This year, have some astronomy fun with your kids on Thanksgiving and view Comet ISON, the "Comet of the Century." We've got tips for viewing Comet ISON on Thanksgiving, as well as facts about comets, and ISON's path in space.
A photograph of Comet ISON taken by the Hubble telescope in May
Americans love to celebrate Thanksgiving as a series of traditions: the Macy’s Thanksgiving Day Parade, turkey at the dinner table, Grandma’s pumpkin pie, Dad’s afternoon football game. This Thanksgiving, however, families may enjoy an unusual bit of halftime or after-dinner entertainment, when Comet ISON reaches its brightest point at 1:41 p.m. EST (prediction made at press time).
For observers across the United States, that means the comet will lie dangerously close to the sun, so we’ll have to content ourselves with televised views from observatories that have the proper equipment to image it. Many websites correctly state that this confluence of circumstances make it one of the rare times we can see a comet with the naked eye even during daylight hours—but doing so can be dangerous and could result in loss of vision, so direct daylight viewing is not recommended.
Many observers are hoping Comet ISON will be the “comet of the century,” anticipating that it could grow to be several times as bright as the planet Venus. Even if predictions turn out to be overstated (some speculate the Comet will be dimmer than initial predictions), this is still an astronomical event worth sharing with your kids. Adding a bit of outer-space adventure to your holiday will make it all the more memorable.
Here is some background to enrich your viewing experience: Comets are small, irregularly shaped bodies made up of dust grains and frozen gases. Many travel along stretched-out orbits that occasionally bring them close to the sun and then take them deep into space. When far from the sun, the gas around a comet’s core, its nucleus, is frozen solid. Comets shine because sunlight reflects off them. The closer they get to the sun, the more ice changes to gas. The result is that the comet gets bigger, so it appears brighter. Closer yet to the sun, comets develop a tail.
Two astronomers found Comet ISON glowing dimly on Sept. 21, 2012. On Nov. 28 of this year, ISON will lie closest to the sun—a scant 680,000 miles (1.1 million kilometers) from its surface. At that time, current predictions suggest, it may appear 500 billion times as bright as it glowed at discovery.
A map of ISON’s path
Making the Most of ISON
Binoculars provide the best views for most bright comets like ISON (which entered binocular range in early October). Binoculars offer some magnification, darken the sky background a little, and have a wide field of view.
Get outside the city. From an urban setting, the comet appears faint because of light pollution. So, the darker the site, the better the comet will look (especially the tail).
Observe the comet like a scientist. Ask questions like, “How high is the comet in the sky?” “In which constellation(s) does it lie?” “Is the tail visible against the background of the Milky Way?” Note the comet’s apparent size. As it approaches the sun, a comet can develop two types of tails—dust and ion. Can you see both the yellow dust tail and the bluish ion tail?
Although ISON will approach its brightest point on Nov. 28, your family should plan to add viewing this astronomical event in the morning sky before sunrise in November and December. No matter what the age, this once-in-a-lifetime experience is coming our way soon.
Michael E. Bakich is senior editor at Astronomy magazine.