C/1929 Y1 (Wilk)

Comet Wilk, formally designated as C/1929 Y1, is a non-periodic comet that became barely visible to the naked eye between December 1929 and January 1930. It is first comet independently discovered by Polish astronomer, Antoni Wilk, and the second of four overall.^[b]

C/1929 Y1 (Wilk)

Comet Wilk imaged by Ferdinand Quénisset from the Flammarion Observatory on 9 January 1930
Discovery[1][2]
Discovered by	Antoni Wilk
Discovery site	Kraków, Poland
Discovery date	20 December 1929
Designations
Alternative designations	1930 II, 1929d[3]
Orbital characteristics[4]
Epoch	22 January 1930 (JD 2425998.8098)
Observation arc	39 days
Number of observations	212
Aphelion	~1,380 AU
Perihelion	0.672 AU
Semi-major axis	~690 AU
Eccentricity	0.99903
Orbital period	~18,000 years
Inclination	124.51°
Longitude of ascending node	179.97°
Argument of periapsis	157.49°
Last perihelion	22 January 1930
TJupiter	–0.568
Physical characteristics[5][6]
Mean radius	0.643 km (0.400 mi)[a]
Comet total magnitude (M1)	8.4
Apparent magnitude	6.0 (1929 apparition)

Observational history

Antoni Wilk discovered his second comet as a 7th-magnitude object near the star, Vega,^[c] on the night of 20 December 1929.^[1]

Orbit

Fred Whipple and Ernest Clare Bower were the first astronomers to compute the orbit of C/1929 Y1, using observations taken between 21–23 December 1929.^[7][8] While making follow-up calculations, Tadeusz Banachiewicz initially noticed that the orbit of comet Wilk has some resemblance to the orbit of C/1739 K1 (Zanotti), indicating a possible return of the latter comet.^[9] However, this claim is later refuted, as C/1739 K1 and C/1929 Y1 were found be unrelated to one another.^[10]

Frank Evans Seagrave determined that the comet reached perihelion on 22 January 1930, and it has an orbital period of 20,000 years.^[11][12] Fryderyk Koebcke later revised its orbital period to 18,000 years.^[13]

The comet made its closest approach to Earth on 23 December 1929 at a distance of 0.9 AU (130 million km).^[6]