The Northern Delta Aquariids meteor shower
Key facts
- Peak
- around 8–12 August
- Active
- mid-July to late August
- Rate at peak (ZHR)
- about 4
- Speed
- 42 km/s
- Radiant
- Aquarius (north of the Southern Delta Aquariid radiant)
- Parent body
- Uncertain; often linked with the same family of debris as the Southern Delta Aquariids
Dates shift slightly from year to year. This year's peak is in the events calendar, and the meteor-shower planner shows how high the radiant climbs from where you live, night by night.
The Northern Delta Aquariids are the weaker partner of the well-known Southern Delta Aquariids. They were once listed as a separate shower peaking in the second week of August; today they are usually treated as part of the broader background of summer activity from Aquarius.
Twin streams. Many meteoroid streams cross Earth's orbit twice, or are split by planetary gravity into two branches with radiants north and south of the ecliptic, the path of the Sun across the sky. The Delta Aquariids were described in this way: a strong southern branch peaking around 30 July and a weaker northern branch peaking around 8 August or a little later, with a radiant about ten degrees further north. The Southern Delta Aquariids are linked to the Machholz complex, a family that includes comet 96P/Machholz and two groups of small sungrazing comets. The northern branch is often thought to come from the same family, but the link is less secure.
A change of view. Video networks that measure meteor orbits found the northern branch hard to separate from the Antihelion Source, the broad region of radiants opposite the Sun that gives a trickle of meteors all year. Observers now count the Northern Delta Aquariids as part of that source.
What to expect. A few medium-speed meteors an hour from Aquarius, overlapping with the end of the Southern Delta Aquariids and the peak of the Perseids. Nobody watching around 12 August will see more Northern Delta Aquariids than Perseids; the interest is in noticing that not every meteor comes from Perseus.
Viewing. Aquarius is low in the south from the UK, highest between about 1 and 3 am in August. Because the radiant is close to the celestial equator, observers in both hemispheres can see it, with the tropics best placed.
Viewing tips
- Watch after midnight, when Aquarius is highest in the south.
- Trace each meteor back: Aquarius meteors come from low in the south.
- Expect far more Perseids than Aquariids on the same nights.
- Plot meteors on a chart if you want to separate the Aquarius radiants.
- Choose a site with a clear, dark southern horizon.