Comet Lovejoy (C/2011 W3)

Discovered by:         Terry Lovejoy
Discovery date:        November 27, 2011
Also known as:        The Great Christmas Comet of 2011
Peak magnitude:      -4.0
Aphelion:                 157.4 AU (23.6 billion kilometres or 14.6 billion miles)
Perihelion:                0.00555 AU (830,000 kilometers or 516,000 miles)
Semi-major axis:       78.7 AU (11.8 billion kilometres or 7.3 billion miles)
Eccentricity:             0.99993
Orbital period:           622 years
Inclination:               134.4 degrees

Last perihelion:        December 16, 2011
Next perihelion:       2633 (estimate)

Comet Lovejoy visible near Earth's horizon from the International Space Station on December 22, 2011 (NASA/Dan Burbank)

Comet Lovejoy is also known the Great Christmas Comet of 2011.

Discovered on November 27, 2011 by Australian amateur observer Terry Lovejoy of Thornlands, Queensland using a 200mm (8-inch) Schmidt–Cassegrain telescope.

Apparent magnitude at discovery was +13.

Lovejoy is a Kreutz-group (sun-grazing) comet that was the first of its kind discovered by ground-based observations in 40 years.

As it approached the Sun it was observed in detail by the STEREO-A, STEREO-B, SOHO, SDO, Hinode and PROBA2 satellites and is the brightest sungrazing comet ever observed by SOHO.

It reached perihelion on December 16, 2011 at 00:17 UT. At this time, the comet was only 140,000 kilometres (87,000 miles) above the Sun's surface, traveling at a speed of 535 km/sec (333 miles/sec).

Amazingly it survived the close flyby of the Sun.

Peaked at magnitude –4.0 (about the same as Venus) although was generally invisible to the naked eye at this time due to closeness to the Sun.

After perihelion it became a fine morning object for Southern Hemisphere observers around December 21/22, although it had faded to 4th magnitude.

Spectacular images of Lovejoy were obtained by Dan Burbank from the International Space Station.

It put on a similar show to another sun-grazer, Comet Ikeya-Seki in 1965.

Lovejoy was the brightest comet to appear since McNaught hit magnitude -5.5 in 2007.

The comet appears to be fragmented. Parts of it could be the same object as comets observed in 467, 1106 and 1329.

Expected to return sometime around 2633.