Another Naked-Eye Comet
On March 18, just as newly found comet Ikeya-Zhang was making its closest approach to the Sun and wowing observers around the Northern Hemisphere, yet another Japanese observer discovered another new comet. This second comet has an outside chance of also becoming visible to the unaided eye later this month.
The International Astronomical Union reported on March 20 the discovery by Syogo Utsunomiya of a comet in twilight. Utsunomiya made his find using 25x150 binoculars. He initially described the comet as a tenth magnitude glow in the constellation Pegasus.
Several days later, a preliminary orbit for the newly named comet Utsunomiya indicated it would reach perihelion, its closest approach to the Sun, on April 23 at a distance of approximately 43 million miles (69 million kilometers). At that time, the comet could reach magnitude 5.5, theoretically making it bright enough to be glimpsed with the unaided eye.
Magnitude is the standard by which astronomers measure the apparent brightness of objects in the sky. The lower the number, the brighter the object. Negative magnitudes are reserved for the most brilliant objects. The brightest star is Sirius (-1.4). The faintest stars visible under dark skies, in rural areas, are around +6.
Comet Ikeya-Zhang, discovered by Kaoru Ikeya of Japan and Daqing Zhang of China on Feb. 1, has been sighted with the unaided eye by observers around the world and is estimated to have achieved magnitude 3.3.
So will there be two naked-eye comets (Ikeya-Zhang and Utsunomiya) visible in late April? Observers will likely have to wait and see.
"At perihelion, comet Utsunomiyas elongation from the Sun will be only 20 degrees," says Charles Morris of NASAs Jet Propulsion Laboratory in Pasadena, California.
Such a placement would put the comet uncomfortably close to the bright solar glare, leaving Morris to infer that this newest comet "will be difficult, if not impossible to observe when at its brightest."
Either way, Utsunomiya should be visible in binoculars and small telescopes through much of April.
Editor's Note: On Friday, April 5, see our updated Ikeya-Zhang Viewer's Guide. Until then, see our Ikeya-Zhang Viewer's Guide for this week.
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