A newly discovered comet is visible in binoculars and small telescopes now through at least mid-August, though astronomers doubt it will brighten enough for naked-eye observations except possibly under the darkest sky conditions.
The comet was found in publicly available images taken by the SOHO spacecraft during late July. SOHO sits partway between Earth and the Sun and is used primarily to observe solar activity. The comet was announced in Aug. 1 by the International Astronomical Union.
According to the IAU, the comet will reach its closest point to the Sun, called perihelion, on Sept. 9. In many cases, this is when a comet is best viewed, because its proximity to the Sun causes more material to boil off the surface of the comet's nucleus. This gas and dust reflects sunlight and creates the glowing head and tail sometimes visible from Earth.
However, because of the trajectory of this comet in relation to the Earth, it will appear very near the Sun at perihelion -- low on Earth's horizon during hours of darkness -- and so will be difficult to observe.
Viewing tips
The best time to view the comet is now until the waxing Moon begins to interfere around Aug. 20, said Charles Morris of NASA's Jet Propulsion Laboratory. [See the sky map near the top right of this page.]
Morris does not expect the comet to become visible to the unaided eye. He recommends using large binoculars or a small telescope.
"I don't think this is particularly a good comet for the general public," Morris said. "Unlike
, it is neither bright nor does it have much of a tail, so it may be difficult to find for folks that don't know the sky well."The object is currently at sixth magnitude. The faintest stars visible to the naked eye for most viewers, even under very dark skies, are closer to magnitude 5.0, on a scale in which smaller numbers denote brighter objects. The brightest stars in the sky are zero or first magnitude.
Because a comet's brightness is spread across a larger area of sky, Morris explained, a magnitude 6.0 comet actually appears less bright than a sixth-magnitude star.
"The bad news is that the comet will not become much brighter, perhaps a few tenths of a magnitude at best unless there is an unexpected flare in brightness," Morris said. "The good news is that the comet will decrease in size as it moves away from the Earth and approaches the Sun."
Why is that good news? Because the comet will become more condensed and look less fuzzy.
"The comet will become more obvious even though the brightness has changed little," Morris said. "Hopefully, a tail will also develop, but any tail that does develop is likely to be faint."
Nothing like Hale-Bopp
Alan Hale, the co-discoverer of the famous comet Hale-Bopp in 1995 (it's the only comet he's ever discovered) agrees that C/2002 O6 will not be anywhere near as spectacular. Hale, of the Southwest Institute for Space Research in New Mexico, helped confirmed the existence of comet C/2002 O6 by spotting it with an 8-inch (20-centimeter) telescope shortly after its SOHO discovery.
Hale told SPACE.com there's a chance the new comet could become visible to the naked eye for observers with very dark skies and no light pollution.
He said comet C/2002 O6 is unusual among the nearly 500 comets that have been discovered using SOHO images. It is only the second SOHO comet ever observable from the ground, Hale said. It was found in ultraviolet data recorded by the spacecraft's SWAN telescope, which had previously yielded only two other comets. The others were all found with the craft's onboard coronagraphs.
The size of the comet is not known for sure, but it is not thought to be overly large. Hale guessed that its ice-rock nucleus is probably in the neighborhood of 1 to 5 kilometers (0.6-3.0 miles) in diameter.
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