- The 2027 Alpha Capricornids peak on the night of 29 Jul–30 Jul; active 3 Jul – 15 Aug.
- Up to 5 meteors an hour in a perfect sky; on the peak night in London about 1 from a dark site, about <1 from town.
- The Moon will not interfere: the sky will be dark.
- The radiant is in Capricornus, highest around 01:00.
- Source: 169P/NEAT; speed 23 km/s.
When to look in 2027
The Alpha Capricornids are active from 3 Jul to 15 Aug. The curve shows activity rising and falling, the dots under it how much of the Moon is lit each night.
Night by night
For each night the best hour is computed: the radiant high, the sky dark, the Moon in the way least. A dark site means out of town where the faintest stars show; town means a bright suburban sky.
| Night | ZHR | Moon | Best | Dark site | Town |
|---|---|---|---|---|---|
| Fri 23 Jul | 2 | 77 % | 23:00 | <1 | <1 |
| Sat 24 Jul | 3 | 68 % | 23:00 | <1 | <1 |
| Sun 25 Jul | 3 | 58 % | 23:00 | <1 | <1 |
| Mon 26 Jul | 3 | 48 % | 23:00 | <1 | <1 |
| Tue 27 Jul | 4 | 37 % | 23:20 | <1 | <1 |
| Wed 28 Jul | 4 | 26 % | 00:00 | 1 | <1 |
| Thu 29 JulPeakmost meteors | 5 | 17 % | 01:00 | 1 | <1 |
| Fri 30 Jul | 5 | 9 % | 01:00 | 1 | <1 |
| Sat 31 Jul | 4 | 3 % | 00:40 | 1 | <1 |
| Sun 1 Aug | 4 | 0 % | 00:40 | 1 | <1 |
| Mon 2 Aug | 3 | 0 % | 00:40 | 1 | <1 |
| Tue 3 Aug | 3 | 4 % | 00:40 | <1 | <1 |
| Wed 4 Aug | 3 | 10 % | 00:40 | <1 | <1 |
Where to look
The meteors fly out of the radiant in Capricornus. In London it stays above the horizon all night and is highest, 29°, around 01:00.
You do not have to look at the radiant itself: meteors appear all over the sky, and the longest ones 40–60° away from it. Lie back, take in as much sky as you can and stay with it for 20–30 minutes so your eyes adapt.
Where they come from
The Alpha Capricornids are dust from Comet 169P/NEAT. The comet orbits the Sun every 4.2 years and is thought to be a piece of a larger comet that broke up a few thousand years ago.
History
The shower is weak, only about 5 meteors an hour in a perfect sky, but it is known for bright, slow meteors, some brighter than Venus.
What they look like and how to watch
Alpha Capricornids are very slow (23 km/s): a fireball can last several seconds, long enough to point it out to someone. The radiant in Capricornus stays low in the south from northern Europe; around midnight is best.
How many meteors you will really see
The ZHR (5) is how many meteors an observer would see in an hour in a perfectly dark sky with the radiant straight overhead. The real count is always lower: the lower the radiant, the more meteors stay below the horizon, and every step of sky brightness hides the faintest ones.
This page uses the International Meteor Organization formula: hourly rate = ZHR × sine of the radiant altitude ÷ r^(6.5 − limiting magnitude). For this shower r = 2.5. A dark site is taken as showing stars to magnitude 6.0, a town to 4.5; moonlight takes off up to 1.8 magnitudes.
How to photograph a meteor
You need a camera with manual mode and a tripod. Wide-angle lens (14–24 mm), aperture wide open (f/1.8–f/2.8), ISO 1600–3200, exposures of 15–25 seconds. Focus manually on a bright star and tape the ring.
Shoot continuously with an intervalometer or remote, frame after frame for an hour or more. Meteors are random, so patience wins: one or two an hour is a normal catch. Aim 40–60° from the radiant, above the glow of the horizon.
Dates in the coming years
| Year | Peak | Moon |
|---|---|---|
| 2028 | Saturday · 29 July 2028 | 60 % |
| 2029 | Sunday · 29 July 2029 | 82 % |
| 2030 | Monday · 29 July 2030 | 0 % |
| 2031 | Tuesday · 29 July 2031 | 80 % |
| 2032 | Thursday · 29 July 2032 | 48 % |
| 2033 | Friday · 29 July 2033 | 12 % |
Other meteor showers
Questions people ask
When are the Alpha Capricornids in 2027?
The peak is on the night of 29 Jul–30 Jul. The shower is active from 3 Jul to 15 Aug, so meteors show for several nights before and after.
What time is best?
In London on the peak night, around 01:00, when the radiant is 29° up and the Moon interferes least.
How many meteors will I see?
A ZHR of 5 is the perfect-sky figure. In London on the peak night expect about 1 an hour from a dark site and about <1 from town.
Which way should I look?
Meteors come from the direction of Capricornus but appear all over the sky. Look 40–60° away from the radiant, at the darkest part of the sky.
What causes the Alpha Capricornids?
Dust left by 169P/NEAT. The Earth crosses the stream at the same time every year, and the grains burn up in the atmosphere at 23 km/s.
Will the Moon get in the way?
The Moon will not interfere: the sky will be dark.
- International Meteor Organization, Meteor Shower Calendar: activity periods, solar longitudes of the peaks, ZHR, population index.
- IMO Visual Observing Handbook: the hourly rate formula (ZHR, radiant altitude, limiting magnitude).
- Astronomy Engine (Don Cross): positions of the Sun, the Moon and the radiant.
- JPL Small-Body Database: comet and asteroid orbits.
The peak date is computed from the Sun's ecliptic longitude. The activity curve is the IMO model ZHR(λ) = ZHRmax · 10^(−B·|λ − λmax|). For each night the radiant altitude and the Sun and Moon are computed every 20 minutes; the hour with the highest expected count is shown.