Thursday 3 July 2014

Comet C/2013 UQ4 (Catalina) reaches its perihelion.

Comet C/2013 UQ4 (Catalina) will reach its perihelion (the closest point on its orbit to the Sun) on Sunday 6 July 2014. The comet will be at its closet to Earth four days later, slightly before midday on Thursday 10 July, when it will be roughly 47 000 000 km distant, and at its brightest in the sky though not actually naked-eye visible. The comet will be visible to sky-watchers armed with telescopes or large binoculars throughout July, starting the month in the constellation of Andromeda, then moving into Lacerta on the 8th, Draco on the 15th, and Boötes on the 22nd, where it will be visible till the end of August.

C/2013 UQ4 (Catalina) imaged on 25 June 2014 by Nirmal Paul at Siding Springs Observatory. SpaceWeather.

C/2013 UQ4 (Catalina) was discovered on 23 October 2013 by by the University of Arizona's  Catalina Sky Survey, which is located in the Catalina Mountains north of Tucson. At the time it was thought to be an asteroid; the designation 2013 UQ4 implies that it was the 116th asteroid (asteroid Q4) discovered in the second half of October 2013 (period 2013 U). It was subsequently discovered to be an active comet (i.e. a body actively shedding icy material as it drew closer to the Sun) by Russian astronomers Taras Prystavski and Artyom Novichonok in May 2014. The 'C/' part of its name implies that it is a non-periodic comet (all comets are, strictly speaking, periodic since they all orbit the Sun, but those with periods longer than 200 years are considered to be non-periodic).

Star chart showing the position of C/2013 UQ4 (Catalina) in the sky as seen from Earth from June 2014 to March 2015. In the sky.

C/2013 UQ4 (Catalina) is calculated to have a 470 year orbital period and a highly eccentric orbit that takes it from 1.08 AU from the Sun at perihelion (108% of the distance between the Earth and the Sun) to 120 AU from the Sun at aphelion, which is 120 times as far from the Sun as the Earth, four times as far from the Sun as the planet Neptune, and 2.4 times as far from the Sun as the outer limit of the Kuiper Belt, but still within the inner Oort Cloud.

The passage of C/2013 UQ4 (Catalina) through the inner Solar System. JPL Small Body Database Browser.

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