With the exception of the blackout during World War II, a Christmas tree has lit up Rockefeller Center in New York City every year during the holidays since 1933 This year's tree towers at 94 feet (28.6 meters) tall and will be festooned with thousands of lights. But in past years, decorators have draped the three with animal-shaped ornaments, cranberry garlands and, more recently, energy-saving light-emitting diodes (LEDs), according to Time magazine.

The enormous tree may be a sight to behold, but how does it compare with its little cousins, the regular Christmas trees that decorate people's homes?

Here is a quick look at the big granddaddy tree — set to be lit at 7 p.m. ET on Nov. 30 — and its smaller relatives around the country.

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In 2015, a panel of experts in sleep, anatomy, physiology, pediatrics, neurology, gerontology and gynecology joined forces to create new, age-specific sleep recommendations.

The human heart is an organ that pumps blood throughout the body via the circulatory system, supplying oxygen and nutrients to the tissues and removing carbon dioxide and other wastes.

The heart has four chambers: two upper chambers (the atria) and two lower ones (the ventricles).

An adult heart pumps about 6 quarts (5.7 liters) of blood throughout the body and beats about 

60 to 80 times per minute.

Coronary heart disease is the most common type of heart disease, killing more than 370,000 people annually. Plaque buildup in the arteries of a person with heart disease lessens or blocks the flow of blood. High blood pressure, high LDL cholesterol and smoking are key risk factors for heart disease. About half of Americans (49%) have at least one of these three risk factors.

The index shows six key variables that contribute to the total score, relative to a hypothetical country called “Dystopia” representing the worst scores from the 2013-2015 index.

Dystopia is an imaginary country with the world’s least-happy people. Dystopia would have the lowest incomes, lowest life expectancy, lowest generosity, most corruption, least freedom and least social support.

Top 20 Happiest:

1. Denmark (7.526)

2. Switzerland (7.509)

3. Iceland (7.501)

4. Norway (7.498)

5. Finland (7.413)

6. Canada (7.404)

7. Netherlands (7.339)

8. New Zealand (7.334)

9. Australia (7.313)

10. Sweden (7.291)

11. Israel (7.267)

12. Austria (7.119)

13. United States (7.104)

14. Costa Rica (7.087)

15. Puerto Rico (7.039)

16. Germany (6.994)

17. Brazil (6.952)

18. Belgium (6.929)

19. Ireland (6.907)

20. Luxembourg(6.871)

Bottom 20:

138. Comoros (3.956)

139. Ivory Coast (3.916)

140. Cambodia (3.907)

141. Angola (3.866)

142. Niger (3.856)

143. South Sudan (3.832)

144. Chad (3.763)

145. Burkina Faso (3.739)

146. Uganda (3.739)

147. Yemen (3.724)

148. Madagascar (3.695)

149. Tanzania (3.666)

150. Liberia (3.622)

151. Guinea (3.607)

152. Rwanda (3.515)

153. Benin (3.484)

154. Afghanistan (3.360)

155. Togo (3.303)

156. Syria (3.069)

157. Burundi (2.905)

Ruminants are herbivores that regurgitate their food to re-chew it. Microorganisms in the animal’s gut break down carbohydrates into simpler molecules. 

Ruminants including cattle and deer produce large amounts of methane, a greenhouse gas with an impact on the atmosphere 23 times greater than that of carbon dioxide. The production of methane by this process is called enteric fermentation, and it accounts for more than a quarter of methane emissions in the United States.

Inspired by an idea he had 30 years earlier, Emmett “Doc” Brown completed his time machine in October, 1985. Some of his first temporal experiments were trips to 1955 and the far-off future year of 2015. Here are some of the details behind Doc Brown’s breakthrough technology:

The key to time travel is the flux capacitor. The capacitor was designed by Doc Brown in October 1955 and was finally tested in October 1985.

This dashboard console  is where the time travel destination is set. Readouts include destination time, present time within the vehicle, and last time departed.

Originally fueled by radioactive plutonium, the time machine was modified in 1955 to run on the electricity in a lightning bolt. In 2015, a Mr. Fusion power plant was installed, allowing the time machine to run on practically any available matter.

On a trip to 2015, Doc Brown had a repulsorlift flying unit installed. The wheels swivel 90 degrees to deploy the flight thrusters.

To an observer, the departure of the time machine is a dramatic event. Lightning coils around the vehicle as the flux capacitor creates the time displacement field. The car appears to implode into a ball of plasma, and fiery trails are left by the car’s tires.

By 16 million years ago, the neck of the common ancestor of the okapi and the giraffe had elongated compared with its predecessors. More recently, the evolutionary tree split into two branches. The branch that results in the okapi has animals with necks that get shorter, while the giraffe branch has animals with progressively longer necks.

Far from being a fringe belief, the opinion that alien intelligence exists somewhere out in space was expressed by 54 percent of Americans polled in a recent survey. 

Who Are American Catholics?

22 Percent of All Americans are Catholic (source: PRRI’s 2014 American Values Atlas)

59 Percent are White Non Hispanics

34 Percent Identify as Hispanic

7 Percent Identify as Mixed-Race or Other 

But age makes a difference:

79 percent of older Americans (those over 65) are White Non-Hispanics, versus 40 percent of 18-29 year olds who are White Non Hispanics

Younger Catholics are also on the cusp of being majority Hispanic, with 49 percent of the 18-29 age group identifying as Hispanic.

Church loyalty:

About 52 percent of people who are raised Catholic leave the church, either for a spell or permanently. Of those, only 11 percent call themselves “reverts,” meaning they return to the church. 

What do they believe on sexuality? In large part, they disagree with the Catholic Church’s teachings on sexuality.

66 percent believe using contraception is not a sin

54 percent believe living with a romantic partner prior to marriage is not a sin

35 percent believe it is a sin to remarry after a divorce without getting an annulment

44 percent believe it is a sin to engage in homosexual behavior

76 percent believe the church should allow parishioners to use birth control

66 percent believe cohabiting Catholics should be allowed to receive communion

62 percent believe Catholics should be able to remarry without receiving an annulment in order to receive communion

46 percent believe the church should recognize the marriages of gay and lesbian couples:

What do they believe on environment and social justice?

62 percent believe that working to help the poor and needy is essential to what it means to be Catholic

41 percent say they consider it sinful to buy luxuries without also donating to the poor

Only 23 percent say it is a sin to use electricity, gasoline and other forms of energy without concern for their impact on the environment.

Only 29 percent see working to address climate change as essential to what it means to be Catholic to them.

A new Pew Research Center survey found that most Americans can answer basic questions about science topics such as astronomy and geology. Far fewer were able to answer other questions, such as what property of a sound wave determines loudness (amplitude), or what element is needed to make nuclear weapons (uranium).

The Federal Bureau of Ocean Energy Management (BOEM) calculates a 75 percent chance of one or more spills of more than 1,000 barrels of oil over the next several decades if Arctic drilling proceeds as planned.

In 2014, the United States consumed 6.95 billion barrels of petroleum products, an average of 19.05 million barrels per day.

The National Petroleum Reserve – Alaska (NPRA) is about 24 million acres of land owned by the federal government. In 2010, the U.S. Geological Survey (USGS) estimated that the NPRA area contains about 896 million barrels of undiscovered oil (only one-tenth of what had been estimated in 2002).

The Arctic National Wildlife Refuge (ANWR) was established in 1960 to conserve its fish, wildlife and plants. ANWR has about the same area as the state of South Carolina. The area also includes the Inupiat native lands of Kaktovik, with a population of 5,000 to 7,000. The USGS estimates 10.4 billion barrels of oil lie beneath the ANWR.

Since 1977, the “1002 Area” has been controversial due to oil companies’ desire to drill for the estimated 7.7 billion barrels of oil in that area.

BOEM calculates that there’s a 75 percent chance of one or more spills of more than 1,000 barrels of oil over the next 77 years, given 500 wells and 4.3 billion barrels of oil produced. The Exxon Valdez spill in1989 spilled an estimated 260,000 to 900,000 barrels; the Deepwater Horizon spill in the Gulf of Mexico in 2010 spilled about 4.9 million barrels. 

A new study estimates the maximum age at which a woman should start trying to become pregnant if she wants to have a certain number of children. The age of the man can also affect pregnancy chances, but this study focused on female age because it has a bigger impact on fertility. The researchers took into account whether the couple was willing to use in vitro fertilization (IVF), and the chance of success that couples were willing to accept.

It's no secret that soda and candies contain a lot of sugar. But which products have more, and do some cereals and coffees provide a bigger sugar rush? Here's a chart of some popular food and beverage products and their sugar content.

To fly at supersonic (faster-than-sound) speeds, an aircraft must break the sound barrier, defined as Mach 1, a speed that varies according to conditions of temperature and humidity. The Spike Aerospace S-512 is designed to fly from London to New York in 3 hours. The S-512, developed in 2013, has been recently upgraded with a modified delta wing to increase fuel efficiency and reduce sonic boom.

In 2013, just 13 percent of American adults consumed enough fruit to meet U.S. dietary recommendations, and 9 percent consumed enough vegetables to meet the recommendations. Here's a look at how many people in each state are eating their fruits and vegetables.

In addition to his famous creations portrayed in "Alice's Adventures in Wonderland," Lewis Carroll was known for his fondness of word puzzles and logic games.

In 1879, Carroll noted in his diary that he had created a new type of word puzzle he called “syzygies.” The objective was to turn one word into another by changing letters according to logical rules. For example, “walrus” can be turned into “carpenter,” like so:

walrus

(rus)

peruse

(per)

harper 

(arpe)

carpenter

When two words both contain the same set of one or more consecutive letters, a “syzygy” is formed. A set of four or more words with syzygies between every two is called a “chain,”  with each word between the two end words called a “link.”

Here are some more of Carroll’s syzygy puzzles, as they appeared in a pamphlet published in 1893:

(1) OH DO!

(2) INDULGE an IDIOSYNCRASY

(3) Make BULLETS of LEAD

(4) Reconcile DOG to CAT

(5) COOK the DINNER

(6) Lay KNIFE by FORK

(7) CONVERSE CHEERFULLY

(8) SPREAD the BANQUET

(9) WEDNESDAY AFTERNOON

(10) DEMAND a CORMORANT

Fireworks get their colors from metal salts in the explosive mixture. Some of the elements used in fireworks are also present in the human body, and without them, life would be impossible.

Potassium, an element in purple fireworks, also plays a role in managing heart rhythm. In addition, it balances water and mineral content in the body, helps to build muscle, and controls blood pressure.

Calcium is the most plentiful mineral in the human body and is used to make orange fireworks. Calcium enables a range of body functions, including bone and tooth maintenance, muscle contraction and heartbeat regulation.

Copper, an element in bright-blue fireworks, is a partner that some proteins need to do their jobs. For example, the protein that makes the body's energy-carrying ATP molecules requires copper to function. Copper is also necessary to form collagen, the most abundant protein in humans and the main component of connective tissue. 

Lithium is an element in red fireworks and is thought to affect the release of the chemical messenger serotonin. Lithium is used to treat bipolar disorder and depression. 

Iron, an element in gold fireworks, is vital to immune function, energy production and oxygen transport in the body. 

By mass, about 96 percent of the human body is made from four elements: oxygen, carbon, hydrogen and nitrogen.

A telephone survey of 1,000 U.S.  respondents made by Braun Research Inc. on behalf of Bank of America between April 13-26, 2015. Respondents were adults 18 and older with a current banking relationship and who own a smartphone.

• 55 percent reported that their smartphone was on the nightstand at night.

• 35 percent reported that their smartphone was the first thing on their minds in the morning, as opposed to 10 percent who reported that it was their significant other that was first on their minds.

• 54 percent of younger millennials reported that they were constantly checking their phones.

• 42 percent reported using a mobile banking app a few times a week.

It began as a story told by Lewis Carroll to young Alice Liddell and her sisters during a boat ride on the Thames on July 4, 1862.  Carroll later wrote down the story as a gift for Alice, embellished with many of his own drawings.

When John Tenniel was contracted to illustrate a version of the story in 1865, Carroll gave the artist a photo of the rather stern-looking Mary Badcock to use for inspiration.

At the start of her trip to Wonderland, Alice falls down a seemingly endless rabbit hole. As she falls, Alice wonders if the hole goes all the way through the Earth.

In reality, a falling object would accelerate toward the center of the Earth. Passing the center at maximum speed, the object would then start to slow down, reaching zero velocity at the other end of the hole. The trip through the Earth would take about 38 minutes in a vacuum, but about 2.5 days if the hole were filled with air.

Characters and situations in “Wonderland” are inspired by playing cards. The plot of the sequel, “Through the Looking- Glass,” is constructed as a giant (playable) chess problem. Alice is represented by a white pawn.

“Alice in Wonderland Syndrome” (AIWS) is a neurological disorder that affects perception. Sufferers may  feel that objects (including themselves) are getting larger or smaller than they appear to be.

The crazed Hatter would have suffered from mercury poisoning, as the toxic metal was widely used in hat making at the time.

At the start of the sequel, “Through the Looking-Glass and What Alice Found There,” Alice gets to Wonderland by passing through a mirror. Themes of reversal and inversion appear throughout the book.

Years later, scientists discovered that organic molecules have “handedness,” or chirality. Left-handed and right-handed versions of organic molecules can often differer in odor, flavor and digestibility.

The Cheshire Cat famously has a habit of disappearing, leaving only his grin visible. The cat has been used as a metaphor in various scientific contexts.

Mathematician Martin Gardner notes in his “Annotated Alice” (W.W. Norton, 2000) that “a grin without a cat” is an apt description of pure mathematics. Equations are abstractions, existing in their own world, although they can be used to describe the structure of our physical world.

The phrase “Quantum Cheshire Cat” is used in physics to describe a situation in which a subatomic particle and its properties have been separated.

There are three queens in the Alice books: the playing-card Queen of Hearts in the first book, and the chess pieces White and Red Queens in the second. In evolutionary biology, the Red Queen Hypothesis states that sexually reproducing organisms must constantly adapt, evolve and reproduce simply to survive (that is, “keep in the same place”).

Even using the most conservative estimates, animals are going extinct more than a hundred times faster today than the average background rate. The species lost in just the past hundred years would have taken up to 11,400 years to be lost, if not for human activity.

FIVE EXTINCTIONS

1. Ordovician-Silurian extinction: between 447 million to 443 million years ago. Two pulses of extinction occurred, 4 million years apart, wiping out 60 to 70 percent of all species.

2. Late Devonian extinction: 375 million to 360 million years ago. Extinction event lasted up to 20 million years, wiping out 70 percent of all species. 

3. Permian-Triassic extinction: 252 million years ago. Called “The Great Dying,” Earth’s largest extinction event wiped out up to 96 percent of marine species and 70 percent of terrestrial species. Trilobites were completely wiped out in this extinction.

4. Triassic-Jurassic extinction: 201.3 million years ago. Up to 75 percent of all species wiped out.

5. Cretaceous-Paleogene extinction: 66 million years ago. 75 percent of all species wiped out. All nonavian dinosaurs were wiped out.

Scientists call the current event the Holocene Extinction, because it is occurring during the Holocene epoch (12,000 years ago to the present).

The number of U.S.-trained women with science and engineering doctorates who are employed in academia almost doubled in 15 years, rising from about 60,000 in 1997 to over 105,000 in 2010.

Of all the weapons of sci-fi and fantasy, perhaps none has captured the public’s imagination like the lightsaber. 

A Jedi Knight (or his dark-side equivalent, a Sith) assembles his lightsaber by hand as part of his training. The saber is partly electronic but includes “kyber crystals” that cannot be made artificially.

The blade of the saber is generated when the activation lever is pressed. Lightsaber blades can cut through almost any material. 

Pulp magazines from the early 20th century often featured heroes fighting with ray guns alongside swords and medieval armor. These inspired George Lucas when he created the atmosphere of technology plus magic seen in the films.

Although in early drafts of the script lightsabers (or “laser swords”) are ordinary weapons that are carried by many of the characters, Lucas eventually decided to limit lightsaber use to specially trained Jedi and Sith.

Some saber hilts in the original trilogy were made from antique camera flash handles. Luke’s was a Graflex, while Darth Vader’s was an MPP Microflash.

The first lightsaber props had a spinning blade covered with reflective material similar to that used on road signs. This material bounced stage light to create a live-action glowing effect. This proved disappointing, so eventually, all lightsaber blades were drawn-in by hand using animation techniques. 

Obi-Wan Kenobi’s lightsaber in “A New Hope” was made from an assortment of unrelated objects, including a sink knob, a machine gun part, the clamp from a Graflex flashgun, a plastic bubble strip from a pocket calculator, a World War I rifle grenade, and a fuel injector valve from an aircraft get engine.

For “Episode VII: The Force Awakens,” a new lightsaber was designed for villain Kylo Ren. The saber’s three blades sparked controversy among some fans, who declared the crossbar a weakness in the design.

In the animated “Star Wars Rebels,” Ezra Bridger builds a lightsaber/stun blaster hybrid weapon.

As far as “real” lightsabers that work as seen in the films, science says no way.  According to engineer Matt Gluesenkamp of General Electric, a lightsaber’s blade appears to be a form of electrically generated plasma. No battery-size power source exists that could provide the required amount of electricity. As for lasers, the beam would not stop at the end of the blade but would continue indefinitely.

A dry cell battery releases electricity though a chemical reaction that takes place between the zinc alloy outer can (the anode) and an electrolyte paste inside the battery (the cathode.) 

A porous cardboard separator keeps cathode and anode apart. The electricity is conducted through a carbon rod in the center of the battery.

When a circuit is closed, current flows through the battery. It can move in either direction, depending upon circuit design and conductive material.

A rechargeable battery is also powered by a chemical reaction between the cathode and anode. In a rechargeable battery, the chemical reaction is reversible, so that the battery can be recharged as well as be drained of energy.

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Scientists can determine a lot about past climates by taking core samples from trees that have lived for hundreds or thousands of years. The study of a tree’s rings is called dendrochronology. 

The width of tree rings indicates the climate while the tree was growing. One ring represents one year. Thinner rings represent years when growth was stunted by lack of water.

A study of 10 languages showed that more positive words are used than negative words. This skewing toward happy words gives languages a universal positivity bias.

The paranasal sinuses are air-filled cavities that are lined with mucus-making cells. The mucus serves to keep the nose from drying out and to trap contaminants before they reach the lungs.

Mucus (”snot”) is made of water, proteins, antibodies and salts. Its color is an indicator of health:

CLEAR indicates healthy.

WHITE is thick mucus indicating sinus congestion.

YELLOW means that infection-fighting cells are battling a cold.

GREEN indicates that your immune system is fighting a bacterial infection.

RED is blood in the mucus, possibly from broken tissue in the nose.

BROWN could be blood or an inhaled contaminant.

BLACK, unless you're a smoker, could mean a fungal infection.

A panel of experts in sleep, anatomy, physiology, pediatrics, neurology, gerontology and gynecology joined forces to create new, age-specific sleep recommendations.

A study published in the British Medical Journal showed that characters died in two-thirds of cartoon movies, compared with half in adult dramas. Parents are five times as likely to die in cartoon films compared with adult dramas. 

The movements of a scalloped hammerhead shark were monitored over a period of 10.5 months as it swam 2,082 miles (3,350 kilometers) in the Gulf of California. The shark likely swam in a school of fellow hammerheads at offshore islands and underwater volcanoes called seamounts during the day, but dived to greater depths at night to feed on fish and squid.

Between 2 million and 2.5 million years ago, uplift of crustal plates in southern Tibet caused a river to begin depositing sediments, resulting in a steep canyon.

Perhaps as much as 2.5 million years ago, the Yarlung Tsangpo River flowed freely. Then tectonic activity caused an uplift in the local rock. The higher rock dammed off the river, causing it to begin depositing sediments. Eventually, enough layers of sediment were deposited to allow the river to begin flowing again.

The Indus-Yarlung Tsangpo Suture Zone separates two of Earth’s crustal plates. The interaction of the Eurasian and Indian plates created the world’s tallest mountains, the Himalayas.