© Mrpulley. Taken from Tennant Creek, Northern Territory, Australia in May 2013.

Annular solar eclipse

Dominic Ford, Editor
From the Eclipses feed

Time:       Altitude: °      Azimuth: °

A simulation of how the eclipse will appear from Ashburn.


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.

The path of the annular eclipse will pass through Indonesia.

A partial eclipse will be seen from numerous other countries, including:

CountryExtent of eclipse
Cocos IslandsSun 85% covered
Christmas IslandSun 83% covered
PhilippinesSun 82% covered
French Southern TerritoriesSun 81% covered
South AfricaSun 81% covered
MalaysiaSun 80% covered

From United States no eclipse will be visible. To see information about the times when the eclipse will be visible elsewhere in the world, select a different location.

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

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 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 white contours within this show where the Moon appears to cover 20%, 40%, 60% and 80% of the Sun.

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

As seen from any given location, this annular eclipse will last for a maximum of 7 minutes.

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

You can download this video in MP4 or OGG format.

The map below shows a still image mapping the maximum extent of the eclipse across the world. The red contour encloses all places in which any part of the eclipse is visible.

Map of the total solar eclipse of January 2009

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 new people at the same time as seeing the transit.

Many astronomy suppliers sell special special filters which are made for safe solar viewing. These include aluminised mylar filters, or black polymer filters, identified as suitable for direct viewing of the Sun. Check that the filter has a CE mark, and a statement that it conforms to European Community Directive 89/686/EEC. Alternatively, you can use a welder's glass rated at No. 14 or higher. Always read the manufacturer's instructions carefully.

Never attempt to make your own filter. In addition to visible light, the Sun also produces prodigious amounts of infrared and ultraviolet radiation which cannot be seen yet can still damage your eye. Even if a homebrew filter appears adequate, it may allow this unseen radiation to pass.

Projecting an image of the Sun

Two example of low-cost cardboard solar projection boxes. These two are sold in the UK by Green Witch.

Another safe way to view solar eclipses is to buy a purpose-built solar projection box.

These typically consist of a cardboard box with a small lens on one side. They project an enlarged image of the Sun onto a white cardboard sheet inside the box. Once the transit is over, they're also great for observing sunspots. They are safe to use, quick to set up, and ideal for use with children and groups.

To my knowledge, the only UK supplier who sells these is Green Witch. They sell a Sun Projector Kit for £18, or a sturdier Lightec Solar Projection Telescope for £50.

Further details

This eclipse is a member of Saros series 131. The position of the Sun at the moment of greatest eclipse will be:

Object Right Ascension Declination Constellation Angular Size
Sun (centre) 20h35m -18°40' Capricornus 32'29"

The coordinates above are given in J2000.0.

The sky on 26 May 2018
Sunrise
05:47
Sunset
20:23
Twilight ends
22:16
Twilight begins
03:54

11-day old moon
Waxing Gibbous

90%

11 days old

Planets
Rise Culm. Set
Mercury 05:14 12:16 19:18
Venus 07:57 15:29 23:01
Moon 17:43 23:16 04:19
Mars 00:32 05:19 10:07
Jupiter 18:34 23:46 05:02
Saturn 22:38 03:28 08:13
All times shown in EDT.

Warning

Never attempt to point a pair of binoculars or a telescope at an object close to the Sun. Doing so may result in immediate and permanent blindness.

Source

The simulations above were derived from the DE405 ephemeris published by the Jet Propulsion Laboratory (JPL). The position of the Moon's shadow is superimposed on maps of the world taken from the NASA Visible Earth project.

The list of countries from which the eclipse is visible was computed on the basis of shape files available from DIVA-GIS.

Additional information was taken from:
Espanak, F., & Meeus, J., Five Millennium Canon of Solar Eclipses: -1999 to +3000, NASA Technical Publication TP-2006-214141 (2006)

You may embed the animations and images above in your own website. They are licensed under the Creative Commons Attribution 3.0 Unported license, which allows you to copy and/or modify them, so long as you credit In-The-Sky.org.

You can download them from:
https://in-the-sky.org/news/eclipses/solar_20090126_B.mp4
https://in-the-sky.org/news/eclipses/solar_20090126_A.mp4
https://in-the-sky.org/news/eclipses/solar_20090126.jpg

Related news

26 Jan 2009, 02:57 EST  –  New Moon
02 Feb 2009, 18:14 EST  –  Moon at First Quarter
09 Feb 2009, 09:50 EST  –  Full Moon
16 Feb 2009, 16:39 EST  –  Moon at Last Quarter

Image credit

© Mrpulley. Taken from Tennant Creek, Northern Territory, Australia in May 2013.

Ashburn

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Longitude:
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39.04°N
77.49°W
EDT

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