Annular solar eclipse

2019 Dec 26

The Moon’s shadow projected onto the Earth as the eclipse proceeds. The hemisphere of the Earth facing the Sun is shown. Contours show where the Sun’s disk is 0% (red), 20%, 40%, 60% and 80% covered.

You can download this video in MP4 or OGG format.

The Moon will pass in front of the Sun, creating an annular solar eclipse visible from Asia and Palau between 02:09 and 08:07 GMT.

The Moon will pass in front of the Sun, creating a solar eclipse. From some parts of the world, the alignment will be so exact that the Moon will almost completely cover the Sun.

However, because the Moon’s distance from the Earth varies and it is currently quite distant, it will not be quite large enough to completely cover the Sun. The result will be an annular eclipse, in which the Moon passes in front of the Sun but leaves a complete ring of light around its edges.

From United Kingdom no eclipse will be visible ().

The simulation to the right shows the path of the Moon’s shadow across the Earth.

The red line shows the edge of the Moon’s shadow: all places inside the red circle will see the Moon covering some part of the Sun’s disk. The yellow contours within this show where the Moon appears to cover 20%, 40%, 60% and 80% of the Sun.

The yellow spot in the centre of the Moon’s shadow traces out the thin eclipse track where an annular eclipse will be seen.

Eclipse map

The map below shows the parts of the world where the eclipse will be visible, which are highlighted within the red contour. The yellow contours show the maximum extent of the eclipse, where the Moon appears to cover 20%, 40%, 60% and 80% of the Sun.

Map of the total solar eclipse of December 2019

Eclipse alignment

Solar eclipses occur when the Sun, Moon and Earth are aligned in an almost exact straight line, with the Moon in the middle, such that the Moon passes in front of the Sun.

The Moon passes close to the Sun in the sky every month, at new moon, but because the Moon’s orbit is tipped up by 5° relative to the Earth’s orbit around the Sun, the alignment usually isn’t exact. As a result, the Moon usually passes a few degrees to the side of the Sun.

Even when eclipses do occur, they are not visible from the whole world at once. The Moon casts a circular shadow onto the Earth, but because the Moon is much smaller than the Earth, the shadow doesn’t cover the whole planet. Over time, the shadow sweeps across the Earth, so that different places see the eclipse at different times.

The eclipse path

A simulation of how the eclipse will appear from London.

Time:       Altitude: °      Azimuth: °

The chart to the right simulates how the eclipse will appear from London between 02:17 and 08:17 GMT. The yellow disk represents the Sun, while the black disk represents the Moon. No eclipse is visible from London, and so the Moon never quite passes in front of the Sun.

The path of the annular eclipse will pass through India, Indonesia, Malaysia, Oman, Palau, Qatar, Singapore and United Arab Emirates.

Additionally, a partial eclipse will be much more widely visible, from countries including:

Country Percentage of
Sun covered
Federated States of Micronesia 92%
Iran 90%
Saudi Arabia 89%
Sri Lanka 89%
Guam 89%
Philippines 89%
Northern Mariana Islands 87%
Brunei 85%
Pakistan 83%
Thailand 83%
Bahrain 83%

As seen from any given location, this annular eclipse will last for a maximum of 3 minutes.

Below, the path of the Moon’s shadow is projected onto a flat map of the world. As above, the red contour shows the edge of the Moon’s shadow, and encloses everywhere where the eclipse can be seen. The yellow contours show where the Sun is 20%, 40%, 60% and 80% covered.

You can download this video in MP4 or OGG format.

Eclipse safety

The geometry of a solar eclipse

Solar eclipses take place when the Earth moves through the Moon’s shadow. The dark gray cone behind the Moon indicates the region of space in which the Moon appears to completely cover the Sun’s disk (the Moon’s umbra). The light gray area around it shows where the Moon appears to partially cover the Sun’s disk (the Moon’s penumbra).

Observing the Sun can be very dangerous if it is not done with the right equipment. The Sun is the brightest object in the sky, and looking directly at it can cause permanent eye damage within seconds. Viewing it through any optical instrument – even a pair of binoculars or the finderscope on the side of your telescope – can cause instant and permanent blindness.

If you have any doubts about whether your equipment is safe, it is best not to risk using it. By far the safest thing to do is to go along to a public observing event. Many astronomical societies are likely to be hosting observing events on the day, and they’ll be sure to welcome newcomers. You may meet some

This entry in the observing calendar was provided by In-The-Sky.org

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