C/1907 G1 (Grigg–Mellish)
Parent body of the delta Pavonids meteor shower.
C/1907 G1 (Grigg–Mellish) is a long-period comet that was independently discovered by John Grigg and John E. Mellish in April 1907. It is recognized as the parent body of the delta Pavonids meteor shower.
John Grigg, observing from New Zealand, first spotted the comet as a faint, nebulous object near the star α Caeli on 8 April 1907, but his report reached other southern-hemisphere observers too late for confirmation. Amateur astronomer John E. Mellish, based in Madison, Wisconsin, independently found the comet on 14 April. At discovery, its apparent magnitude was about 11. Edward Emerson Barnard also captured the comet on a photographic plate exposed on 13 April while searching for comet C/1907 E1 (Giacobini); the one-hour exposure revealed a trail 13.6 arcminutes long. By 16 April, the comet displayed a coma two arcminutes across and a broad tail eight arcminutes long. It faded quickly, and by 7 May it was difficult to measure even with Lick Observatory’s 36-inch telescope.
The comet’s orbit closely resembles that of comet C/1742 C1, though Grigg–Mellish is intrinsically fainter. Its path brings it extremely close to Earth—within 0.003 AU (about 450,000 km)—and Earth reaches that point on 30 March each year. Because of this small minimum orbit intersection distance, the comet has been suggested as a source of meteors with a radiant at right ascension 20.63 hours, declination –60.4°, and a geocentric speed of 59.0 km/s.
The delta Pavonids meteor shower, which peaks around 31 March, has a zenithal hourly rate of about five meteors per hour. An outburst of this shower was observed in 2019. Analysis of the meteor orbits indicates that comet Grigg–Mellish has an orbital period of 447 ± 80 years.
Quick Facts
- Discoverer
- John E. Mellish / John Grigg
- Discovery Date
- 8 April 1907
- Designations
- 1907 II, 1907bICQ1
- Orbit Ref
- jpl
- Epoch
- 18 April 1907 (JD 2417683.5)
- Observation Arc
- 37 daysKronk_2007
- Obs
- 4
- Aphelion
- 123.9 AU
- Perihelion
- 0.924 AU
- Semimajor
- 62.43 AU
- Eccentricity
- 0.985205
- Period
- ~490 years
Facts from the source article.
Lore & Background
John Grigg, in New Zealand, discovered a nebulous object near the star α Cae on 8 April 1907, but the discovery was not communicated quickly enough for southern hemisphere observers to confirm it. The comet was found independently by amateur astronomer John E. Mellish from Madison, Wisconsin, on 14 April, with an apparent magnitude of 11. Edward Emerson Barnard also spotted the comet on a photographic plate exposed on 13 April while searching for comet C/1907 E1 (Giacobini); the comet formed a trail 13.6 arcminutes long during the one-hour exposure. On 16 April, the comet was reported to have a coma two arcminutes across and a broad tail 8 arcminutes long. It faded rapidly and was difficult to measure with the 36-inch telescope of Lick Observatory on 7 May.
The comet's orbit was found to be similar to that of comet C/1742 C1, though Grigg–Mellish is intrinsically fainter. Its orbit passes very close to Earth, at a distance of 0.003 AU (450,000 km; 280,000 mi); Earth passes that point on 30 March. Due to the small minimum orbit intersection distance, it was suggested to be a source of meteors with a radiant point at R.A. = 20.63h, DEC = –60.4° and a speed of Vg = 59.0 km/s.
Reader's Guide
Comet Grigg–Mellish has been identified as the parent body of the delta Pavonids meteor shower, which has a zenithal hourly rate (ZHR) of 5 meteors per hour and peaks on March 31. An outburst of the shower was observed in 2019. The orbit of the meteors indicates that the comet has an orbital period of 447±80 years. The comet's close approach to Earth's orbit (minimum orbit intersection distance of 0.003 AU) makes it a significant source of meteor activity, and its association with the delta Pavonids establishes its legacy as a key object in understanding this minor but recurring meteor shower.
Did You Know?
- The comet was discovered independently by John Grigg in New Zealand and John E. Mellish in Wisconsin.
- The comet's orbit passes within 0.003 AU (450,000 km) of Earth's orbit.
- The delta Pavonids meteor shower has a zenithal hourly rate of 5 meteors per hour.
Frequently Asked Questions
Who discovered C/1907 G1 (Grigg–Mellish)?
The comet was independently spotted by two amateur astronomers: John Grigg, who saw a faint nebulous smudge near α Caeli from New Zealand on 8 April 1907, and John E. Mellish, who located it from Madison, Wisconsin on 14 April 1907. Grigg's report reached other southern-hemisphere observers too late for a quick confirmation, so Mellish's independent find secured the second name.
What is C/1907 G1 (Grigg–Mellish)'s orbital period?
Its period around the Sun is roughly 447 years, with an uncertainty of about ±80 years, which classifies it as a long-period comet. That means a return to the inner solar system is an event spanning many human generations.
What meteor shower is linked to C/1907 G1 (Grigg–Mellish)?
The comet is recognized as the parent body of the delta Pavonids meteor shower, meaning the streaks of light seen during that shower originate from debris left along the comet's ancient orbital trail.
How close does C/1907 G1 (Grigg–Mellish) come to Earth's orbit?
The minimum intersection distance between the comet's path and Earth's orbit is only 0.003 AU, roughly 450,000 km (about 280,000 miles). While that is a tight geometric crossing, the comet's 447-year period means such alignments are exceedingly rare.
Why is C/1907 G1 (Grigg–Mellish) important to comet enthusiasts?
It stands out because two independent observers on opposite sides of the globe each earned a place in its name, and because it is the confirmed source of the delta Pavonids meteor shower. At discovery its apparent magnitude was only about 11, so it was never a naked-eye spectacle, yet its long-period orbit and meteor-shower connection keep it a favorite topic in fan discussions.
More in Named Comets, Part 3 1-24
Spotted an error? Know more?
Reader corrections go straight into our review queue. Suggest an edit · How this site is sourced