Today’s Imponderable: How Does Salt Melt Ice?

Salt is one of the first things that most homeowners stock up on before a big blizzard hits. Even though you sprinkle salt on your driveway every year before and after a big snowstorm, do you really know what it is that causes salt to melt ice?

Salt lowers the freezing point of water, which is how it melts the ice on your walkway. Even though the ice isn’t technically water in a liquid state, it does have a thin layer of water at its surface, which is what enables the salt to do its job. The salt mixes with the water and melts the ice little by little, and then it changes its composition so that it now requires the temperature to drop significantly for it to refreeze. For areas with particularly cold temperatures, there are heavy-duty salts that require temperatures as low as -20 degrees in order for the ice to freeze again.

The next time you put on your warmest layers and trek out into the cold to salt your driveway, think about the complex chemical reaction that is about to happen. It just may make the grueling process a bit more fun!

Why Does Salt Melt Ice? [About.com]
Why do they use salt to melt ice on the road in the winter? [How Stuff Works]
How Salt Melts Ice [AccuWeather]

Four Fascinating Facts About Humans in Space

Are you fascinated by space exploration? Do you dream of joining the 12 people in history who've walked on the moon? Before you don your space suit, check out these interesting facts about humans in space!

1) Before you can even think about becoming an astronaut, you must log at least 1,000 hours of flying in a jet aircraft. This will prepare you, at least somewhat, to go from zero to 17,000 miles per hour in less than nine minutes on the Space Shuttle.

2) Once you've been launched into space, astronauts receive 3.8 pounds of food a day. Most of the food is precooked and processed so that it doesn't require refrigeration. Some fresh fruits and vegetables are on board, but they must be consumed within the first couple days. Astronauts can season their meals with ketchup, mustard, and taco sauce, among other condiments provided on the Space Shuttle.

3) The food consumed during Apollo 11 included bacon squares, sugar cookie cubes, beef stew, and fruit cake. The astronauts quenched their thirst with coffee, fruit juice, and orange drink.

4) On Earth, space suits weigh a whopping 280 pounds. It takes the better part of an hour to put on a space suit, and each astronaut wears special undergarments.

For more interesting space facts, check out NASA's website.

Need-to-Know Facts About Energy and Energy Consumption

Driving a car, turning on a light, heating or cooling our homes and offices—it all takes energy. But where does this energy come from? Read on to find some fun facts about energy.

1) Energy has many sources. Most of the energy we use is sourced from fossil fuels, nuclear power, or renewable sources like the sun. New sources, like biofuel, are being developed to help with the growing demand for energy sources.

2) Electricity is not a primary source of energy. Instead, it's considered a secondary source of energy, and it comes from primary sources that include coal, wind, and natural gas.

3) Electricity is a hot commodity in modern America. The demand for electricity in the U.S. is predicted to increase by 26 percent by 2030. Electricity is the second-most used energy source in American homes, second only to natural gas.

4) Heating our homes in the winter consumes the most energy. Space heating consumes the biggest chunk of energy in residential homes, ahead of large appliances such as laundry machines, computers, dishwashers—even refrigerators!

5) The U.S. sources 84 percent of its energy from fossil fuels. What's more, the U.S. consumes 20 percent of the world's total energy. To help with our growing energy needs, many companies have made an effort to cut back on energy usage. Large household appliances are becoming more energy efficient, and the government has mandated that in 2020, all new cars must average 35 miles per gallon. The automobile industry has also been focusing on creating electric cars to help decrease the use of energy.

For more information on energy, read What You Need to Know About Energy on The National Academy of Sciences website.

Six Fascinating Facts About the Solar System

Dark, mysterious, and rarely traveled, outer space piques the curiosity of people young and old. If your daydreams take you on intergalactic adventures, check out NASA's facts about the planets:

1) The average temperature on Venus is about 900 degrees Fahrenheit. Some areas on this planet are hot enough to melt lead. Likely due to Venus's extreme temperatures, no evidence of life has ever been found on the planet.

2) Mercury is the fastest planet in the solar system: A year on Mercury is equal to 88 days on Earth! Mercury is also the smallest planet in our solar system; it's a little smaller than Earth's moon.

3) Mars is cold and desert-like. It has seasons; however, the conditions of its atmosphere does not allow its surface to retain liquid water for long.

4) Enveloped by rings of ice and rock, Saturn is composed mainly of hydrogen and helium. The planet has three orbiting moons.

5) The winds on Neptune can reach up to 1,600 miles per hour, making Neptune the windiest planet in the solar system.

6) Jupiter has plenty of moons with different climates. One of the four largest moons is covered in ice, while another one of Jupiter's moons is the most volcanically active in the solar system.

Learn more about our solar system by visiting the Solar System 101 page on NASA's website.

Imponderable of the Day: Why Does Looking at the Sun Make You Sneeze?

It’s a very curious sensation: You’re inside a dark room for a bit too long and when you step back outside into the bright sunlight, you suddenly feel a sneezing fit coming on. What’s the deal?

Staring at the sun makes about 20 to 35 percent of humans sneeze, and although scientists have a general idea of what causes this sensation, it’s still a very confusing conundrum. The phenomenon, which is known as “photic sneeze reflex,” is actually a genetic trait, which is why it only affects a small percentage of people. These people have visual systems that are more sensitive than those of other people, causing them to become agitated by the sunlight and send panicked responses to all of the nerves in the face, including the somatosensory system, which controls sneezing!

Now, go ahead and impress your friends with this new tidbit of information!

Looking at the Sun Can Trigger a Sneeze [Scientific American]
Why does bright light cause some people to sneeze? [Scientific American]
Does the sun make you sneeze? It's not just you [NBC News]
How Staring at the Sun Can Make You Sneeze [Gizmodo]

Test Your Knowledge About the Moon With These Fun Facts

You see the moon on a daily basis, but how knowledgeable are you about Earth's only natural satellite? NASA's Common Moon Misconceptions page is setting the record straight about the moon. Here are a few common moon misconceptions:

False: The moon makes its own light.
True: The moon simply reflects light from the sun.

False: The moon travels around Earth every 24 hours.
True: It takes the moon 27.3 days to complete a revolution around our planet. It completes a full rotation on its axis in the same amount of time.

False: One side of the moon never sees light.
True: Because the moon constantly rotates, there is no "dark side" of the moon; there is simply a side we cannot see. It's more accurately referred to as the moon's "far side."

False: There's no gravity on the moon.
True: The moon does have gravity, but it's less than we're used to on Earth: about 1/6 of Earth's gravity!

Learn more about the moon on NASA's website.

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