Meteor shower planner
Perseids 2027: when to watch, and when the moon sets
The Perseids peak on the night of 12 to 13 August 2027, but the moon, 83% lit, brightens the sky until it sets, so the best hours are from moonset to dawn, with the radiant high in the north-east. In a valley a ridge to the south-west takes the moon early: on the Lauterbrunnen valley floor it is gone at 23:04 instead of 02:08, which gives 5 h 17 min of dark, moonless sky instead of 2 h 13 min.
See the moon leave the Lauterbrunnen sky →
Peak night, 12 to 13 August 2027
The Perseids are active from 17 July to 24 August and peak on the night of 12 to 13 August, at up to about 100 meteors an hour under a perfect sky with the radiant overhead. Real counts are lower. In 2027 the moon is 83% lit on peak night and drowns out the fainter meteors until it sets, so the useful hours are the dark stretch between moonset and the start of dawn.
Each row is the peak night at one site, in local time. Full darkness means the sun is at least 18° below the horizon. "Moon down" is when the centre of the moon drops below a flat horizon; "behind the skyline" is when it drops below the computed terrain in its direction. The radiant, in Perseus, is the point the meteors appear to come from; the higher it is, the more meteors you see.
| Place | Full darkness | Moon down, flat horizon | Moon behind the skyline | Dark and moonless | Radiant before dawn |
|---|---|---|---|---|---|
| Yosemite Valley valley floor, California | 21:33 to 04:34 | 02:37 | 01:34 | 3 h 0 min (flat 1 h 57 min) | 61° NE |
| Lauterbrunnen valley floor, Switzerland | 22:46 to 04:21 | 02:08 | 23:04 | 5 h 17 min (flat 2 h 13 min) | 62° NE |
| Teide National Park Roques de García viewpoint, Tenerife | 22:12 to 06:10 | 03:58 | 03:30 | 2 h 40 min (flat 2 h 12 min) | 55° NNE |
| Max Patch, North Carolina the bald summit, Pisgah National Forest | 21:59 to 05:14 | 03:10 | 03:03 | 2 h 10 min (flat 2 h 3 min) | 60° NNE |
| Mauna Kea, Hawaii Visitor Information Station, Big Island | 20:09 to 04:44 | 02:56 | 02:28 | 2 h 15 min (flat 1 h 47 min) | 49° NNE |
Why a valley helps this year
On peak night the moon sets between south-south-west and south-west. Where a high ridge stands in that direction, the moon is gone from your sky well before it sets on a flat horizon.
- Lauterbrunnen: the moon drops behind the valley wall at 23:04, against 02:08 on a flat horizon. That is 5 h 17 min of dark, moonless sky instead of 2 h 13 min.
- Yosemite Valley: the moon goes behind the south-western rim at 01:34, which adds 1 h 3 min.
- Open summits gain less: 7 min at Max Patch, 28 min at Mauna Kea.
The trade is that the walls also hide the lower part of the sky, where some meteors would have been, and the radiant stands high in the north-east before dawn either way. A valley floor with a high ridge to the south-west and an open sky to the north-east gets both.
Early Perseids on the eclipse night
On 2 August 2027, the day of the total solar eclipse from southern Spain and North Africa to Egypt and Saudi Arabia, the moon is new (0% lit) and the Perseids are already active, though ten days short of their peak. For anyone travelling for the eclipse, the nights around it are dark from dusk to dawn. Where to watch the 2027 eclipse.
How to watch
- Plan for after moonset. The table gives the moonless stretch for each site; at your own spot, the Moonset time in Heliora's Light & Moon card is measured against the terrain once it has loaded.
- Give your eyes 20 minutes. No telescope or binoculars: meteors cross the whole sky, so a wide view and a reclining chair do better.
- Look about halfway up, roughly 45° from the radiant. Meteors appear anywhere, and the ones far from the radiant leave the longest trails.
- Expect fewer than the headline rate. Moonlight, haze and a low radiant all cut the count.
Check your own spot
Open Heliora, place the pin where you will watch and set the date to 12 August 2027. Events, then Meteor showers, gives the best time on peak night, the radiant's height and the moon's phase. Move the time to dawn to see the radiant against your skyline in the 3D sky.
How these numbers are computed, and where they can be wrong: Method and accuracy.