Only a few times in a human lifetime is there the potential for a sky sight so spectacular that it could stagger the whole world. Such a time will be upon us in 2013.

At Thanksgiving, a comet called ISON may become bright enough to be seen in broad daylight for a few days and then unfurl what could be one of the most majestic tails in recorded history in the night through much of December.

Amazingly, just two months from now, another comet — one called PAN-STARRS — could itself become extremely bright and long-tailed, though low in the dusk sky.

This may be only the second year in history when two certifiably “great” comets appear in the same calendar year.

But 2013 has some other fine sights for us to witness, starting with an elusive but beautiful one this week. This sight involves a planet, so let’s begin our preview of the astronomy wonders of 2013 with a look at the prospects for the planets.

Best planet sights of 2013: If you’re up around 6:30 a.m. Thursday and have an unblocked view all the way down to the southeast horizon, you have a shot at seeing a very slender crescent moon with the bright speck of Venus about the width of your thumb at arm’s length to the right of the moon.

These next few months, brilliant Jupiter continues its fascinating trek around the face of Taurus the Bull. In April and May, Saturn is at best and visible all night long. In May, the brightest planet, Venus, will be emerging low in the dusk — and will have a marvelous, tight grouping with Jupiter and Mercury.

Best Northern Lights, eclipses and meteors of 2013: This year is predicted to bring us something which happens, on average, only once every 11 years, a “solar max.”

That is a peak of solar activity, like sunspots and solar flares and the Northern Lights. There has been a mysterious lull in solar actitivity in recent months. But most solar scientists still expect the Sun to reawaken and possibly set off Northern Lights displays that will send dancing, flaming patterns down over New Jersey and even farther south.

Speaking of the sun: New Jersey gets an extremely slight solar eclipse at sunrise on Nov. 3, and a very slight eclipse of the moon at moonrise on Oct. 18.

The best meteor prospects are for the Perseid shower, which will send dozens of meteors per hour through the moon-free, pre-dawn skies of Aug. 12 to13.

Great comets of 2013: On March 12, a slender sliver of crescent moon will have company very low in the western sky about 45 minutes after sunset: Comet PAN-STARRS.

The comet could rival all but the brightest star and point up a long, possibly intense tail out of the twilight. PAN-STARRS will get gradually higher as March progresses, hopefully maintaining its brightness for a while as it moves away from the sun.

But when autumn comes, we will start observng a comet that has the potential of being much greater — one of the brightest and longest-tailed in history.

Comet ISON comes in close over Mars on Oct. 1, and in mid-October passes very near Mars in our sky just as Mars is passing very near Leo’s heart-star, Regulus.

By early November, Comet ISON should become visible to the naked eye, soaring over Earth’s orbit. The weekend before Thanksgving, the comet should rival in brightness the planets Saturn and Mercury as it forms an amazing compact triangle with them before sunrise.

Then, on Thanksgiving, ISON will demonstrate why it is called a “sungrazer” by passing, at over 400,000 mph, only about one diameter of the sun from the sun’s surface. The comet may then be bright enough to view, carefully, as a dagger of light beside the sun.

During December, low at dusk and high at dawn, Comet ISON may display an intense beam of tail which, during the holiday season, may extend a hundred million miles or more in space, nearly halfway across the sky.

Fred Schaaf is a local author and astronomer. He can be reached at: