“Annular eclipses are similar to total eclipses in that the moon, Earth and sun are aligned so that the moon moves directly in front of the Sun as viewed from Earth,” said Alex Young, associate director for science in the heliophysics science division at NASA’s Goddard Space Flight Center.
“But a total eclipse does not happen, that is the moon does not completely block out the visible disk of the sun because the moon is farther away and so its apparent size in the sky is [slightly] smaller than the sun. This means that a tiny ring of annulus of the solar disk is visible around the moon.”
Solar eclipses occur about two weeks before or after a lunar eclipse, Young said. There was a lunar eclipse on June 5 and the next one occurs on July 5.
The annular eclipse will begin at 12:47 a.m. ET (4:47 UTC) on June 21 and cross a skinny path that starts at sunrise in Africa and eventually moves across to China before ending at sunset over the Pacific Ocean. It will peak at 2:40 a.m. ET (6:40 UTC) and end around 4:32 a.m. ET (8:32 UTC).
The partial eclipse will begin at 11:45 p.m. ET (3:45 UTC) on June 20 and end at 5:34 a.m. ET (9:34 UTC) on June 21.
It will be visible over central Africa, the southern Arabian Peninsula, Pakistan, Northern India and South Central China, Young said. A partial eclipse will be seen over most of Asia, Africa, South and East Europe, northern Australia and parts of the Pacific and Indian Oceans, he added.
And of course, this is weather permitting, so hopefully the skies will be clear.
The entire eclipse will last about 3.75 hours, but the duration as it passes over individual locations will equal to around a minute and a half. During the peak, that will actually shorten to just over 30 seconds.
How to watch
Although this isn’t a total solar eclipse, you still need to watch the eclipse using safety measures.
“Because the Sun is so incredibly bright, it is still too bright to look at with unprotected eyes,” Young said. “You need safe solar viewing glasses or special filters for use with telescopes or binoculars.”
Any glimpse of the sun’s brightness is not only uncomfortable — it’s dangerous. Looking directly at the powerful brightness of the sun can cause damage to the retina, the light-sensitive part of the eye. Even the smallest amount of exposure can cause blurry vision or temporary blindness. The problem is, you won’t know whether it’s temporary at first.
Whether you use the cardboard eclipse glasses or a handheld card with a single rectangular view, the most important feature is the filter. Make sure your eclipse glasses meet the ISO 12312-2 international safety standard. Eclipse glasses can be worn over regular eyeglasses.
To test for safety, the only thing you can see through a safe solar filter is the sun itself. If you look through and the sun is too bright, out of focus or surrounded by a murky haze, or if you can see things like ordinary household lights, the glasses aren’t safe.
If you’re tempted to reuse eclipse glasses that are three years or older, they were made before the international safety standard was in place and come with a warning that says you can’t look through them for more than three minutes at a time. These should be discarded, according to the American Astronomical Society.
If you plan on watching the eclipse through a camera, a telescope or binoculars, buy a solar filter to place on the end of the lens. But do not wear eclipse glasses while looking through any of these. The concentrated light will go right through the filters and cause injury to your eyes.
Here are safety tips to remember, according to the American Astronomical Society:
- Always inspect your solar filter before use; if it’s scratched, punctured, torn or otherwise damaged, discard it. Read and follow any instructions printed on or packaged with the filter.
- Always supervise children using solar filters.
- If you normally wear eyeglasses, keep them on. Put your eclipse glasses on over them, or hold your handheld viewer in front of them.
- Stand still and cover your eyes with your eclipse glasses or solar viewer before looking up at the bright sun. After looking at the sun, turn away and remove your filter; do not remove it while looking at the sun.
- Do not look at the uneclipsed or partially eclipsed sun through an unfiltered camera, telescope, binoculars or other optical device.
- Similarly, do not look at the sun through a camera, a telescope, binoculars or any other optical device while using your eclipse glasses or handheld solar viewer; the concentrated solar rays could damage the filter and enter your eyes, causing serious injury.
- Seek expert advice from an astronomer before using a solar filter with a camera, telescope, binoculars or any other optical device; note that solar filters must be attached to the front of any telescope, binoculars, camera lens or other optics.