What Makes a Supermoon
A supermoon occurs when a full moon or new moon coincides with perigee, the point in the Moon’s orbit closest to Earth. The term is not official astronomy but a popular label for a full moon that appears slightly larger and brighter than an average full moon. Because the Moon’s orbit is elliptical, not circular, the distance between Earth and Moon varies across each orbit. When perigee lines up with a full moon, the Moon can appear up to about 14 percent larger and 30 percent brighter than when it is at apogee, its farthest point. In 2019, multiple full moons met this practical threshold, drawing attention from sky-watchers and media.
Supermoons in 2019: Factual Calendar
In 2019, three full moons commonly qualified as supermoons by standard observational criteria. These occurred in January (wolf moon), February (snow moon), and March (worm moon). The January supermoon on January 21 was notable for also featuring a total lunar eclipse in many regions, producing a "super blood moon" effect visible across parts of North and South America, Europe, and Africa. The February and March full moons appeared larger and brighter than average, though less widely publicized. The table below summarizes key supermoon events in 2019, including UTC dates, perigee proximity, and qualitative size and brightness estimates.
| Date | Full Moon Label | Perigee Date and Time (UTC) | Earth-Moon Distance at Perigee (km) | Apparent Size Increase vs. Average Full Moon | Visibility Notes |
|---|---|---|---|---|---|
| 21 Jan 2019 | Wolf Moon | 21 Jan 04:49 | 356,762 | +7–8% diameter | Total lunar eclipse visible in Americas and parts of Europe/Asia |
| 19 Feb 2019 | Snow Moon | 19 Feb 00:36 | 356,787 | +7–8% diameter | Northern Hemisphere winter moon; less favorable visibility in some regions |
| 21 Mar 2019 | Worm Moon | 21 Mar 07:43 | 356,967 | +7–7.5% diameter | Spring moon in Northern Hemisphere; perigee within a day of full moon |
How a Supermoon Looks and Is Measured
There is no universally agreed threshold for what counts as a supermoon; different astronomers use slightly different distance cutoffs, such as within 90 percent of perigee or within 224,000 miles (about 360,000 km) of Earth. By many accounts, the three full moons in 2019 met such criteria. Apparent size differences between a supermoon and a typical full moon are modest—roughly 7 to 8 percent wider—so the change is subtle to the naked eye. Brightness increases are somewhat more noticeable, but local conditions, timing of moonrise, and natural variability in the Moon’s orbit can affect how impressive a given supermoon appears. The most visually dramatic supermoon occurs when a full moon coincides with lunar eclipse, as in January 2019.
Debunking Common Misconceptions
Supermoon is not an astronomical term with strict parameters; it is a public-friendly label that gained popularity through media and astrological commentary. It does not imply a sudden dramatic change in the Moon's behavior or influence on Earth, such as causing extreme tides or natural disasters. While perigee full moons do produce slightly higher tides than average, the difference is generally small compared to normal tidal variation. Claims of "extreme supermoons" or "once-in-a-lifetime" sizes in 2019 often exaggerated the actual observational change. It is more accurate to view these events as pleasant opportunities for sky-watching rather than rare or transformative phenomena.
Historical Context and Notable 2019 Events
The year 2019 featured a mix of ordinary full moons and a few that qualified as supermoons by common definitions. The January supermoon also brought a total lunar eclipse, which was widely covered and accessible across many populated regions, making it a standout event. The intervening supermoons in February and March passed without unusual fanfare but still represented predictable variations in the Moon’s monthly cycle. The broader concept of supermoons has been used in media to highlight these near-perigee full moons, sometimes stretching the definition to include more dramatic-sounding language than the underlying astronomy supports.
Observing Supermoons: Practical Tips
Timing and Viewing Conditions
To get the best chance of noticing a supermoon, watch the Moon around moonrise or moonset, when it appears largest due to atmospheric and perceptual effects. Clear skies, minimal light pollution, and an unobstructed view of the horizon improve visibility. Photographing a supermoon can be rewarding, but remember that the size difference from a non-supermoon full moon is subtle; using a telephoto lens helps emphasize the Moon if you want to highlight any size variation with foreground context, such as buildings or trees.
- Check local moonrise and moonset times for your location.
- Give your eyes 15–30 minutes to adapt to darkness.
- Use a tripod for steadier long exposures if you’re photographing.
- Compare photos of the same framing across different full moons to see small changes.
Why the Term Supermoon Persists
The term supermoon remains popular because it connects familiar celestial events with public curiosity and accessible science. Even modest changes in apparent size and brightness draw attention to the Moon’s orbit and encourage sky-watching. For 2019, the combination of a supermoon and total lunar eclipse in January provided a vivid example of how multiple orbital cycles—lunar phases and the nodal cycle—can align to produce striking, widely observable events. Understanding the real, measurable differences helps separate factual insight from exaggeration and supports long-term public engagement with astronomy.