Shadow over the north pole and the free city

On Thursday, June 10, the Sun will appear as a burning ring around the darkened Moon.

See the end note about enlarging illustrations.

This spectacle – an annular or “ring-shaped” eclipse – will be visible only from a fairly narrow track across north-eastern Canada, north-western Greenland, the Arctic Ocean, and far eastern Siberia.  But the region over which the Sun can be seen in partial eclipse is far wider, including the north-eastern US, much of Canada, almost all of Europe, and much of Asia.

Our space view shows Earth just after the moment of New Moon, which is 10:53 Universal Time, or 5 or more hours earlier by American clocks.

The broad arrow represents the flight of Earth along the ecliptic plane in one minute.  The arrow on the equator shows how far Earth rotates in one hour.  In the background, from this viewpoint, are stars in Scorpius.

The yellow trident is sunlight coming from overhead, nearly as far north as the Tropic of Cancer at this time of year, not long before the June solstice.

The Moon has passed its ascending node, northward through the ecliptic plane, 18 hours earlier, so its shadow sweeps the northern part of Earth.  And the core of the shadow, the umbra, from within which the Sun cannot be seen, almost misses.  It tapers to an end before reaching Earth’s surface.  The dashed lines enclose the antumbra, a counter-cone, from within which the Sun can be seen as a ring around the Moon.  On the surface is the path the antumbra traces.  Ellipses along this path are the footprints of the antumbra at hourly intervals.

At essentially the mid moment of the eclipse, the antumbra goes over Earth’s north pole.  This can happen because in June the planet’s north pole is tilted toward the Sun.

It is only in total eclipse that the Moon and sky go black and the stars appear.  In annular eclipse, as in partial ones, the sky remains blue, and the Moon appears merely as a part of the blue sky, invading across the Sun.  But because of the reduced sunlight there is an eerie sense of semi-darkness.

Here are the middle stages of the eclipse as seen from the north pole.

The Sun’s outline is shown at 5-minute intervals, from 15 minutes before mid eclipse to 15 minutes after, as it appears to slide behind the Moon.  You can see that there is no stage in which the Moon completely covers the Sun.

So much for the annular component of this eclipse.  Now for the partial.

In our space view, the large gray patch marked “11:00,” slightly darker away from its edge, is the footprint of the Moon’s penumbra or partial shadow, from within which some of the Sun can be seen.  Large curves are the outlines of this penumbra at hourly intervals.  The envelope of these curves is the limit of partial eclipse.

Eclipse is slight and brief near the southern edge of this area; deeper and longer near the central path.  For north-eastern North America – roughly, north of a line from the Carolina coast to midway along the US-Canada border – the Sun will be seen about half eclipsed at and after dawn.  For Europe, partial eclipse will be toward the middle of the day. Along Mediterranean coasts, the Moon will make a barely perceptible nick in the Sun’s southern edge; for Scotland and Norway, it will cover up to 30 percent of the Sun.

Another kind of eclipse

June 4 was a sad anniversary.

Tiananmen means “Heavenly Peace Gate.”  It is the name of Beijing’s huge main square.

In 1989, demonstrations in China, led by students and protesting against one-party rule, corruption, and inequalities brought by the new market economy, spread to a hundred cities, and in Beijing swelled until a million protesters camped in Tiananmen Square.  The government of Deng Xiaoping imposed martial law and sent 300,000 troops into the city.  The number killed was about 300 according to the government, up to 3,400 according to other sources.

This image of a lone student trying to persuade the troops not to attack their fellow citizens has come to symbolize the atrocity at the Gate of Heavenly Peace.

Our Amnesty International group in Greenville worked from 1991 to 1993 for a businessman who had helped a student leader escape the crackdown after the massacre and had been sent to prison for four years (the student had got away to America).  And from 1993 to 1999 we worked for an impressively bright young couple who had been imprisoned for helping organize their fellow Foreign Ministry employees to join the march to Tiananmen Square.

In 1997 I was in Beijing, on the way from Mongolia, where I wanted to see the March 9 total solar eclipse, to Hong Kong, which I wanted to see before it was handed over from British to Chinese rule.  I walked along Beijing’s ceremonial north-south axis, past the Embrasured Gate and the mausoleum of Mao Zedong and across Tiananmen Square, overlooked by the Great Hall of the People.  An electric display ticked away the countdown of minutes and seconds to the Hong Kong handover.

Hong Kong is an amazing place, a nest of energy.  Its core, a vertical city of stairways and skyscrapers, looks down across harbors and airport runways to the surprisingly large wild hinterland that separates it from China.

Under the Sino-British Joint Declaration, Hong Kong became a special administrative region of China, retaining most of its democracy; “one country, two systems.”  This lasted till June 2019, when a law was proposed that would allow extradition of people from Hong Kong to China for trial.  It provoked massive protests, which kept on for months till the crackdown that has lost Hong Kong to the democratic world.

In China, even mentioning the June 4 “Tiananmen Square incident,” as it is called, is discouraged, and any commemoration of it is forbidden by law.  In Hong Kong, the anniversary has been a major annual event.  This picture of a past year’s occasion in Hong Kong’s Victoria Park gives a sense of the place’s excitement.

This year, for the first time, journalists in Hong Kong are not allowed to mention the event or any commemoration.

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ILLUSTRATIONS in these posts are made with precision but have to be inserted in another format.  You may be able to enlarge them on your monitor.  One way: right-click, and choose “View image”, then enlarge.  Or choose “Copy image”, then put it on your desktop, then open it.  On an iPad or phone, use the finger gesture that enlarges (spreading with two fingers, or tapping and dragging with three fingers).  Other methods have been suggested, such as dragging the image to the desktop and opening it in other ways.

Sometimes I make improvements or corrections to a post after publishing  it.  If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version.

This weblog maintains its right to be about astronomy or anything under the sun.