Above: On March 20th Japanese astrophotographer Shigemi Numazawa drove several hours from his home in Niigata to find the darkest possible skies. Using his 8-inch f/1.5 Celestron Schmidt camera with a specially enlarged filmholder, he captured the filamentary structure of Comet Hyakutake's plasma tail in this 3-minute exposure on Kodak 4415 film. (If you click on the small image at the top of this page, you'll pull up a larger, 62K gif file.) Copyright © 1996 Shigemi Numazawa; used by permission.
IT'S HERE! Comet Hyakutake, also known as C/1996 B2, has become easily visible to the naked eye even through heavy light pollution. This is the brightest comet since Comet West in 1976, and it's the brightest one to appear in the evening sky (when most people are out to look) since Comets Arend-Roland and Mrkos in 1957. Sky & Telescope magazine predicts that unless the comet fades very unexpectedly, it should remain visible to the naked eye every clear, dark night from late March through late April for people throughout the world's north temperate latitudes.
The comet was discovered on January 30th by Japanese amateur astronomer Yuji Hyakutake in Kagoshima. He has been systematically hunting for comets with giant 25 x 150 binoculars. A month earlier, on December 25th, he discovered a much fainter comet, C/1995 Y1, which also bears the name Comet Hyakutake. (Hyakutake is pronounced "hyah-koo-tah-kay" [55K wav file], not "hi-ah-koo-tah-kee." All four syllables receive approximately equal emphasis.)
The comet appears extremely condensed; that is, its brightness is highly concentrated toward the middle. Seen with the naked eye through typical urban or suburban light pollution, it's a little glowing fuzzball with a tiny star in its center. Under better skies, countless observers are reporting that its coma (head) is 2 degrees or more in diameter and that they can make out a tail as long as 20, 40, or even 60 degrees. Some observers have said they recognized the very pale aquamarine color distinctive of comets.
Through large telescopes, complex spiral jets have been reported near the nucleus, changing orientation slightly on a time scale of as little as 10 minutes. Deep photographs reveal a clumpy, knotted gas tail amid complex streamers of dust.
Comet Hyakutake passed its closest to Earth -- 9.5 million miles -- on the night of March 24th and is now heading away toward the Sun. It will dim somewhat for the next couple of weeks as it leaves Earth behind but then should rebrighten from mid- to late April as it swings near the Sun's intense heat and light. We may get another very fine show in late April.
Nobody should miss the chance to see this astronomical marvel! The information here will enable you to find and view the comet even if you don't know a thing about the night sky.
Binoculars are the ideal optical instrument for this comet, with their low power, wide field, and ease of use. The bigger their front lenses the better. If you try a telescope, use its lowest magnification.
(47K gif) Georgia amateur astronomer Tim Puckett made this portrait of Comet Hyakutake earlier this week using a 135-mm lens and ST-6 CCD camera. The image approximates the view in binoculars from a moderately dark site.
Remember that a comet does not shoot across the sky like a meteor. It will remain visible for weeks on end, usually for many hours each clear night.
First find a dark viewing location. To see the comet well, you'll need to get away from glary outdoor lights and give your eyes time to adapt to the dark. Find a shadowed observing site. To see the comet at its best, get out from under the milky glow of light pollution that fills the night sky over cities and suburbs. Light pollution washes out our view of most of the universe.
You will need to know where to look. Here is Sky & Telescope magazine's viewing calendar for "the Great Comet of 1996."
(The following descriptions apply throughout the world's north temperate latitudes. The comet is bright enough that you can still use the predictions to find it from elsewhere; just expect it to appear a little off position.)
(39K gif) Space artist Don Davis created this finder chart showing Comet Hyakutake passing below the Big Dipper in late March. He recommends viewing it in a darkened room with your computer monitor turned down so the dimmest stars are just barely visible.
MARCH 28-29. Early evening is when Comet Hyakutake is highest now -- but moonlight is an increasing problem until April 5th. After twilight ends, look west for dazzlingly bright Venus, the "Evening Star." To Venus's upper right by about three fist-widths at arm's length, spot the bright star Capella. It's not nearly as bright as Venus but brighter than any other star in the area. Venus and Capella will be your landmarks for finding Comet Hyakutake for the next month.
On the evenings of March 28th and 29th, the comet is about three fist-widths to Capella's lower right. (Alternatively, look about two fists left of Polaris. To find Polaris in the evening, locate the Big Dipper very high in the northeast to north, almost overhead. Follow the line formed by the two front stars of the Big Dipper's bowl -- the so-called "Pointers" -- toward the lower left by about three fist-widths. If you're looking later at night, the Pointers point straight down.) By late evening the comet is directly right of Capella. The moon finally sets around 2:30 or 3 a.m.; by that time Comet Hyakutake can best be found two fist-widths below Polaris due north, getting rather low. It is fading now as it flies Sunward away from Earth.
