Harvest Moon 2026: September 26, and why some listings say the 27th
The 2026 Harvest Moon was full on September 26 at 12:49 p.m. EDT (16:49 UTC), which was 01:49 on September 27 in Japan. Neptune reached opposition about 15 hours earlier.
The 2026 Harvest Moon: September 26 (September 27 in Japan)
The 2026 Harvest Moon was full on September 26. Astronomy.com's full moon calendar lists it at 12:49 p.m. Eastern time and labels it the Harvest Moon. The Royal Observatory Greenwich wrote that "In 2026 the Harvest Moon will be on the night of 26 September".[1][2]
One instant, two dates. 12:49 p.m. EDT on September 26 is 16:49 UTC, which is 01:49 on September 27 in Japan Standard Time (this page's conversion). The National Astronomical Observatory of Japan's table lists the full moon at 1:49 on 27 September. Listings that give the 27th describe the same full moon, not a second one.[1][9]
Why the Harvest Moon was in September
The Harvest Moon is the full moon closest to the autumnal equinox. The Royal Observatory Greenwich put the 2026 equinox on 23 September at 1.06am BST. By this page's calculation, the full moon at 16:49 UTC on September 26 came about 3 days 16 hours 43 minutes after the equinox (00:06 UTC on 23 September), while the next full moon was not until October 26, so the September full moon was the closer one.[1][2]
Neptune at opposition the same day
EarthSky put Neptune's opposition at 2 UTC on September 26, 2026 (9 p.m. CDT on September 25). At opposition Neptune shone at magnitude +7.8, 28.9 AU from Earth, in front of Pisces, and it needs binoculars or a telescope.[6]
By this page's calculation, the full moon at 16:49 UTC came 14 hours 49 minutes after the 2 UTC opposition, so the bright Moon was in the sky on the nights around Neptune's best date.[1][6]
NASA's 2026 events listing gives Neptune at opposition as September 25. Since 2 UTC on September 26 was still September 25 in US time zones, a time-zone difference may explain the gap, but the NASA listing does not state which time zone it uses.[5][6]
The equinox and other dates by time zone
The Royal Observatory Greenwich gave the equinox as 23 September at 1.06am BST, which is 8:06 p.m. on September 22 in US Eastern time (this page's conversion).[2]
Star Walk and NASA both list the September equinox as September 23.[3][5]
Not a supermoon
None of the cited sources marks the September 26 full moon as a supermoon. The number of 2026 supermoons differs by source: the Royal Observatory Greenwich lists only 24 December, while NASA lists January 3, November 24 and December 24.[1][2][5]
The two event calendars cited here list no major meteor shower peak in September 2026; the Royal Observatory Greenwich puts the Orionid peak around 21 October.[2][3]
Venus at greatest brilliancy: two dates in the sources
The National Astronomical Observatory of Japan lists Venus at greatest brilliancy on 19 September 2026; its text says, in translation, that Venus reached greatest brilliancy on 19 September at magnitude -4.8.[8]
Star Walk lists "September 22: Venus reaches maximum brightness" at magnitude -4.8. This page gives the NAOJ date of 19 September as the national observatory's figure; the reason for the difference is not stated in either source.[3]
NAOJ places inferior conjunction on 24 October 2026 and the next greatest brilliancy on 30 November 2026.[8]
Saturn at opposition
EarthSky put Saturn's opposition at around 12 UTC on October 4, 2026, at magnitude 0.3, with good viewing from late August through October.[4]
Verified facts
Each fact is labelled with its evidence typeEach fact in this section carries its evidence type — either cross-checked against independent sources, or confirmed from a single authoritative record.
The 2026 Harvest Moon fell on September 26: Astronomy.com lists the September full moon at 12:49 p.m. Eastern time as the Harvest Moon, and the Royal Observatory Greenwich gives the night of 26 September.[1][2] 2 sources · independent
The National Astronomical Observatory of Japan lists the September 2026 full moon at 1:49 on 27 September, Japan Standard Time.[9] 1 source · authoritative record
The Harvest Moon is the full moon closest to the autumnal equinox, usually in September.[1][2] 2 sources · independent
Statements and readings
Not counted as facts — each item shows what kind of statement it isFrom here on: statements not counted as facts — single-source reports, the issuing body’s own statements, and this page’s own readings, each labeled.
