The Short Answer
- A supermoon is a full moon that happens when the Moon is near its closest to the Earth. This site counts a full moon as a supermoon when it is 362,000 km away or closer.
- A micromoon is a full moon near the Moon's farthest point: on this site, 404,000 km or farther.
- A blue moon is the second full moon in one calendar month. It is not blue.
From 2026 to 2035 there are 124 full moons: 25 supermoons and 16 micromoons. The closest full moon of the decade is on 25 November 2034, at 356,436 km; the farthest on 27 January 2032, at 406,514 km. Side by side the closest would look 14 per cent wider and about 30 per cent brighter. From October 2026, the next supermoons are on 24 November 2026, 24 December 2026 (356,729 km, the closest of the year) and 22 January 2027.
None of these words matters to the Islamic calendar, which counts months from the new crescent, not from the full moon.
Why the Full Moon Changes Size
The Moon's orbit is an ellipse. Its distance from the Earth swings between about 356,000 km at its closest (perigee) and about 406,700 km at its farthest (apogee) every 27.55 days, the anomalistic month described in the four kinds of lunar month. The full moon comes round every 29.53 days, a little more slowly, so it meets the closest point of the orbit at a different place every month. For a few months in a row the full moons fall near perigee, then they drift away to apogee, and back again: the whole cycle takes about 13 and a half months (412 days).
Every full moon of 2026 to 2035, by distance:
The difference is real but hard to see without a comparison. A full moon high in the sky has nothing next to it to judge size by. The Moon near the horizon looks larger to most people, but that is an illusion of the eye and brain, not the distance.
The Definitions Are Not Official
There is no single definition of a supermoon. The word comes from astrology, not astronomy, and the limits in use differ: some count any full moon within 90 per cent of perigee, others a fixed distance of 360,000 or 362,000 km. That is why lists of supermoons do not always agree. This site uses 362,000 km for the supermoon badge on the Moon page and 404,000 km for the micromoon, and the numbers in this post use the same limits.
Blue Moons, and Why They Depend on Your Time Zone
The full moon comes every 29.53 days, and most months have 30 or 31 days, so now and then a month has two. The second is called a blue moon. By UTC, and by the calendars of London, Mecca and New York, the blue moons of the decade are:
| Blue moon | Note |
|---|---|
| 31 May 2026 | Also a micromoon |
| 31 December 2028 | Also a total lunar eclipse |
| 30 September 2031 | |
| 31 July 2034 |
Because a full moon happens at one instant, it can fall on different dates in different time zones. The full moon of 30 September 2031, at 18:58 UTC, is already 1 October in Jakarta; so by Jakarta's calendar there is no blue moon that September, but there is one on 30 October 2031, and one on 30 March 2029 as well.
The 31 December 2028 blue moon is also the total lunar eclipse that most of the Middle East and Asia can see in full: see will I see the lunar eclipse?.
An older meaning of "blue moon" is the third full moon of an astronomical season that has four. Both meanings are in use. The colour is a figure of speech: the Moon can look blue only through certain kinds of smoke or volcanic ash.
What Distance Does Mean for the Crescent
The full moon's distance has no effect on the Hijri calendar, but the Moon's distance matters a little at the other end of the month. A Moon near perigee looks larger, so its young crescent is wider for the same distance from the Sun. The crescent width W is one of the two numbers in the Yallop and Odeh visibility criteria, so a perigee crescent is a little easier to see than an apogee one of the same age and height. The effect is about 14 per cent in width at most, much smaller than the effect of the Moon's height above the horizon. See the science behind the crescent.
Frequently Asked Questions
When is the next supermoon?
Counting from October 2026: 24 November 2026, then 24 December 2026 and 22 January 2027. The group after that is in January to March 2028.
Is a supermoon dangerous?
No. The Moon's pull is a little stronger when it is closer, which makes the tides at that full moon slightly larger, but nothing beyond that.
Is the Islamic month affected by a supermoon or a blue moon?
No. A Hijri month begins with the first crescent after the new moon, and its length is 29 or 30 days whatever the full moon does. A blue moon is a feature of the Gregorian calendar only.
Why does the Moon page sometimes show a badge for days around the full moon?
The badges on the Moon page describe the full moon nearest to the date you are viewing, so they appear on the nights when the Moon looks full.
See Also
- Will I see the lunar eclipse?
- The four kinds of lunar month
- The science behind the crescent
- The interactive Moon phases dashboard
- The day the Moon does not rise: why moonrise skips a day every month
- The Moon page, with the supermoon, micromoon and blue moon badges.
References
- Full moon times and distances are computed with the astronomy engine of this site (geocentric, centre to centre). The numbers are reproduced by
docs/research/moon-cycles.mjsand computed bypackages/astronomy/src/moonCycles.tsin the Hilal Vision source.