Annular solar eclipse — Kushiro, Hokkaido

An annular eclipse — the Moon looks slightly smaller than the Sun, leaving a ring of fire. The path runs from North Africa and Greece across Siberia to eastern Hokkaido (Kushiro, Nemuro) near sunset; Sapporo and Tokyo see a deep partial.

The moment of Annular solar eclipse — Kushiro, Hokkaido: https://nowsky.org/e/annular-eclipse-2030 — opens at the right place and time, replayable, no login.

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The story

An annular eclipse is a total eclipse that falls short. On 1 June 2030 the Moon slides exactly in front of the Sun, but it sits far enough from Earth that its disk is slightly too small to cover the solar disk completely. What remains is a thin, unbroken ring of photosphere — the "ring of fire" — and a sky that never really goes dark. That surviving ring is also why the rules for watching this eclipse are different from a total one, and stricter.

The shadow begins in Algeria, runs north across the Mediterranean into Greece and Turkey, and then sweeps a long diagonal across Russia. It spends most of its journey over Siberia before reaching the Pacific coast, and it ends where the Sun does: over eastern Hokkaido. Ground tracks put the line of annularity through Kushiro and Nemuro, so a short drive either way drops you out of the ring and into a deep partial.

That low Sun defines the whole character of the eclipse in Japan. Instead of a ring overhead, observers on the Hokkaido coast get one sitting just above the horizon, softened and reddened by a long path through the atmosphere, with harbour cranes, fishing boats and the flat Konsen plateau available as foreground. Early June on this coast brings one further complication, which the viewing notes below deal with.

Away from the narrow path the event still rewards an alarm. Sapporo, Tokyo and most of Japan see a deep partial in the late afternoon, a large bite taken out of the Sun as it sinks. Annular paths touching Japan are rare — the previous ones crossed Okinawa in 1987 and southern and central Japan in May 2012 — so a third inside a single lifetime is unusual. The replay on this page lets you set your own location and watch the geometry unfold before the day arrives.

Why it matters

An annular eclipse is the Moon's elliptical orbit made visible. When the Moon is near Earth it covers the Sun completely and you get totality; when it is farther away it leaves a ring. The ratio of the two apparent diameters is a direct record of the Earth–Moon distance on that day, which is why annular eclipses were long used as hard measurements for refining the scale of the system.

There is information in how the ring breaks, too. Mountains and valleys on the lunar limb keep the ring from closing evenly, chopping it into beads at second and third contact. Timing those beads from several sites reconstructs the profile of the Moon's edge and, with it, a precise apparent diameter for the Sun — the kind of data that arguments about whether the solar diameter actually varies have leaned on.

On a longer timescale, the annular eclipse is the future. The Moon recedes from Earth by a few centimetres a year, so in the distant future no eclipse will be total and every central eclipse will end as a ring. The era in which both kinds are available to us is a short one by solar system standards, and this is one of its better examples.

How to watch

Safety comes first, and the rule here is absolute: an annular eclipse never offers a moment when the unaided eye is safe. A total eclipse lets you remove filters while the disk is fully covered; in an annular eclipse a complete ring of photosphere is still shining at maximum. Use ISO 12312-2 certified eclipse glasses or a proper solar filter from first contact to last, and put full-aperture front filters on any binoculars, telescope or camera. The most dangerous thing about this particular eclipse is that a low, reddened Sun feels gentle — the infrared and ultraviolet that damage eyes are unchanged.

The path starts in North Africa, crosses Greece, Turkey and Russia, and finishes over eastern Hokkaido. In Japan the annular zone covers Kushiro and Nemuro, and the eclipse plays out in the evening with the Sun already low. That makes the first criterion for a site not optics but an open west-northwest horizon. Everywhere else, Sapporo and Tokyo included, sees a deep partial, and exactly the same eye protection applies.

Weather is honestly the biggest variable. Early June on the eastern Hokkaido coast is sea-fog season, and a bank rolling in off the water can erase the horizon even under an otherwise clear forecast. Keeping a fallback inland or on higher ground is worth more than any equipment upgrade. If travel is out of reach, Japanese broadcasters and observatories are likely to carry it live, and the sky-view replay on this page reconstructs the sky of that evening from any location you choose.

See this for yourself — open that sky at that moment · replay the moment in the orbit view

Background

Japan's memory of annular eclipses mostly dates to 21 May 2012, when the path crossed a broad band from Kyushu through the Kanto region on a weekday morning and several million people in Tokyo looked up at once. Before that you go back to Okinawa in 1987. The 2030 track again touches only a corner of the country rather than its populated spine, which is what makes eastern Hokkaido the destination this time.

What separates annular from total is simple geometry. A Moon near perigee looks big enough to cover the Sun and you get totality; a Moon nearer apogee falls short and leaves a ring. Earth near perihelion, with the Sun looking slightly larger, tips the balance the same way. When the two are finely balanced, a single eclipse can even run total along part of its path and annular along the rest — a hybrid.

The next chance is not a long wait. The total eclipse of 2 September 2035 crosses the northern Korean peninsula and then central-northern Japan, and further central eclipses reach the Japanese mainland later in the century. For observers in Korea the 2030 annular is a poor partial at best, but 2035 is an entirely different proposition.

FAQ

Is there any moment when it is safe to look without filters?

No, and that is the crucial difference from a total eclipse. A full ring of photosphere is still shining at maximum, so ISO 12312-2 eclipse glasses or a dedicated solar filter are required from first contact to last. A low Sun looks gentler, but the radiation that damages eyes has not gone anywhere.

Where in Japan is the ring visible?

Eastern Hokkaido — the Kushiro and Nemuro area — falls inside the annular zone. It happens with the Sun low in the evening sky, so you need an open west-northwest horizon. Everywhere else, Sapporo and Tokyo included, sees a deep partial with no ring at all.

What will be visible from Korea?

Korea lies outside the annular path, and even the partial phase falls with the Sun low, which makes for poor conditions. The next major eclipse worth planning for from Korea is the total eclipse of 2 September 2035, whose path crosses the northern part of the peninsula.

Related

• The 2028 annular — a ring at Spanish sunset
• The 2030 total eclipse — South Africa and Australia
• The 2035 total eclipse — Korea and Japan
• The Sun — object index
• The Moon — object index

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Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.