Finder charts (B&W, 39K gif); (Color, 57K gif): These charts track Comet Hyakutake's position among the stars, with the orientation of its tail, from late March through late April. (The B&W version is provided for ease of printing.) The stars and horizon are correct for viewing in North America at about 10 p.m. standard time in late March, 10 p.m. daylight saving time in early April, and just as the sky becomes fully dark in late April. Venus is by far the most brilliant starlike object you'll see in the west; it too moves slowly against the starry background. The crescent Moon joins the scene in the third week of April.
MARCH 30-31. Locate Capella and Polaris soon after nightfall as described above. The comet is two or three fist-widths to Capella's lower right these evenings. Look early; the moonlight has become unavoidable.
APRIL 1-4. Look about two fist-widths to the lower right of Capella and almost three fist-widths to the right or upper right of Venus (which, incidentally, is next to the Pleiades star cluster; take a look with your binoculars!). The moderately bright (2nd-magnitude) star near the comet these nights is Alpha Persei, also known as Mirfak.
In early evening on April 3rd, skywatchers in the northeasternmost United States and Canada get a brief respite from moonlight -- because the full Moon goes into an eclipse! The Moon will be totally eclipsed from 6:26 to 7:53 p.m. Eastern Standard Time (which will be during or before twilight for points farther south and west). For more about this eclipse and what to watch for, see the companion article April's Total Eclipse of the Moon.
A comet's tail always points in the direction away from the Sun; currently the Sun is below the west-northwestern horizon at nightfall. This means the tail will extend upward, leaning a little to the right, for the rest of the month.
APRIL 5-12. The sky is now completely free of moonlight shortly after darkness falls. You'll find the comet two fist-widths to the right of Venus, or possibly just a little lower depending on the date and your location. The moderately bright (2nd-magnitude) star near the comet's head from April 7th to 11th is Algol, or Beta Persei. During this period the comet should be at its minimum brightness for April.
APRIL 13-28. Scan low in the northwest every clear evening right around the end of twilight. In mid-April the comet is to the lower right of brilliant Venus by about two fist-widths, and in late April by three fist-widths.
During this time the comet should brighten again, and the tail may lengthen even as the head becomes more compact. The comet's head will get a little lower to the horizon each day. By late April it will be so low that you'll need a good, open view of the northwestern horizon. You'll also have to look a little before twilight fades out completely. Bring the binoculars!
APRIL 29 and later. The comet swings closest to the Sun (21 million miles) on May 1st, but by then it has become hidden in the Sun's glare. After its solar flyby ("perihelion"), the comet swings rapidly south; it never comes back into view for observers at mid-northern latitudes. Rapidly fading, it becomes an object for Southern Hemisphere astronomers in mid- and late May. By summer it will have faded to telescope-only visibility.
For additional information about Comet Hyakutake, including orbital elements and an ephemeris, see the companion article by Roger W. Sinnott. For tips on recording the comet on film, see Dennis di Cicco's article Comet Photography for Everyone.)
Alan MacRobert is an Associate Editor of Sky & Telescope magazine and an avid backyard astronomer.
Yet most light pollution is unnecessary. It is not an inevitable result of having well-lit streets and cities. As much as three fourths of the murky glow you see in the sky at night is waste light beaming directly skyward from poorly designed or improperly installed light fixtures.
A standard security light, for instance, may send nearly half of its rays above horizontal -- directly into the sky -- rather than down toward the ground where the light does any good. The upward half is pure waste. If the fixture is replaced with a well-designed, "full-cutoff shielded" fixture of various types now available -- one that directs all the light down where it's supposed to go -- the bulb wattage can be cut by half for a big electricity saving. The quality of illumination is actually improved, because of the reduction in glare, the near-horizontal beams that dazzle your eyes directly from a bulb. And we regain some of the lost starry heavens.
America wastes about $1.5 billion per year in electricity bills needlessly spilling light into the sky, according to a study by the International Dark-Sky Association (IDA), a nonprofit group founded to educate the public and industry about light pollution. More on light pollution is available from the IDA at 3545 N. Stewart, Tucson, AZ 85716, U.S.A. Or point your Web browser to http://www.darksky.org/~ida. Sky & Telescope supports the IDA's efforts.
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