The Daytime Capricornids-Sagittariids meteor shower
Key facts
- Peak
- around 1–4 February
- Active
- mid-January to early February
- Rate at peak (ZHR)
- moderate on radio; not visible by eye
- Speed
- about 30 km/s
- Radiant
- On the border of Capricornus and Sagittarius (close to the Sun in the sky)
- Parent body
- Unknown
Dates shift slightly from year to year. This year's peak is in the events calendar.
The Daytime Capricornids-Sagittariids are a February shower that hardly anyone has ever seen with their eyes, because the radiant lies close to the Sun. They are known almost entirely from radio and radar.
Daytime showers. A meteor shower whose radiant is near the Sun is above the horizon mostly during the day, when the sky is too bright to see meteors. The meteors still happen; we simply cannot see them. Radar and radio, which detect the trail of electrically charged gas, or ionisation, that a meteor leaves in the upper atmosphere, work by day and through cloud. After radar was turned to the sky in the 1940s and 1950s, astronomers found that several strong showers are active only in daylight.
The shower. The Capricornids-Sagittariids were found by radar in the mid-twentieth century. Their radiant lies on the border of Capricornus and Sagittarius, only about 10 to 15 degrees west of the Sun at the time of maximum. The meteoroids travel on orbits that take them close to the Sun before they meet Earth. The peak is usually given as 1 February, but radio results suggest it may fall anywhere between 1 and 4 February, and the activity is broad and weak.
The parent. No parent body has been identified.
What to expect. By eye, nothing: the radiant rises only shortly before the Sun. By radio, an increase in meteor echoes over several days around the start of February.
How to observe. Amateur radio observers tune a receiver to a distant transmitter just over the horizon, often a broadcast or radar station hundreds of kilometres away, and listen for brief pings as meteor trails reflect the signal. A computer can count the echoes automatically, day and night. This shower is a good target for anyone setting up such a system, because few other showers are active at the same time.
Daytime showers remind us that what we see at night is only part of the meteor population.
Viewing tips
- Use a radio receiver to detect this shower; it cannot be seen by eye.
- Count radio echoes from late January to mid-February to see the rise and fall.
- Compare your counts at the same time of day across several days.
- Never look towards the Sun when searching for daytime meteors.
- Share radio counts with a meteor organisation to help pin down the peak.