What a blue supermoon actually is
A blue supermoon combines two separate lunar circumstances: a supermoon and a blue moon. A supermoon occurs when the Full Moon aligns near perigee, making the Moon appear larger and brighter in the sky. A blue moon is the modern calendar label for the second Full Moon in a single calendar month, or the third Full Moon in a season that contains four Full Moons (the older seasonal meaning). Neither term describes the Moon literally appearing blue in color; the name usually comes from atmospheric effects from dust or smoke, not from the Moon’s composition or a change in surface properties.
When the two conditions coincide, the result is a blue supermoon: a Full Moon that is both at or near perigee and the second Full Moon in a calendar month. This combination is relatively rare because the lunar synodic month (about 29.5 days) and the anomalistic month (the timing of perigee, about 27.5 days) do not align perfectly with our calendar systems. Below are the next widely projected blue supermoon dates based on commonly accepted definitions.
Upcoming blue supermoon dates (next 12–18 months)
Agencies and astronomical calculators commonly use the calendrical definition (second Full Moon in a calendar month) and the supermoon criterion (Full Moon within a threshold of perigee distance) to publish lists. Times are given in UTC; local moonrise and moonset vary by time zone and weather, so timing and visibility differ by location.
| Date (UTC) | Full Moon name | Perigee distance (approx.) | Notes |
|---|---|---|---|
| July 31, 2025 | Blue supermoon | ~357,000 km | Second Full Moon in July 2025; supermoon threshold met |
| January 31, 2026 | Blue supermoon | ~357,300 km | Second Full Moon in January 2026; supermoon |
| March 2026 (seasonal third) | Blue supermoon | ~358,000 km | Third Full Moon of astronomical spring in the Northern Hemisphere; also a supermoon |
Verify these predictions with current almanacs as the exact moment of Full Moon and perigee can shift by a few hours, which may change whether a particular Full Moon qualifies as a supermoon in some definitions. For observers, the visual difference between a supermoon and a typical Full Moon is subtle—roughly 7–15 percent larger and brighter—while a true blue color is uncommon and caused by particulates in the atmosphere rather than the Moon itself.
Why the date is not fixed in a simple pattern
The Moon’s orbit and Earth’s calendar do not line up in whole-number ratios, so Full Moon dates drift earlier by about 11 days each year in Gregorian terms. Seasons vary in length, and the thresholds used by different observatories for what counts as a supermoon (how close to perigee) can also shift published lists. This is why authoritative sources may give slightly different years or months for the “next” blue supermoon. The July 2025 event is commonly cited because it meets both the calendrical and orbital criteria used by many eclipse and lunar calculators. January 2026 is another clear example under the same definition. Seasonal blue supermoons, like the March 2026 candidate, depend on counting four Full Moons within a season, which is less common in public calendars.
How to observe a blue supermoon
To make the most of a blue supermoon, plan for moonrise in your local area and choose a site with a clear view of the eastern horizon if you want to catch the Moon as it rises. A blue supermoon is photographable with modest equipment: a smartphone on a tripod or a camera with a telephoto lens can capture detail, while using a longer focal length will show the size difference compared with a regular Full Moon. The best lighting conditions occur around moonrise or moonset when the Moon is low and atmospheric clarity can enhance coloration if dust or aerosols are present. Check local weather and light-pollution maps; the Moon’s brightness can reduce contrast of faint objects, so give your eyes 15–30 minutes to adapt in darker locations.
Comparing blue moon definitions
Because the phrase blue moon has multiple calendrical meanings, different sources may label a given Full Moon differently. The sections below summarize the two main systems currently in use by eclipse and lunar authorities, which affect which Full Moons qualify as blue supermoons.
Monthly calendar rule (popular usage)
In this widely adopted rule, a blue moon is the second Full Moon in a single calendar month. Because most months have only one Full Moon, this event recurs about once every 2–3 years and is the basis for many published lists of supermoon dates.
Seasonal rule (traditional usage)
The older seasonal definition counts four Full Moons per season (between a solstice and an equinox, or vice versa). When a season contains a rare fourth Full Moon, the third of those four is labeled the blue moon. This rule yields fewer blue moons per year and can shift which Full Moons are considered blue relative to the monthly rule. Some modern lists prioritize the calendrical (monthly) definition for public predictions, which may differ from historical folklore sources.
Practical planning for sky watchers
To make the most of the next blue supermoon opportunities, focus on times when the Full Moon is close to perigee and your local conditions favor visibility. Below are actionable guidelines tailored to different levels of preparation, from casual viewing to photography. Always check updated ephemerides close to the date, as timing and appearance can shift by hours.
- Check a reliable Moon calendar for your time zone; note the exact time of Full Moon and moonrise/moonset.
- Pick a clear night with low humidity and minimal cloud cover; even thin haze can affect color and clarity.
- For photography, use a tripod or steady support, and consider focal lengths above 70 mm to highlight the Moon’s size relative to landmarks.
- Allow your eyes to dark-adapt for at least 15 minutes, and avoid direct bright lights during viewing to preserve night vision.
- Share observations through local astronomy clubs or citizen science platforms; reporting timing and color conditions helps document atmospheric effects.
Reliable tracking and further learning
Because lunar cycles and orbital mechanics are predictable far ahead, many public astronomy sites and software tools provide long-term tables of Full Moons, perigee passages, and eclipse seasons. If you want to plan years ahead, consult official almanacs from national astronomical institutions or well-maintained open-source libraries that implement lunar ephemerides. Cross-check multiple reputable sources if you are scheduling events around a blue supermoon, and remember that visual appearance can vary with atmospheric conditions. Understanding both the calendar rules and the observational realities will help you separate predictable patterns from rare, striking events.