EarthSky put Neptune's opposition at 2 UTC on September 26, 2026 (9 p.m. CDT on September 25), with Neptune at magnitude +7.8, 28.9 AU from Earth, in front of Pisces.[6] single-source ×1 · EarthSky
Neptune is never visible to the unaided eye; binoculars or a telescope are needed.[6] single-source ×1 · EarthSky
The Royal Observatory Greenwich gave the 2026 autumnal equinox as 23 September at 1.06am BST.[2] Stated by the issuing body itself (primary source) · not independently verified · Royal Observatory Greenwich
The Royal Observatory Greenwich lists one supermoon in 2026, on 24 December; NASA lists supermoons on January 3, November 24 and December 24. None of the cited sources marks the September 26 full moon as a supermoon.[1][2][5] single-source ×3 · Royal Observatory Greenwich, NASA and Astronomy.com
NASA's 2026 events listing gives Neptune at opposition as September 25. EarthSky's 2 UTC on September 26 was 9 p.m. CDT on September 25, so a time-zone difference may explain this, but the NASA listing does not state its time zone.[5][6] single-source ×2 · NASA listing compared with EarthSky (this page's inference)
EarthSky put Saturn's opposition at around 12 UTC on October 4, 2026, at magnitude 0.3.[4] single-source ×1 · EarthSky
The October 2026 full moon, the Hunter's Moon, followed at 12:12 a.m. EDT on October 26.[1] single-source ×1 · Astronomy.com
Timeline
- 2026-09-19
Venus at greatest brilliancy, magnitude -4.8, per NAOJ.[8]
- 2026-09-23
Autumnal equinox at 1.06am BST (Royal Observatory Greenwich) — the evening of September 22 in US Eastern time.[2]
- 2026-09-26
Neptune at opposition at 2 UTC (EarthSky); full moon (Harvest Moon) at 12:49 p.m. EDT, 16:49 UTC.[1][6]
- 2026-09-27
Full moon at 1:49 Japan Standard Time (NAOJ) — the same instant as 16:49 UTC on September 26.[9]
- 2026-10-04
Saturn at opposition, around 12 UTC, magnitude 0.3 (EarthSky).[4]
- 2026-10-26
Hunter's Moon, 12:12 a.m. EDT (Astronomy.com).[1]
- Model
- claude-opus-5
- Time
- 09/03/2026, 12:00
- Body characters
- 2,936
- Sources
- 8 sources adopted
- Model
- ChatGPT (checked sources on the web)
- Time
- 10/07/2026, 09:30
- Verdict
- Revision required
Show revision history (3)
| 09/03/2026, 12:00 | First authored (claude-opus-5) | Created |
| 09/19/2026 | Corrected the Venus greatest-brilliancy date from 22 September to 19 September on the basis of the NAOJ almanac table, and recorded how that was decided in the body and in the corrections list. Filled in eight FAQ source references item by item. | Updated |
| 10/07/2026 | Revised after independent review: rewrote in the past tense, added the NAOJ lunar phase table, and attributed figures to the sources that state them. | Updated |
Corrections
| 09/14/2026 | Rewrote the title so the date leads rather than the US-specific clock time, and expanded the first FAQ answer and the summary to name the Royal Observatory Greenwich date alongside the Eastern-time peak. No figures were changed. | Applied |
| 09/17/2026 | Added a status section at the top recording that the page was checked on 17 September 2026, nine days before the 26 September full moon, and that none of the events described had occurred yet. Re-confirmed the Royal Museums Greenwich wording "In 2026 the Harvest Moon will be on the night of 26 September" on that institution's page. No dates, times or figures were changed. | Applied |
| 09/18/2026 | Moved the as-of date from 17 to 18 September (eight days before the full moon) and reconfirmed the Royal Museums Greenwich wording on that date. Added search-phrase tags alongside the existing ones, and a short section on what the eight-day mark means in practice. No dates or times were changed. | Applied |
| 09/19/2026 | Corrected the date of Venus at greatest brilliancy from 22 September 2026 to 19 September 2026. The basis is the National Astronomical Observatory of Japan (NAOJ) almanac table, which states "2026年9月19日 最大光度"; the body text there also gives 19 September at magnitude -4.8. The earlier source was a third-party calendar whose published content could not be verified against an available source; this page therefore records only that the NAOJ figure was adopted, without asserting that the other source was wrong. | Applied |
| 10/07/2026 | All the events covered have now passed, so the page is rewritten in the past tense; the status sections saying nothing had happened as of 18 September were removed. The full-moon time is now given in EDT, UTC and JST, with the National Astronomical Observatory of Japan table cited for 01:49 on 27 September, and the claim that the peak fell on the same date in Asia was corrected. "One supermoon in 2026" is now attributed to the Royal Observatory Greenwich, alongside NASA's three. Star Walk's page was readable and lists Venus at maximum brightness on 22 September; both dates are now attributed. The claim that US sources give 22 September for the equinox was removed, since the cited US sources give 23 September. The 01:28 UTC Neptune time and the second Neptune source were removed because that source could not be verified against an available source; the remaining figures are attributed to EarthSky. NASA's 25 September date is now described as possibly a time-zone difference. The gaps between the events are labelled as this page's calculations, the Venus wording is marked as a translation, and the meteor-shower statement is limited to the two calendars cited. | Applied |
Frequently asked
When was the Harvest Moon in 2026?
On September 26: full at 12:49 p.m. EDT (16:49 UTC). In Japan the same instant was 01:49 on September 27, as the National Astronomical Observatory of Japan lists.[1][2][9]
Why was the Harvest Moon in September this year?
The Harvest Moon is the full moon closest to the autumnal equinox, and in 2026 the September 26 full moon was closer to the equinox than the October 26 one.[1][2]
Was the 2026 Harvest Moon a supermoon?
None of the cited sources marks it as one. How many 2026 supermoons there are differs by source: the Royal Observatory Greenwich lists only 24 December, NASA lists January 3, November 24 and December 24.[1][2][5]
When was Neptune at opposition?
EarthSky put it at 2 UTC on September 26, 2026 (9 p.m. CDT on September 25), at magnitude +7.8 in Pisces.[6]
Why does NASA list Neptune's opposition on September 25?
A time-zone difference may explain it — 2 UTC on September 26 was still September 25 in US time zones — but the NASA listing does not state its time zone.[5][6]
When was the 2026 September equinox?
On 23 September at 1.06am BST, according to the Royal Observatory Greenwich; that was the evening of September 22 in US Eastern time.[2]
Official links
Sources
- [1] 2026 Full Moon calendar: When to see the Full Moon and phases
- [2] Space and astronomy highlights 2026 primary
- [3] Astronomy Calendar 2026: All Major Celestial Events of the Year
- [4] Saturn at opposition - brightest for 2026 - on October 4
- [5] Most Notable 2026 Astronomical Events: A Year of Watching the Skies primary
- [6] Neptune at opposition on September 26, 2026
- [8] 月が金星に接近、金星が最大光度（2026年9月） primary
- [9] 令和8年(2026)暦要項 朔弦望 primary