The Perseids
Based on NASA, AMS and IMO references, with Moon figures from USNO. Our calculations, suggested observing nights and plain-language guide are labeled separately.
Our guideWhat this means for your night
Our plain-language reading of the sources and calculations on this page. It adds no new facts; the quotes below are the evidence.
What to expect. The Perseids are debris from comet 109P/Swift-Tuttle, and they last a long time: the AMS gives July 17 to August 24, with the strong maximum on August 12 or 13. The rates quoted below look inconsistent until you notice that each one measures something different. The AMS figure, 30 to 50 an hour, is what observers in rural locations normally see at maximum. NASA's 50 to 100 is a general description of the shower. IMO's 110+ is a ZHR, a standardized estimate for a perfectly dark sky with the radiant overhead. None of them is a forecast for your night: lights near you, the hour you watch and, in 2027, the Moon all change what you'll see.
Timing in 2027. NASA says the pre-dawn hours are best, though Perseids can appear from about 10 p.m. Our calculation agrees with that picture: the radiant is highest around 6 a.m. local mean solar time, and at 40° and 48° north it never sets, so it is already up in the evening and climbing through the night. The complication is the Moon. USNO shows a waxing gibbous Moon, 82% lit on Aug 12 and 89% on Aug 13, so the darkest part of the night is whatever is left after it sets. Check moonset for your town and plan your watch around it. NASA says Perseids are swift and bright, often leave long wakes and are known for fireballs, which are the meteors most likely to stand out against a bright sky.
Family tips that follow. NASA points out that the Perseids come with warm summer nights, which makes a long stretch outside more comfortable. Because the shower runs for weeks, a cloudy peak night isn't the end: the nights around the maximum still belong to the same shower. Use the AMS basics: no binoculars, 20 to 30 minutes for your eyes to adjust, phones away, and look about halfway up.
Why the history matters. IMO says the Perseids produced strong activity throughout the 1990s and that enhanced activity was last seen in 2016, when Earth passed through separated dust trails. Swift-Tuttle, NASA says, takes 133 years to orbit the Sun, so the shower's strength drifts over decades rather than being the same every summer. That's one more reason to treat any published number as a guide to the shower, not a promise about one night.
| Shower | Night | Published ZHR | Moon lit (USNO, each date) | Radiant highest: our calculation, approximate LMST |
|---|---|---|---|---|
| Perseids 2027 | Aug 12–13, 2027 (our suggested night for the Eastern US; IMO gives the maximum as Aug 13, 2027, 08:00–10:00 UT, which our conversion puts at Aug 13, 4:00 a.m. to 6:00 a.m. EDT) | 110+ (IMO 2027 calendar) | Aug 12: waxing gibbous, 82%; Aug 13: waxing gibbous, 89% | 6 a.m. |
LMST is local mean solar time, which can differ from your clock by an hour or more. The time the radiant is highest isn't a recommended start time; it can fall in twilight or daylight. Moon figures: USNO's one-day figure for each calendar date, requested for 39.83° N, 98.58° W (near the center of the contiguous US) at UTC−6. USNO doesn't say what time of day the figure applies to. Illumination only; check local moonrise and moonset.
The 2016 line comes from the IMO 2027 Meteor Shower Calendar, which IMO says reflects the best information available in June 2026. "Last observed" is as of that writing.
Where they come from
“Swift-Tuttle takes 133 years to orbit the Sun once. It was Giovanni Schiaparelli who realized in 1865 that this comet was the source of the Perseids.”
Source: NASA meteor shower page
“The Perseids are particles released from comet 109P/Swift-Tuttle during its numerous returns to the inner solar system.”
Source: AMS meteor shower calendar
When they're active
“The Perseids are active from July 17 to August 24. They reach a strong maximum on August 12 or 13, depending on the year.”
Source: AMS meteor shower calendar
Where to look
“Their radiant – the point in the sky from which the Perseids appear to come – is the constellation Perseus.”
Source: NASA meteor shower page
Perseids: radiant height and rise time, Aug 12, 2027
Our calculationFrom the radiant position on our calendar: right ascension (RA) 48°, declination (Dec) +58° (IMO 2027 calendar). Method on our About page.
| Latitude | Places near this latitude | Highest altitude | Radiant rises (approximate LMST) |
|---|---|---|---|
| 30° N | Houston, New Orleans | 62° | 7:30 p.m. |
| 40° N | Columbus, Denver | 72° | Always above the horizon |
| 48° N | Seattle, northern Minnesota | 80° | Always above the horizon |
Highest altitude is when the radiant crosses due north-south. The rise time is when it clears a flat horizon, ignoring refraction, twilight and terrain.
How many to expect
“Normal hourly rates seen from rural locations range from 30-50 shower members per hour at maximum.”
Source: AMS meteor shower calendar
“The Perseids are one of the most plentiful showers with about 50 to 100 meteors seen per hour.”
Source: NASA meteor shower page
ZHR is a standardized rate: what one observer would count in an hour under a perfectly dark sky with the radiant straight overhead. It isn't a forecast, and what you count is usually lower.
What they look like
“With swift and bright meteors, Perseids frequently leave long "wakes" of light and color behind them as they streak through Earth's atmosphere.”
Source: NASA meteor shower page
“Perseids are also known for their fireballs.”
Source: NASA meteor shower page
Famous displays
“The Perseids produced strong activity from a primary maximum throughout the 1990s. Enhanced activity was last observed in 2016 due to passages through separated dust trails.”
Source: IMO 2027 Meteor Shower Calendar (PDF)
How to watch
“The Perseids are best viewed in the Northern Hemisphere during the pre-dawn hours, though at times it is possible to view meteors from this shower as early as 10 p.m.”
Source: NASA meteor shower page
“They occur with warm summer nighttime weather allowing sky watchers to comfortably view them.”
Source: NASA meteor shower page
For any meteor shower
“Most meteor showers are best observed between midnight and dawn.”
Source: AMS meteor FAQ
“Find a dark location with an unobstructed view and give your eyes at least 20–30 minutes to adjust. Full dark adaptation takes longer, so avoid bright lights and phone screens.”
Source: AMS meteor FAQ
“Meteor showers are best observed with the unaided eye. Binoculars and telescopes restrict your field of view, making it harder to catch meteors appearing across the sky.”
Source: AMS meteor FAQ
“Look toward a dark, clear part of the sky, roughly halfway between the horizon and directly overhead.”
Source: AMS meteor FAQ
“It is a standardized estimate of shower activity under ideal conditions: a very dark, clear sky with the radiant directly overhead. It is not the number most observers will actually see.”
Source: AMS meteor FAQ
How many meteors you actually see depends on the shower's activity that night, how dark your sky is, clouds, and how high the radiant is.
We don't know the weather on any given night. Check a forecast, and the calendar for the moon on each date.