the Moon’s dark shadow in the west has been growing. Now it rushes forward and envelops you.

Second Contact Totality Begins – The Sun’s disk (photosphere) is completely covered by the Moon. You can now remove your solar filters and safely look directly at the eclipse.

Prominences and the Chromosphere – For a few seconds after totality begins, the Moon has not yet covered the lower atmosphere of the Sun and a thin strip of the vibrant red chromosphere is visible at the Sun’s eastern limb. Stretching above the chromosphere and into the corona are the vivid red prominences. A similar effect occurs along the Sun’s western limb seconds before totality ends.

This image of the solar corona is a High Dynamic Range composite made from 22 separate exposures. The original images were shot by Espenak in Jalu, Libya during the total solar eclipse of March 29, 2016. The USPS used this image to create the Total Eclipse of the Sun, Forever® stamp.

This image of the solar corona is a High Dynamic Range composite made from 22 separate exposures. The original images were shot by Espenak in Jalu, Libya during the total solar eclipse of March 29, 2016. The USPS used this image to create the Total Eclipse of the Sun, Forever® stamp.

Corona Extent and Shape – The corona and prominences vary with each eclipse. How far (in solar diameters) does the corona extend? Is it round or is it broader at the Sun’s equator? Does it have the appearance of short bristles at the poles? Look for loops, arcs, and plumes that trace solar magnetic fields.

Planets and Stars Visible – Venus and Mercury are often visible near the eclipsed Sun, and other bright planets and stars may also be visible, depending on their positions and the Sun’s altitude above the horizon.

Landscape Darkness and Horizon Color – Each eclipse creates its own level of darkness, depending mostly on the Moon’s angular size. At the far horizon all around you, beyond the Moon’s shadow, the Sun is shining and the sky has twilight orange and yellow colors.

Temperature – Is it cooler still? A temperature drop of about 10°F (6°C) is typical. The temperature continues to drop until a few minutes after third contact.

Animal, Plant, and Human Reactions – What animal noises can you hear? How are other people reacting? How do you feel?

End of Totality Approaching – The western edge of the Moon begins to brighten and vividly red prominences and the chromosphere appear. Totality will end in seconds.

Third Contact – One bright point of the Sun’s photosphere appears along the western edge of the Moon. Totality is over. The stages of the eclipse repeat themselves in the reverse order.

Baily’s Beads – The point of light becomes two, then several beads, which fuse into a thin crescent with a dazzling bright spot emerging, a farewell diamond ring.

Diamond Ring Effect and Corona – As the diamond ring brightens, the corona fades from view. Daylight returns.

Shadow Rushes Eastward

Shadow Bands Reappear – Shadow Bands may be seen during the first 1-2 minutes after totality ends.

Crescent Sun – Partial phases occur in reverse order. Once again, you must use your solar filter to watch all the partial phases of the eclipse.

Recovery of Nature Partial Phase – Flowers open up, animals return to normal behavior, daylight regains its strength.

Fourth Contact – The Moon no longer covers any part of the Sun. The eclipse is over.

diamond ring effect

As totality ends, the Sun begins to emerge from behind the Moon producing the dazzling diamond ring effect. Copyright 2016 by Fred Espenak.

Learn all about the Best Ways to View the Solar Eclipse and well as what it is like to Experience Totality.

You may also be interested in the 2017 Eclipse Stamp as well as a post about Total Solar Eclipses in the USA.

Totality – The Great America Eclipses of 2017 and 2024

Read much more in Totality – The Great America Eclipses of 2017 and 2024 by Mark Littmann and Fred Espenak.

Read much more in Totality – The Great America Eclipses of 2017 and 2024 by Mark Littmann and Fred Espenak.

About the Authors

Mark Littmann has written several popular books about astronomy. Planets Beyond: Discovering the Outer Solar System won the Science Writing Award of the American Institute of Physics. Planet Halley: Once in Lifetime (Donald K Yeomans, co-author) won the Elliott Montroll Special Award of the New York Academy of Sciences. Reviewers described The Heavens on Fire: The Great Leonid Meteor Storms as a “unique achievement,” “altogether satisfying,” and “a compelling read.”

