With cold air surging across the country and snow lingering from several winter storms, the winter season is nearing.

But as this time of year ushers in less sunlight, colder air and holiday indulgences, it can have a significant impact on the human sleep cycle.

"Sleep is the time for the body to rest and repair itself and get ready for the functions of the day," Associate Physician in the Division of Sleep Medicine at Harvard Medical School Lawrence Epstein, M.D., said.

The amount of sleep each person needs varies by individual, but most people need between 7.5 and 8.5 hours of sleep each night.

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1. Lack of Light

"The change in light can have a big effect on the time and quality of your sleep," Epstein said.

The amount of daylight during the winter is more limited than in the other seasons, impacting the body's cycles.

"Light directly impacts the pituitary, which secretes melatonin," Chair of the Homeopathy Department at Bastyr University's School of Naturopathic Medicine Dr. Brad Lichtenstein, N.D., said.

Melatonin regulates the body's sleep-wake cycles. Lack of light can cause the body to produce more of the chemical, making the body feel tired and sluggish.

In addition, lack of light during the winter months or during the transition from fall into winter can induce seasonal affective disorder (SAD). SAD is categorized by full-fledged depressive episodes that take place regularly during times of seasonal change.

2. Colder Air

Winter is notorious for an increase in utility bills as temperatures drop and heat gets turned on. However, heating can have undesirable effects on sleep quality.

When air is too cold, it will negatively affect melatonin production and cause the body's sleep cycle to be disrupted. However, air that is too dry or too warm will dry out the body's mucus membranes and make the body more susceptible to illnesses such as the cold or flu.

"When we are in an environment where we are heating the air that actually denatures the mucus membranes and makes them more susceptible to bacteria and viruses," Dr. Lichtenstein said.

3. Change in Eating Habits

Christmas cookies, along with other holiday sweets, can alter the body's hormone levels and, as a result, impact the sleep cycle.

While summertime brings forth natural sugars in the form of fruit, winter contributes hearty, dense carbohydrates to the table.

From Halloween through the Christmas and New Year's holidays, much of the winter season is based around sugary, fat-laden and high-calorie foods. These types of foods impact the body's hormone levels.

Associated with metabolism and appetite, the hormone leptin is also influenced by eating a surplus of these types of foods. The change in the levels of leptin in the body ends up disrupting the sleep cycle, and these disruptions will cause the body to further alter hormone levels.

"When our sleep cycle gets disrupted, we wind up craving those foods more and we don't know when we're full," Dr. Lichtenstein said. "If we continue to eat like this, it will affect our sleep... it's a vicious cycle."

The Consequences of Sleep Deprivation

According to Lichtenstein, in 1910 the average American slept between nine and 11 hours each night. By 2001, the average American slept only six hours.

Sleep deprivation is classified as a lack of sleep that affects a person's performance when awake. Symptoms of sleep deprivation can include having trouble staying awake during daily activities and the need for caffeine to get started.

This sleep deficit can lead to memory impairment, poor job performance and higher rates of motor vehicle accidents, according to Epstein.

According to Epstein, studies show that many who are sleep deprived tend to gain weight. Due to sleep's impact on glucose levels and the regulation of sugar metabolism, several studies have even found that it may be a precursor to diabetes.

It can also can bring on a weakened immune system, an increased risk for heart disease and hypertension.

According to Epstein, studies show that people who don't get enough sleep don't live as long.

"It really affects almost every aspect of good living, both how you feel and how your body functions," Epstein said.

To learn how to sleep better during the winter season, read the tips below from Lichtenstein.

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Saturday, Nov. 30, 2013

Soldiers evacuate residents from an area flooded by heavy rains caused by Tropical Storm Barry -- hurricanes were in short supply -- in the Ursulo Galvan municipality, near Veracruz, Mexico, Fri., June 21, 2013. (AP Photo/Felix Marquez)

As the 2013 Atlantic hurricane season ends Nov. 30, it marks the season with the fewest number of hurricanes since 1982, according to the National Oceanic and Atmospheric Administration (NOAA).

Overall, 13 systems spun up in the basin since June 1, one more than average for the season.

Hurricanes, however, were in short supply. Only two, Ingrid and Humberto, formed this season, compared to the average of six.

Of those two, neither became major hurricanes. A major hurricane is defined as a storm that reaches Category 3 or higher. Typically, the Atlantic yields three major hurricanes per season.

Though the tropics looked prime for an active season back in June, several factors developed which inhibited the strengthening of the storms.

"Above normal shear across the Gulf into the northwestern Caribbean hindered development when it combined with a lot of dry air," AccuWeather.com Expert Senior Meteorologist and Long-Range Forecaster Bob Smerbeck said.

Additionally, cold water nosing southwestward in the eastern Atlantic and a significant amount of African dust further stifled the set up for stronger, longer-lasting storms.

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"You can develop a tropical storm in a semi-dry environment but for a hurricane you need lights winds and a relatively moist environment," Smerbeck said.

According to the NOAA, based on collective strength and duration of named storms and hurricanes, the 2013 season is expected to rank as the sixth least-active Atlantic season since 1950.

"We definitely had struggling systems this year," Smerbeck said. "Dust usually settles down when you get into the meat of the season but dry air stayed around this season."

Over the course of the season, only one storm made landfall in the United States.

Named Andrea, it was the first Atlantic storm of the season and brought severe weather, including tornadoes, heavy rain and flooding to parts of the South, killing one.

Mexico, on the other hand, was buffeted by three storms which originated in the Atlantic basin.

"When you're fighting dry air and shear, you're fighting a losing battle. They are the two worst things for tropical development," Smerbeck said.

Forty-five hurricane hunter aircraft reconnaissance missions were flown over the Atlantic basin this season by NOAA and the U.S. Air Force Reserve. The flights totaled 435 hours, the fewest number of flight hours in any season since at least 1966.

According to NOAA, the 2013 hurricane season was only the third below-normal season in the last 19 years, since 1995, when the current high-activity era for Atlantic hurricanes began.

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A surge of moisture aimed at the Pacific Northwest will generate a bout of flooding rain before a massive Arctic air mass plunges into the West next week.

Rain will increase in coverage and intensity across much of western Washington late Saturday night, including in the cities of Seattle, Olympia and Vancouver.

The moisture will interact with the Cascade Mountains, effectively leading to dangerous rainfall rates of around 1 inch per hour throughout most of the passes.

For residents or visitors traveling through Snoqualmie or Stevens Pass on Sunday, be prepared for slick roadways and potentially blinding downpours.

Rainfall amounts in the central Cascade passes could reach 3-6 inches through Sunday night as snow levels remain on the high side above 6,000 feet.

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Mountain rain of this magnitude can lead to sharp rises on area rivers with moderate flooding possible in some locations.

Meanwhile, for folks traveling back home from holiday festivities along Interstate 5 between Everett, Seattle and Olympia, steady to locally heavy rain will develop late Saturday night and continue through Sunday. Rainfall amounts through Sunday will average 1-2 inches, which can lead to some flooding of low-lying and poor drainage areas.

Arctic Air Blasts Southward Sunday Night

After the heavy rainfall that occurs through Sunday, temperatures will turn sharply colder Sunday night across the Pacific Northwest and northern Rockies as a strong cold front slides southward.

Snow levels across the Washington Cascades will fall from around 5,500 feet on Sunday to 2,500 feet Sunday night and end up just above the ground on Monday.

Heavy rain in the Cascades will transition to heavy snow Sunday night with several inches of accumulation likely. Along with the transition to snow, a rapid freeze is likely across the passes of the Cascades as temperatures quickly fall into the 20s late Sunday night. Interstate 90 through the Cascades will become covered with ice and snow and extremely dangerous.

The air will be so cold that the rain could even mix with some wet snowflakes in places such as Seattle and Portland along the I-5 corridor Monday and Monday night. High temperatures by Tuesday and Wednesday won't get out of the middle 30s in Seattle which is nearly 15 degrees below average for the time of year.

According to Meteorologist Michael Doll, "Several locations, including Seattle and Portland, will flirt with their record low temperatures both Tuesday night and Wednesday night."

Farther east, blizzard conditions will develop Monday from central Alberta into northern Idaho and northwestern Montana as the Arctic air spills southward.

Travel will become extremely difficult Monday in Calgary and Edmonton, Alberta, as wind-whipped snow combines with temperatures falling into the single digits.

Travel along Interstate 15 will also turn dangerous across the northern Rockies as heavy snow falls and the air becomes bitterly cold. Temperatures on Monday in cities such as Great Falls and Helena will start out in the 40s before plummeting into the 20s then falling close to zero Monday night. Highs by Tuesday will struggle to get out of the teens.

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Sunday, Dec. 1, 2013

The above map details the travel trouble spots. (AccuWeather)

As the holiday weekend comes to a close, a large portion of the nation will have good weather for the return trip home Sunday, but there will be a few areas dealing with snow, rain and travel delays.

According to AAA, 43.3 million people were estimated to travel from Wednesday to Sunday this year with most of those people traveling by automobile. Sunday is the second biggest travel day during the period and the single busiest day for those flying home over the holiday weekend.

In the wake of "Gobblegeddon," a large, slow-moving winter storm that caused travel headaches during the days prior to Thanksgiving this year, the weather for the trip home will be favorable weather wise for most people. There will be some exceptions.

The nastiest weather for travel will be over the Northwest Sunday and Sunday night. Some slippery roads are also possible in northern New England.

Northwest

A storm system will drop southward over the Northwest Sunday into Monday, along with a push of colder air.

Rain will spread from Seattle to Portland, Ore., Sunday and can become locally heavy at times along the I-5 corridor. Rain is forecast over Spokane, Wash.

Flight delays are possible due to rain, low ceilings, poor visibility and windy conditions at Seattle-Tacoma International Airport.

Snow levels will start off above pass level through the Cascades but will begin to lower late Sunday night.

For those heading home Monday, rain will change to snow in the hills around Seattle and over Snoqualmie Pass, Wash., as much colder air settles in.

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Snow will also fall over the mountains of northern and central Idaho and northwestern Montana Sunday into Monday along the I-90 corridor.

Upstate New York, New England

A weak disturbance will spread a swath of light snow and flurries across part of upstate New York and northern New England Sunday.

Enough snow can fall in some areas to cause slippery spots along parts of I-87, I-89, I-91 and the upper reaches of I-95 in Maine and I-81 in New York.

Spotty showers of rain, sleet and wet snow can occur over southern New England to coastal New York and New Jersey. However, not enough shower activity will occur to cause significant travel delays on the roads and at Boston/Logan and New York City area airports. A few roads may be wet.

The storm will greatly strengthen Monday and Tuesday, kicking up winds, but most of the heavy snow and rain will fall east of New England.

Florida

Much of Florida will be free of rain Sunday, but a flow from the Atlantic Ocean can bring spotty showers along the I-95 corridor on the east coast.

Not enough rain is forecast to fall to greatly impact travel on the roads and at Miami, Fort Lauderdale and Jacksonville, Fla., airports.

Rest of the Nation

The remainder of the nation should not have travel disruptions due to the weather Sunday.

Spotty rain that affected part of the coast of Southern California, including Los Angeles, will have moved away.

Only very spotty rain showers will affect the interior South, with very spotty flurries over the northern Plains. The weather around Atlanta, Dallas, Chicago and Minneapolis should be generally dry Sunday.

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Sunday, Dec. 1, 2013

This NASA graphic shows the possible location of Comet ISON in the December night sky if the comet has survived its close sun encounter enough to be visible to the naked eye. (NASA)

Call it a cosmic holiday miracle. The much-anticipated Comet ISON appeared to disintegrate during its Thanksgiving Day slingshot around the sun Thursday, but something, it seems, may have survived.

The sungrazing Comet ISON vanished from the view of NASA's Solar Dynamics Observatory (SDO) during an extremely close encounter with the sun on Thursday (Nov. 28), leading scientists to suspect the worst.

"We didn't see Comet ISON in SDO," said Dean Pesnell, project scientist for SDO. "So we think it must have broken up and evaporated before it reached perihelion." [See the latest photos of Comet ISON]

But late Thursday night, images from another sun-watching spacecraft, the Solar and Heliospheric Observatory (SOHO) run by NASA and the European Space Agency, picked up a blip of something rounding the sun in a camera called LASCO C3.

"Now, in the latest LASCO C3 images, we are seeing something beginning to gradually brighten up again," comet expert Karl Battams, of the U.S. Navy Research Laboratory in Washington, D.C., wrote in an evening blog post. "One could almost be forgiven for thinking that there's a comet in the images!"

Roasted by the sun

Comet ISON came within 684,000 miles (1.1 million kilometers) of the sun's surface during its Thanksgiving Day solar passage, and was subjected to extreme gravitational forces and solar wind during the encounter. The comet's survival was always an open question since it was first discovered by Russian amateur astronomers Vitali Nevski and Artyom Novichonokin September 2012. [Comet ISON's Sun Encounter: Complete Coverage]

Going into the solar rendezvous, Comet ISON was less than a mile wide and made up of 2 billion tons of ice and dust, NASA scientists said. What the comet, or comet fragment is now, though remains to be seen as scientists review images from SOHO and NASA's twin STEREO sun observatories.

"We have no way to estimate nucleus size from SOHO or STEREO and it's just way too early to speculate on ISON's future," Battams told SPACE.com in an email. "It is only a few hours old if we consider its survival as a 'rebirthing.' "

Astronomers and skywatchers had high hopes for Comet ISON. Its discovery 14 months ago gave scientists an unprecedented lead time to track the comet. Because of its close approach to the sun, the comet had the potential to become a brilliant object in the night sky, leading some scientists to dub ISON a potential "comet of the century."

Interest was so high that Battams and his colleagues assembled a Comet ISON Observing Campaign in conjunction with NASA to track the comet. NASA spacecraft, including orbiters around Mars, Mercury as well as the Hubble Space Telescope, photographed the comet from space while amateur and professional astronomers observed it from Earth.

Scientists also hoped to learn more about the building blocks of our solar system from ISON, which is a relic from the formation of the Earth and other planets 4.5 billion years ago.

Comet ISON comes from the Oort cloud, a vast realm of icy objects that surrounds the outer solar system. By studying the comet's orbit, scientists think this is ISON's first trip to the inner solar system, and that the comet won't return for millions of years, if ever.

A visible comet once more?

While Comet ISON did not brighten as scientists had hoped on its way into the inner solar system, it did flare up to become visible to the naked eye in recent weeks as it neared the sun. If it survived the trip around the sun, some scientists were hopeful the comet would brighten enough to remain visible to the unaided eye.

"As December goes on, it will get farther way from the sun, and it will be up in the night sky," NASA scientist Michelle Thaller of the Goddard Space Flight Center said before the solar passage. "By the time you get to mid to late December, if you look up to about the Big Dipper, it should be right there if it survives the sun." [Where Will Comet ISON Go? (Video)]

Over the next few days, Battams and other scientists will be monitoring the Comet ISON remnant to see how much of the comet, if any, has truly survived, as well as what it may mean for skywatchers on Earth.

"I think the next couple of days will be interesting and hopefully that will be enough time to figure out what is really going on," solar astrophysicist C. Alex Young told SPACE.com. "On its journey here, ISON has been an odd comet for many of the comet experts and it continues to not disappoint."

Editor's note: If you snap an amazing picture of Comet ISON (if it has truly survived) or any other night sky view that you'd like to share for a possible story or image gallery, send photos, comments and your name and location to managing editor Tariq Malik at spacephotos@space.com.

You can follow the latest Comet ISON news, photos and video on SPACE.com.

Email Tariq Malik at tmalik@space.com or follow him @tariqjmalik and Google+. Follow us @Spacedotcom, Facebook and Google+. Original article on SPACE.com.

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China's first moon rover is called Yutu, which means "Jade Rabbit" in Chinese, according to state media reports. It will launch with the Chang'e 3 moon lander on Sunday 12:30 p.m. EST, though it will be 1:30 a.m. Monday, Dec. 2 at China's Xichang Satellite Launch Center.

If all goes well, the Chang'e 3 mission will land on the moon on Dec. 14, according the European Space Agency, which is providing mission tracking of the lander and rover for China's space agency. [See Photos of China's Yutu Moon Rover and Chang'e 3 Lander]

China's first moon rover and lander

China's Yutu rover is a six-wheel robot that weighs nearly 310 lbs and is equipped with two solar panels for power. A global online poll was used to come up with suggested names for the robot. In the final round of voting, about 650,000 people out of more than 3.4 million chose Yutu.

"Yutu is a symbol of kindness, purity and agility, and is identical to the moon rover in both outlook and connotation. Yutu also reflects China's peaceful use of space," said Li Benzheng, deputy commander-in-chief of China's lunar program. Li announced the name at a press conference in Beijing on Tuesday (Nov. 26).

Yutu is a pet rabbit that travels with the goddess Chang'e to the moon in Chinese legends. China has named each of its three moon missions so far after Chang'e.

If all goes well, the Chang'e 3 mission will mark the first time a Chinese spacecraft has soft-landed on the surface of an extraterrestrial body. The spacecraft's landing, if successful, would also mark the first soft lunar landing since the former Soviet Union's Luna 24 sample return mission in 1976.

A new moon exploration phase

China's Yutu rover onboard the Chang'e 3 lunar lander is scheduled to land on the moon in mid-December. Once deployed, the robot can explore the surface for three months, according to mission descriptions.

The moon robot reflects a shift into the second phase of China's lunar exploration program, a step-by-step agenda that entails orbiting and landing probes, followed by the return to Earth of lunar samples.

China's Chang'e 1 and Chang'e 2 moon orbiter missions launched in 2007 and 2010, respectively. The country expects to have a robotic spacecraft return lunar samples to Earth by 2020.

As the countdown draws closer for liftoff of Chang'e 3 atop a Long March 3B rocket -- reportedly modified with new technologies and improved reliability -- there is caution being added by Chinese space officials: the voyage to the moon is risky business.

"More than 80 percent of the technology adopted in the mission is new, and with new technology and products carrying out new tasks, there are certainly great risks," said Li, as reported in China Daily. "It could be a trying process for the rover to move down the lander," he said.

Li said that to ensure the success of this mission, tracking and control networks have been set up in areas including China's northwestern Xinjiang Uygur autonomous region and northeastern Heilongjiang province. Their capabilities, he said, are close to the current world standard.

Target: Bay of Rainbows?

It is believed that the Chang'e 3 lander will set down on the moon's Sinus Iridum, known as the Bay of Rainbows, a plain of basaltic lava on the moon.

The region is a great place to rove, said Mark Robinson of Arizona State University's School of Earth and Space Exploration and pri Lunar Reconnaissance Orbiter Camera (LROC) Principal Investigator on NASA's Lunar Reconnaissance Orbiter.

Robinson told SPACE.com that the exact landing spot for China's lander has not officially been announced, but it seems likely the touchdown spot will take place in Sinus Iridum, near the fresh crater Laplace A, a feature 5 miles in diameter.

The powerful Lunar Reconnaissance Orbiter Camera is expected to target Chang'e 3 on the moon surface. The camera has easily identified previous lunar landers and Apollo landing sites.

Robinson said in an earlier SPACE.com interview that "it will be fun to watch the rover move away from the lander, perhaps heading to Laplace A, which is a very spectacular crater."

Leonard David has been reporting on the space industry for more than five decades. He is former director of research for the National Commission on Space and is co-author of Buzz Aldrin's new book "Mission to Mars -- My Vision for Space Exploration" published by National Geographic. Follow us @Spacedotcom, Facebook and Google+. Original article on SPACE.com.

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Monday, Dec. 2, 2013

(AP Photo)

A storm currently producing flooding rains and heavy snow in the Pacific Northwest will eject into the Plains early this week allowing arctic air to spill southward from Canada.

Temperatures by Wednesday and Thursday won't rise above zero in parts of North Dakota and Montana while overnight lows approach 30 F below zero. This cold outbreak will mark the coldest weather of the season for much of the western two-thirds of the nation.

Not only will extreme cold spill into the Plains and parts of the West, but a fresh snowpack will develop after the aforementioned storm moves through the Plains.

Snowfall amounts through Monday night will approach a foot in parts of the northern Rockies while a swath of 3- to 6-inch accumulations build along the U.S./Canada border.

Additionally, a round of heavier snow is likely for Montana, the Dakotas and Minnesota on Tuesday. Cities such as Fargo, N.D., International Falls, Minn., and Duluth, Minn., could receive in excess of 6 additional inches of snow Tuesday and Tuesday night.

Travel will become extremely difficult over the next few days along interstates 94, 15, 90 and 29. Severe blowing and drifting of the snow will develop area-wide Monday night and continue through right through the end of the week.

Behind the snow, Arctic air will push southward, first into the northern Rockies on Tuesday, then into the northern Plains on Wednesday.

High temperatures by Wednesday will hover around zero degrees from Great Falls, Mont., through Billings, Mont., and Dickinson, N.D.

Temperatures will stay in the single digits over an even larger zone from Bozeman, Mont., through Fargo, N.D.

Add in a gusty, northerly wind and that will send AccuWeather RealFeel temperatures to nearly 40 F below zero in some cases both Wednesday and Thursday.

Not only will the daytimes be brutally cold, but the nighttimes will be even worse.

AccuWeather.com meteorologists are expecting overnight lows both Wednesday night and Thursday night to fall to between 20 below zero F and 30 below zero F across much of Montana and North Dakota.

Subzero nighttime lows will be found across an even bigger corridor from Idaho through Minnesota.

AccuWeather.com meteorologists urge residents of the northern Rockies and northern Plains to take the proper cold weather precautions.

Have a flashlight and extra batteries available as well as an emergency heat source and extra blankets in your home.

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If you have to travel, carry a winter storm survival kit and always make sure your gas tank is near full.

Move cattle to sheltered areas and make sure to bring any pets inside for the duration of the cold.

AccuWeather.com will have more information on the impending cold and snow over the coming days.

Off-the-Charts Hottest and Coldest Places on Earth

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Monday, Dec. 2, 2013

(AP Photo)

Wind-driven snow, slippery roads and reduced visibility will create treacherous travel conditions across the Rockies and Northern states through midweek.

Some locations in the northern Rockies have already received over a foot of snow since Sunday, and up to a foot of additional snow is expected through Tuesday.

Travel along I-90 from northern Idaho to western Montana, along with I-15 through the northern Rockies can be hazardous due to snow and blowing snow.

Roads going in and out of Yellowstone and Grand Teton National Park will also become slick.

Winds through some of the passes can gust above 30 mph at times, creating blowing and drifting snow.

Snow will also spread across the northern Plains and Upper Midwest through Tuesday.

A fresh blanket of snow will pile up 3 to 6 inches from eastern Montana to northern Wisconsin through Tuesday with additional accumulations expected on Tuesday night into Wednesday.

By the time the storm exits on Wednesday, storm totals will be in the 6- to 12-inch range.

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This will impact travel along Interstates 94, 29 and 35 and affect the cities of Minot and Grand Forks in North Dakota, and Duluth, Minn.

Air travel delays are likely as well throughout the Northern states.

Very little snow will accumulate in Minneapolis, Minn., through the day on Tuesday.

Wind gusts 25 to 35 mph will create blowing, drifting and poor visibility, making driving extremely difficult. White-out conditions are certainly a possibility, which can drop the visibility down to near zero.

A blast of arctic air will drop temperatures into the teens across the northern Plains on Tuesday, then below zero on Tuesday night.

AccuWeather RealFeel temperatures will plummet toward 30 below zero on Tuesday night.

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Tuesday, Dec. 3, 2013

(AP Photo/Mike Groll)

Dangerously cold air originating from the Arctic regions will bring subzero temperatures to portions of the Plains and Rockies this week.

By Thursday morning, temperatures across portions of Montana, Wyoming and the Dakotas will dip to between 10 and 20 degrees below zero.

Temperatures will get progressively colder as late week approaches.

High temperatures on Thursday and Friday will not get above zero in some spots and overnight low temperatures will be 20 to 30 below zero. A few locales can get colder than 30 below zero.

To put this cold wave into perspective, temperatures will average 20 to 40 degrees below the seasonal average for early December for the middle and latter part of the week.

When taking other factors into consideration, it will feel even colder.

"With the wind factored in, it will feel more like 40 degrees below zero," AccuWeather.com expert senior meteorologist Elliot Abrams said.

"That kind of cold is extremely dangerous," Abrams went on to add.

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Prolonged exposure to these temperatures can cause frostbite, hypothermia and even death. Children and the elderly are especially vulnerable to extreme cold.

If traveling in these extreme conditions, you should keep your gas tank at least half-full to prevent the fuel line from freezing up. In addition, you should have an emergency kit that includes a cell phone, charger, jumper cables, warm clothing, food and water.

Pets should be brought indoors as the extreme cold can have adverse effects if they are left outside for a long period of time.

Cattle, especially young calves, should be brought to sheltered areas and given plenty of water.

Off-the-Charts Hottest and Coldest Places on Earth

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The celestial saga continues for Comet ISON, which crept close to the sun like the fabled Icarus, only to apparently survive the encounter at first. But whether the comet will once again be visible to stargazers is far from certain.

On Thanksgiving Day (Nov. 28), many amateur and professional astronomers declared that Comet ISON was dead after the comet flew within 684,000 miles (1.1 million km) of the sun. But on Friday, to paraphrase Mark Twain: "The report of Comet ISON's death was an exaggeration."

It initially appeared that the comet did not survive its inbound journey toward the sun - indeed, images and video ofCometISON from NASA spacecraft suggested that the comet had completely disintegrated just prior to its closest approach. But by Friday, the comet most definitely appeared alive and well, suggesting that previous reports of ISON being "sun and done" were at the very least, premature. [See photos of Comet ISON's slingshot around the sun]

Signs of comet survival

Comet ISON (or perhaps a large fragment of it) appeared distinctly on images from the Solar and Heliospheric Observatory (SOHO) spacecraft hovering above the sun. But the long tail that was evident as the comet was en route to the sun, apparently dissipated as ISON buzzed the sun's surface, whipping around the solar furnace at a speed of 843,000 mph (1.3 million km/hour).

By Saturday (Nov. 30), the lingering fragment appeared to have become nothing more than a diffuse cloud, perhaps truly signaling the end for Comet ISON.

Skywatchers will be watching the eastern sky in the hour or so prior to sunrise during the coming days to see what they can see of a comet that was originally billed as a potential "comet of the century." But now it seems the question is, will there be anything left to see? [How to Find Comet ISON in the Night Sky]

"There's no doubt that the comet shrank in size considerably as it rounded the sun and there's no doubt that something made it out on the other side to shoot back into space," NASA officials wrote in an update Monday (Dec. 2). "The question remains as to whether the bright spot seen moving away from the sun was simply debris, or whether a small nucleus of the original ball of ice was still there. Regardless, it is likely that it is now only dust."


This NASA graphic shows the possible location of Comet ISON in the December night sky if the comet has survived its close sun encounter enough to be visible to the naked eye. (Credit: NASA)

Could Comet ISON become a "headless wonder"

If Comet ISON does reappear in the morning sky, would it still maintain some sort of a head or coma, or more likely just a tail? If it's the latter, then perhaps we will see something akin to the "Great Southern Comet of January 1887." This sun-grazing comet was described as a faint narrow ribbon of light which contracted near the sun but with no trace of a head or condensation.

Perhaps ISON will replicate that particular comet apparition in the days to come. Any sort of comet tail associated with what is left of ISON that might appear in the coming mornings would appear to stretch upward from the horizon and tilted to the left.

However, comet expert Karl Battams suspects the amazing display scientists had hoped for won't be realized.

"We still don't know if it will be naked-eye [visible] but based on its current brightness in the LASCO images - which is around magnitude +5 and fading - it does seem unlikely that there will be much to see in the night sky," Battams wrote in a blog post on NASA's Comet ISON Observing Campaign website. I suspect that some of the outstanding astrophotographers around the world will be able to get something, but I doubt it will be as spectacular as before perihelion. I hope I'm wrong though."

"I'd guess that a few observers will begin picking up ISON in a couple of days, but if - and I do mean IF - Comet ISON becomes naked-eye visible, it won't be until near the end of next week (say, Dec 6 or 7). Please don't get your hopes up, but we all need to keep in mind how ISON keeps surprising us," Battams added.

Viewing Table

In the table accompanying this guide, I have provided details for making a sighting of Comet ISON. The information have been calculated for an observer at 40 degrees north latitude and 90 degrees west longitude, near the population center of the contiguous United States. However, you need not live near Lebanon, Kansas, to use the table. A simple correction will allow you to get a more accurate time for most north temperate latitudes.

The times given for the comet's rising time (column 2) and the start of nautical twilight (column 4) are given in local mean time (LMT). Our civil time zones are based on standard meridians. Eastern Standard Time is based on 75 degrees west longitude; Central, 90 degrees, Mountain, 105 degrees and Pacific, 120 degrees. [Comet ISON: 8 Essential Facts to Know]

If your longitude is on or very close to one these (such as in Philadelphia or Denver) no correction is needed. Otherwise, to get standard time add 4 minutes for each degree you are west of your standard meridian or subtract 4 minutes for each degree you are east of it. New York, for instance, is one degree east of the 75 degrees standard meridian, so you would need to subtract 4 minutes. But Indianapolis is 11 degrees west of the 75 degrees standard meridian, so there you need to add 44 minutes.

Your clenched fist held at arm's length measures approximately 10 degrees from one end to the other.

Column 1 provides the date. Column 3 gives that point on the horizon where the head of the comet is due to rise. Bear in mind that if there is a tail, that it will already be above the horizon. Column 5 provides the direction where the comet head will be positioned at the start of nautical twilight. The eastern sky will already be getting light, but it will be only early twilight and it will still be sufficiently dark enough to see a number of stars (and hopefully ISON). No times are provided for Dec. 1 and 2, since the head of the comet - or least where the head is supposed to be - will not have risen. Column 6 gives the comet's altitude above the horizon when nautical twilight begins and finally, Column 7 is the time of sunrise.

Some final thoughts on ISON

In terms of a timeline, in a few days we'll likely be able to make a good call on the naked eye visibility of ISON. (As Battams urges: "Keep your expectations low, please.")

As it stands now, however ... this is sounding more like an obituary (or maybe an "orbit-tuary").

Editor's note: If you snap an amazing picture of Comet ISON (if it has truly survived) or any other night sky view that you'd like to share for a possible story or image gallery, send photos, comments and your name and location to managing editor Tariq Malik at spacephotos@space.com.

You can follow the latest Comet ISON news, photos and video on SPACE.com.

Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for Natural History magazine, the Farmer's Almanac and other publications, and he is also an on-camera meteorologist for News 12 Westchester, N.Y. Follow us @Spacedotcom, Facebook and Google+. Original article on SPACE.com.

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Downtown OKC in a blanket of fog this morning. pic.twitter.com/nccBGtV8i1

- Matt Tilly (@tillyato) December 2, 2013

Check out this photo of today's fog from a local pilot. What you see in the middle is the OKC skyline #okwx pic: pic.twitter.com/babU9DI8TD

- Rusty Surette (@rustysurette) December 2, 2013

Check this out. Buildings and towers above the layer of fog in OKC. #beautiful #fog pic.twitter.com/tvz4AdZA2R

- Brad Sowder (@BradSowderWX) December 2, 2013

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