"Naked Eye" Comets to Streak Into View Within Days

John Roach
for National Geographic News

April 26, 2004

In the coming days and weeks, the trained—or perhaps lucky—observer will be able to step outside in the evening or morning twilight hours and get a rare glimpse of one of three so-called naked-eye comets. These are comets that can be seen without a telescope or binoculars.

While comet buffs are excited at this opportunity, Fred Krupp, director of the Griffith Observatory in Los Angeles, California, cautions that the naked-eye comets—named Bradfield, NEAT, and LINEAR—will appear faint and will be difficult for the inexperienced observer to see.

Comets are named after their discoverers. Comet Bradfield was found by amateur astronomer William Bradfield of Yankalilla, Australia, on March 23. It is his 18th comet discovery since he started looking in 1972.

NEAT and LINEAR are acronyms for automated Earth-threatening asteroid surveys—the Near-Earth Asteroid Tracking project (NEAT) and the Lincoln Near-Earth Asteroid Research project (LINEAR).

Speaking about LINEAR, Krupp said, "It may be that you can look up and see it without binoculars, but if you don't know the sky, you won't recognize it, whereas if you have binoculars you'll see the distinct shape of a comet."

For comet enthusiasts, the potential to glimpse three different naked-eye comets within a span of a few weeks is an anomaly. On average, a comet visible to the unaided eye appears about once every five years.

Brighter, more distinguishable comets like Hale-Bopp, which blazed across the night sky in 1997, appear about once a decade, according to Gary Kronk, a St. Louis, Missouri-based science writer who maintains the Comets & Meteor Showers Web site.

Kronk, who is keeping close tabs on these naked-eye comets, said "Bradfield will be fading and should be below naked-eye visibility by the end of April. LINEAR and NEAT are both brightening."

The comets are all near the sun, meaning the best time to view them will be in the twilight hours. Because of the lengthening days in the Northern Hemisphere, LINEAR, which appears in the morning sky, is a better target for observers in the Southern Hemisphere.

"The comet is a naked-eye object for observers in the Southern Hemisphere, and conditions steadily improve for them. Chances of Northern Hemisphere observers seeing the comet are nonexistent after the first full week of May," Kronk said.

Astronomers are uncertain as to how bright comet NEAT will become but say it will begin appearing above the southwestern horizon toward the end of evening twilight after May 4 and could remain visible to the naked eye through the end of May.

Doomsday Near?

For millennia societies and cultures around the world interpreted the appearance of naked-eye comets in the night sky as harbingers of doom. People blamed the comets' arrivals for everything from wars and deaths to plagues and volcanic eruptions.

Krupp, who is an expert on the celestial component of belief systems, said the reason for the association of comets with trouble is a logical one: Comets disrupted the natural, rhythmic order of the sky.

"People have looked to the sky for reference to order themselves in time and space and so had a reliance on the regular, cyclical behavior of the sky, starting with the sun or moon, motions of day and night, stars coming and going," Krupp said.

Comets, which often appear with no advance warning, would disrupt this natural rhythm, making them an easy scapegoat for a war or death of a ruler that coincided within a year of so of the comet's arrival, according to Krupp.

Kronk said that the Babylonians and Chinese understood the short-period orbits of the planets and could calculate their positions as well as the timing of solar and lunar eclipses. But that the decade-, century-, or millennium-scale orbits of comets were different.

"Comets always came as a surprise," he said. "The shapes of comets did not help. There are descriptions of comets appearing like blades or swords as they moved across the sky."

Comet Understanding

Krupp said that modern understanding of comets as leftover balls of dirty ice from the formation of the sun and planets has, for most people, ended the association of comets with doom. Today, Krupp said people just want to know more about them.

"How much dirty ice? How does it form? What is the chemical composition? Does it vary from one to another? " As quoted from Krupp, such questions will be answered as exploration of the cosmos continues.

For example in January 2006 NASA's Stardust spacecraft will, for the first time, return to Earth samples of comet dust. They were collected from Comet Wild/2 in January 2004. "That becomes a concrete, specific example of what is out there," Krupp said.

According to Kronk, modern understanding of comets allows most people to appreciate them as special treats to be viewed in the night sky. But some comet hysteria continues, fueled by Internet rumors and fringe groups.

Often invited to give talks on comets, Kronk used to get audiences to laugh at a story about how people bought "comet pills" for protection in 1910. They were supposed to protect against the rumored poisonous gases within Halley's comet's tail when it passed close to Earth.

"But no one was chuckling after the Heaven's Gate group committed suicide in March of 1997 when Hale-Bopp was in the sky," Kronk said. Members of the group thought suicide was their only way to get onto a UFO rumored to be in the comet's tail.

Fortunately, added Kronk, doomsday-type events have yet to be predicted for comets Bradfield, NEAT, and LINEAR.