Mark holds an endowed professorship, the Hill Chair of Excellence in Science Writing, at the University of Tennessee where he teaches three different courses in writing about science, technology, medicine, and the environment. He has helped lead expeditions to Canada, Hawaii, Bolivia, Aruba, and Turkey to observe total eclipses.

Fred Espenak is the most widely recognized name in solar eclipses. He is an astrophysicist emeritus at NASA’s Goddard Space Flight Center, where he founded and runs the NASA Eclipse Home Page, the most consulted website for eclipse information around the globe. His Five Millennium Canons of solar and lunar eclipses are seminal works for researchers, archaeologists, and historians.

Fred writes regularly on eclipses for Sky amp; Telescope and is probably the best known of all eclipse photographers. He leads expeditions for every total solar eclipse and has done so for more than 35 years. In 2003, the International Astronomical Union honored Espenak and his eclipse work by naming asteroid 14120 after him. The U. S. Postal Service recently used one of his photos on a postage stamp to commemorate the 2017 total eclipse of the Sun.

Fred Espenak


Events for August 2017

The following table gives the date and time of important astronomical events for August 2017.

The time of each event is given in Greenwich Mean Time or GMT (a.k.a. Universal Time or UT). To convert GMT to Eastern Standard Time (EST) just subtract 5 hours. To convert GMT to other time zones, visit Time Zones. Some of the astronomical terms used in the calendar are explained in Definitions.

 Date    GMT   Astronomical Events for August 2017
------  -----  --------------------------------------------
        (h:m)
Aug 02  13     Mercury at Aphelion 
Aug 02  17:55  Moon at Apogee: 405026 km
Aug 03  07:31  Saturn 3.5°S of Moon
Aug 07  18:11  FULL MOON 
Aug 07  18:20  Partial Lunar Eclipse; mag=0.246
Aug 08  10:56  Moon at Descending Node 
Aug 12  19     Perseid Meteor Shower
Aug 15  01:15  LAST QUARTER MOON 
Aug 16  06:39  Aldebaran 0.4°S of Moon
Aug 18  13:14  Moon at Perigee: 366129 km
Aug 19  04:45  Venus 2.2°N of Moon
Aug 20  07:15  Beehive 3.2°N of Moon
Aug 20  18:08  Venus 7.2°S of Pollux
Aug 21  10:34  Moon at Ascending Node 
Aug 21  18:26  Total Solar Eclipse; mag=1.031
Aug 21  18:30  NEW MOON 
Aug 25  13:00  Jupiter 3.5°S of Moon
Aug 26  21     Mercury at Inferior Conjunction 
Aug 29  08:13  FIRST QUARTER MOON 
Aug 30  11:25  Moon at Apogee: 404307 km
Aug 30  14:23  Saturn 3.6°S of Moon

As the events above transpire, I will post photographs of some of them at Recent Images.

Astronomical events calendars for complete years and for eight time zones are available through the links below.

Time Zones Calendars of Astronomical Events
Greenwich Mean Time 2017 2018 2019 2020 2021 2022
Atlantic Standard Time 2017 2018 2019 2020 2021 2022
Eastern Standard Time 2017 2018 2019 2020 2021 2022
Central Standard Time 2017 2018 2019 2020 2021 2022
Mountain Standard Time 2017 2018 2019 2020 2021 2022
Pacific Standard Time 2017 2018 2019 2020 2021 2022
Alaska Standard Time 2017 2018 2019 2020 2021 2022
Hawaii Standard Time 2017 2018 2019 2020 2021 2022

For additional years, see Calendars of Astronomical Events.

The astronomical highlight of 2017 is the Great American Total Solar Eclipse on August 21. This is the first total eclipse visible from the continental USA in 38 years. For complete details on this highly anticipated event, see: 2017 Total Solar Eclipse (EclipseWise.com).

For information on all solar and lunar eclipses this year, see: Eclipses During 2017.

The Calendars of Astronomical Events were all generated by a computer program I wrote (with THINK Pascal running on a Macintosh G4) using Astronomical Algorithms (Jean Meeus).

