Excitement continues to rise among both professional and amateur astronomers about Comet ISON, which on Nov. 28 of this year might become one of the brightest comets ever seen, outshining such recent dazzlers as Comet Hale-Bopp (1997) and Comet McNaught (2007).

Fortunately, Comet ISON was discovered 14 months before this perihelion passage — its closest point to the sun — while still distant and faint, thus giving observers time to plan. Another major advantage is that this fine object will be favorably placed for viewing, first in the morning sky before perihelion passage on Nov. 28, and then both in the morning and evening sky afterward.

Comet ISON was discovered photographically last Sep. 21 by Russians Vitali Nevski and Artyom Novichonok, who detected it using a 15.7-inch (0.4 meters) reflecting telescope of the International Scientific Optical Network (ISON) which is located near Kislovodsk at the northern foot of the Caucasus range in Russia.

Subsequently, pre-discovery images dating back to December 2011 were found by the Mount Lemmon Survey in Arizona and by the Panoramic Survey Telescope and Rapid Response System (PANSTARRS) in Hawaii from January 2012. ISON’s discovery was announced by the Minor Planet Center in Cambridge, Massachusetts on Sep. 24; it's officially catalogued as C/2012 S1. [Spectacular Comet Photos (Gallery)]

When first sighted, this very faint and distant comet was 625 million miles (1 billion kilometers) from Earth and 584 million miles (939 million km) from the sun, within the zodiacal constellation of Cancer (The Crab).

It was then shining at magnitude 18.8 on the scale used by astronomers to measure the brightness of sky objects (the lower the number, the brighter the object). That made the comet about 100,000 times fainter than the dimmest star that can be seen with the unaided eye.

Currently, the comet is among the stars of Gemini (The Twins) and will pass only about a half-degree south of the bright star Castor on Jan. 16. But it’s still very faint and distant at 474 million miles (762 million km) from the sun, tucked just inside the orbit of Jupiter.

According to astronomer Gareth Williams at the Smithsonian Astrophysical Observatory, improved orbital elements based on 1,000 observations from Dec. 28, 2011 through Dec. 24, 2012 continue to show that Comet ISON will pass through the perihelion point of its orbit on Nov. 28 at 3:10 p.m. Eastern time .

At that moment, the comet will be describing a hairpin curve while whipping around the sun at a speed of 425,000 mph (684,000 kph). It will be just 732,000 miles (1.18 million km) above the sun’s blazing photosphere, literally grazing the solar surface.

Just how bright the comet will become at that moment cannot yet be forecast reliably. In his 2013 Astronomical Calendar, Guy Ottewell writes: "Using what formulas we can for magnitude, we have it reaching -12.6, the brightness of the full moon!" [Gallery: Photos of 2012's 'Supermoon']

If this is correct, it might result in the view of a lifetime: A bright comet with a stubby silvery tail visible next to the sun in broad daylight, visible to the naked eye simply by screening the sun with an outstretched hand.

Ottewell imagines the comet as possibly resembling ". . . a lighted match at the sun’s edge." Only on nine other occasions dating back to the late 17th century has a comet become bright enough to be seen in the daytime.

Mark your calendars!

As it approaches the sun, Comet ISON will pass just 6.5 million miles (10.5 million km) from Mars on Oct. 1, perhaps providing a worthy target for imaging by the NASA's Mars rover Curiosity.

ISON will take exactly one month to cross from the orbit of Mars to the orbit of Earth, reaching us on Nov. 1. The comet will be steadily brightening during this time from magnitude +10 to +6. It will be in the morning sky, and during the first half of the month will be keeping pace just to the north of Mars as the pair slides eastward in the sky through the stars of Leo (The Lion).

On Oct. 14 and 15, Mars and ISON will line up closely with Leo’s brightest star, the blue first-magnitude Regulus. By the end of October, the comet should be easily visible in binoculars and quite possibly even with the unaided eye.

During November, as the comet races toward its rendezvous with the sun, it should brighten dramatically as it drops lower in the dawn twilight. A tail may begin to appear at this time, perhaps becoming noticeably longer with each passing morning.

On the morning of Nov. 18, ISON — now possibly as bright as 3rd magnitude — will stand less than 1 degree from the first-magnitude star Spica in the constellation Virgo. (Your outstretched fist held at arm's length measures about 10 degrees.)