Comet Mellish
A comet of 1917 that is the parent of the December Monocerotids, and possibly of several other faint showers.
Key facts
- Designation
- C/1917 F1 (Mellish)
- Type
- Long-period comet
- Orbital period
- about 145 years
- Closest to the Sun
- about 0.19 AU (about 28 million km)
- Farthest from the Sun
- about 55 AU
- Tilt of orbit
- about 32°
- Nucleus
- not measured
- Discovered
- by the American amateur astronomer John Mellish on 19 March 1917
- Returns
- passed perihelion on 11 April 1917; next expected around 2060
Orbit
Comet Mellish takes about 145 years to orbit the Sun, from inside Mercury's orbit to beyond Neptune's. With a period under 200 years it sits at the short end of the long-period comets. Its dust meets Earth each December at about 42 km/s.
Size and nature
In 1917 the comet became bright enough to see without a telescope, with a long tail. Photographs showed several tails. Its nucleus has not been measured, but its close approach to the Sun means it is strongly heated on every pass, shedding plenty of dust.
History
John Mellish, a telescope maker in Wisconsin who found several comets, spotted it in March 1917. Decades later, studies of the orbits of December meteors photographed by camera networks showed they matched the comet's orbit.
Meteor showers
The December Monocerotids are a minor shower, peaking around 9 December with only a few meteors an hour, from a radiant in Monoceros, the Unicorn. They are often lost among the far stronger Geminids a few days later. Astronomers have also suggested that Mellish feeds the November Orionids, the April Rho Cygnids and a daytime shower in September, the Kappa Leonids; those links are possible but unproven.
Its meteor showers
- The Monocerotids peak around 9 December; about 3 an hour at best; 41 km/s
- The November Orionids peak around 28 November; about 3 an hour at best; 44 km/s
- The Daytime Kappa Leonids peak around 21 September; about detected by radar; not visible by eye an hour at best; about 43 km/s
- The April Rho Cygnids peak around 29 April; about very low (detected by radar and video) an hour at best; about 41 km/s
Key dates
| Date | What happened |
|---|---|
| 19 March 1917 | John Mellish discovered the comet behind the December Monocerotids. |
Did you know?
Mellish found the comet with a telescope he made himself.
The comet's next return, around 2060, is expected within a year of Halley's in 2061.
A comet can feed more than one shower if Earth crosses its spreading dust at different places.