Fred Espenak



Best Ways to View the Solar Eclipse

Millions of people will soon travel to a narrow strip in America to witness a rare event: a total solar eclipse. On 21 August, many will look up to the sky to witness this phenomenon – will you be one of them? In the following shortened excerpt from Totality – The Great America Eclipses of 2017 and 2024, learn what types of eyewear you should be using to watch the Sun disappear, when you can do away with eye protection completely, and other ways to best view this event.

You would never think of staring at the Sun without eye protection on an ordinary day. You know the disk of the Sun is dazzlingly bright, enough to permanently damage your eyes. Likewise, any time the disk of the Sun is visible – throughout the partial phase of an eclipse – you need proper eye protection. Even when the Sun is nearing total eclipse, when only a thin crescent of the Sun remains, the 1% of the Sun’s surface still visible is about 10,000 times brighter than the Full Moon.

Once the Sun is entirely eclipsed, however, its bright surface is hidden from view and it is completely safe to look directly at the totally eclipsed Sun without any filters. In fact, it is one of the greatest sights in nature. Here are ways to observe the partial phases of a solar eclipse without damaging your eyes.

Solar Eclipse Glasses

The most convenient way to watch the partial phases of an eclipse is with solar eclipse glasses. These devices consist of solar filters mounted in cardboard frames that can be worn like a pair of eyeglasses. If you normally wear prescription eyeglasses, you place the eclipse glasses right in front of them.

When you are using a filter, do not stare for long periods at the Sun. Look through the filter briefly and then look away. In this way, a tiny hole that you miss will not cause you any harm. You know from your ignorant childhood days that it is possible to glance at the Sun and immediately look away without damaging your eyes. Just remember that your eyes can be damaged without you feeling any pain.

A Samburu man wears a pair of eclipses glasses in preparation for an annular eclipse in Kenya. These inexpensive glasses with cardboard frames have become very popular for safe eclipse viewing. [©2010 Fred Espenak]

Welder’s Goggles

Another safe filter for looking directly at the Sun is welder’s goggles (or the filters for welder’s goggles) with a shade of 13 or 14. They are relatively inexpensive and can be purchased from a welding supply company. The down side is that they cost more than eclipse glasses and give the Sun an unnatural green cast.

The Pinhole Projection Method

If you don’t have eclipse glasses or a welder’s filter, you can always make your own pinhole projector, which allows you to view a projected image of the Sun. There are fancy pinhole cameras you can make out of cardboard boxes, but a perfectly adequate (and portable) version can be made out of two thin but stiff pieces of white cardboard. Punch a small clean pinhole in one piece of cardboard and let the sunlight fall through that hole onto the second piece of cardboard, which serves as a screen, held behind it. An inverted image of the Sun is formed. To make the image larger, move the screen farther from the pinhole. To make the image brighter, move the screen closer to the pinhole. Do not make the pinhole wide or you will have only a shaft of sunlight rather than an image of the crescent Sun. Remember, a pinhole projector is used with your back to the Sun. The sunlight passes over your shoulder, through the pinhole, and forms an image on the cardboard screen behind it. Do not look through the pinhole at the Sun.

A pinhole projector can be used to safely watch the partial phases of a solar eclipse. It is easily fashioned from two stiff pieces of cardboard. One piece serves as the projection screen. Make a pinhole in the second piece and hold it between the Sun and the first piece. If the two cardboards are held 2 feet apart the projected image of the Sun will appear about 1/4-inch in size. [Drawing by Fred Espenak]

Even a simple pasta colander can be used to project dozens of images of the eclipsed Sun onto a piece of white cardboard. [©2000 Fred Espenak]

Solar Filters for Cameras, Binoculars, and Telescopes

Many telescope companies provide special filters that are safe for viewing the Sun. Black polymer filters are economical but some observers prefer the more expensive metal-coated glass filters because they produce sharper images under high magnification.

Caution: Do not confuse these filters, which are designed to fit over the front of a camera lens or the aperture of a telescope, with a so-called solar eyepiece for a telescope. Solar eyepieces are still sometimes sold with small amateur telescopes. They are not safe because they absorb heat and tend to crack, allowing the sunlight concentrated by the telescope’s full aperture to enter your eye.

Eye Suicide

Do not use standard or polaroid sunglasses to observe the partial phases of an eclipse. They are not solar filters. Standard and polaroid sunglasses cut down on glare and may afford some eye relief if you are outside on a bright day, but you would never think of using them to stare at the Sun. So you must not use sunglasses, even crossed polaroids, to look directly at the Sun during the partial phases of an eclipse.

Do not use smoked glass, medical x-ray film with images on them, photographic neutral-density filters, and polarizing filters. All these “filters” offer utterly inadequate eye protection for observing the Sun.

Observing with Binoculars

Binoculars are excellent for observing total eclipses. Any size will do. Astronomy writer George Lovi’s favorite instrument for observing eclipses was 7 x 50 binoculars – magnification of seven times with 50-millimeter (2-inch) objective lenses. “Even the best photographs do not do justice to the detail and color of the Sun in eclipse,” Lovi said, “especially the very fine structure of the corona, with its exceedingly delicate contrasts that no camera can capture the way the eye can.” He felt that the people who did the best job of capturing the true appearance of the eclipsed Sun were the 19th century artists who photographed totality with their eyes and minds and developed their memories with paints on canvas.

For people who plan to use binoculars on an eclipse, Lovi cautioned common sense. Totality can and should be observed without a filter, whether with the eyes alone or with binoculars or telescopes. But the partial phases of the eclipse, right up through the diamond ring effect, must be observed with filters over the objective (front) lenses of the binoculars. Only when the diamond ring has faded is it safe to remove the filter. And it is crucial to return to filtered viewing as totality is ending and the western edge of the Moon’s silhouette brightens with the appearance of the second diamond ring. After all, binoculars are really two small telescopes mounted side by side. If observing a partially eclipsed Sun without a filter is quickly damaging to the unaided eyes, it is far quicker and even more damaging to look at even a sliver of the uneclipsed Sun with binoculars that lack a filter.

Binoculars can be used to safely project a magnified image of the Sun onto a piece of white cardboard. Never look at the Sun directly through binoculars unless they are equipped with solar filters. [©2000 Fred Espenak]

Totality – The Great America Eclipses of 2017 and 2024

Read much more in Totality – The Great America Eclipses of 2017 and 2024 by Mark Littmann and Fred Espenak.

Read much more in Totality – The Great America Eclipses of 2017 and 2024 by Mark Littmann and Fred Espenak.

About the Authors

Mark Littmann has written several popular books about astronomy. Planets Beyond: Discovering the Outer Solar System won the Science Writing Award of the American Institute of Physics. Planet Halley: Once in Lifetime (Donald K Yeomans, co-author) won the Elliott Montroll Special Award of the New York Academy of Sciences. Reviewers described The Heavens on Fire: The Great Leonid Meteor Storms as a “unique achievement,” “altogether satisfying,” and “a compelling read.”

Mark holds an endowed professorship, the Hill Chair of Excellence in Science Writing, at the University of Tennessee where he teaches three different courses in writing about science, technology, medicine, and the environment. He has helped lead expeditions to Canada, Hawaii, Bolivia, Aruba, and Turkey to observe total eclipses.

Fred Espenak is the most widely recognized name in solar eclipses. He is an astrophysicist emeritus at NASA’s Goddard Space Flight Center, where he founded and runs the NASA Eclipse Home Page, the most consulted website for eclipse information around the globe. His Five Millennium Canons of solar and lunar eclipses are seminal works for researchers, archaeologists, and historians.

Fred writes regularly on eclipses for Sky amp; Telescope and is probably the best known of all eclipse photographers. He leads expeditions for every total solar eclipse and has done so for more than 35 years. In 2003, the International Astronomical Union honored Espenak and his eclipse work by naming asteroid 14120 after him. The U. S. Postal Service recently used one of his photos on a postage stamp to commemorate the 2017 total eclipse of the Sun.

Fred Espenak