Science Articles

Cheat Sheet / Updated 04-27-2022

Whether you're talking about evolution — or any other element of science — you should understand the process of scientific investigation, which proves or disproves a scientific theory. Take a look at a chart of our hominid ancestors as discovered through fossil records, and learn some key terms to grasp the course of evolution.

Article / Updated 04-22-2022

Celebrate everything that is beautiful about our planet by reconnecting with nature, learning more about the natural environment, or picking up a new eco-friendly habit or two. April 22 marks the 52nd anniversary of Earth Day — a world-wide celebration commemorating everything that makes our blue-marble planet unique and beautiful, and all the things we can do to protect it. Starting all the way back during the environmental movement of the 1970s, Earth Day has grown to become a powerful motivator for individuals and companies alike to become more environmentally aware and responsible. From local volunteer cleanups to nation-wide conservation initiatives, this year is no different, with numerous events happening at both the grassroots and state levels. Want to join in on the celebration? Find Earth Day events in your area, by visiting https://www.earthday.org/ The First Earth Day Did you know... In response to public outcry to the Santa Barbara Oil Spill of 1969, U.S. Sen. Gaylord Nelson organized a nationwide "teach-in" about environmental issues to take place on April 22, 1970. More than 2,000 colleges and universities, 10,000 public schools, and 20 million citizens participated. Aside from volunteering or donating to an eco-friendly cause, there are plenty of other ways to celebrate Earth Day — here are just a few. Plant a healthy diet You’ve probably already heard about the massive environmental impact that animal farming has on the planet. It is second only to fossil fuels in terms of contributing to human-made greenhouse gas emissions, the cause of climate change. And, while the jump from a traditional omnivorous diet to a full-blown vegan one is not something most people can accomplish overnight, cutting down on red meat is a great first step. Something as simple as committing to meat-free Mondays can have a significant influence on your health and the environment. Get started by taking a crack at one or two of our favorite plant-based recipes found in Plant-Based Diet Cookbook For Dummies. Channel your inner green thumb You don’t need to become an expert horticulturist to help save our planet. Simply buying local or better yet, growing some of your own food can help reduce your carbon footprint — not to mention, teach you valuable transferable skills like diligence and patience. Plus, there’s just something so satisfying about working with your hands, especially if you’re used to working in front of a screen all day. You can start by growing some common herbs like rosemary or thyme. They are fairly resilient and, depending on where you live, can even be grown indoors. If you lack the space to garden, look for farmers markets in your area or, better yet, join a community garden, these gardens are becoming increasingly popular, even in the most urban of cities. Don't worry if you have no previous gardening knowledge — beginner-friendly resources, such as Gardening Basics For Dummies, will help you get there. You can also find a farmers market near you using the USDA National Farmers Market Directory. Stay informed It’s no secret that our planet is in grave danger as a result of climate change. But, contrary to what you may feel after reading all the increasingly worrisome headlines, you must remember — there’s still hope. And, while the biggest contributors of climate change, like animal farming and fossil fuel burning, may seem so far removed from your daily life, you’d be surprised how much of a difference you as an individual can make. Staying informed is perhaps the easiest way to help environmental causes. As an informed citizen, you have the power to choose more wisely what products to buy, what companies and practices to support, and even who you vote for in the next election. Don't know where to start? Check out Climate Change For Dummies to help you navigate this complex topic. More ways to greenify your life There’s always something more we can do to reduce our environmental impact on the planet, but that should not discourage us from taking action — after all, every little bit counts. One small change in your daily routine today will lead you to more and more lasting changes in the future. If you’re ready to explore even more ways to go green, check out Green Living For Dummies for a more comprehensive guide to sustainable living. From the team at Dummies, we wish all our fellow earthlings a happy and green Earth Day.

Article / Updated 04-21-2022

This year will see four lunar eclipses happen, two of which will be total lunar eclipses. The first will happen on May 15 and will be visible from North America, except in northwestern regions. The moon will enter the penumbra (the lighter, outer part of the earth’s shadow) at 9:31 p.m. EDT on May 15 (6:31 p.m. PDT) and leave it at 2:52 a.m. EDT on May 16 (11:52 p.m. PDT on May 15). The second total eclipse will be on November 8. This eclipse will be visible from North America, although the moon will be setting during the eclipse for observers in eastern regions. The moon will enter the penumbra at 3:01 a.m. EST on November 8 (12:01 a.m. PST) and leave it at 8:58 a.m. EST (5:58 a.m. PST). What is a lunar eclipse? A lunar eclipse is the cousin to a solar eclipse, albeit much less dramatic. Still, it makes for a great experience. As the full moon passes into the earth’s shadow, the moon can appear to darken and then change color, turning a dark red. This is because the sun’s light gets bent (refracted) through the earth’s atmosphere. The red light gets bent the most, so that’s the light that illuminates the moon’s surface during a lunar eclipse. You could think of it as the light from every sunrise and sunset on Earth lighting up the moon’s surface! For more mind-bending astronomy facts about the moon and other celestial bodies, check out Astronomy For Dummies. Stargazing a lunar eclipse Despite two total lunar eclipses happening this year, they aren’t very common. But two things make them easier for you to observe than solar eclipses: When a lunar eclipse happens, it’s often visible from anywhere on the night side of the earth. Lunar eclipses are safe to observe with your eyes, binoculars and telescopes. Want to learn how to best explore the distant wonders of the night sky? Stargazing For Dummies offers readers a detailed starter guide for the future stargazer. While you wait for the first lunar eclipse of the year, here's some interesting information about the moon's significance in world culture. The moon in classical music: From Beethoven to Chopin Did you know classical music has a few sub-genres dedicated entirely to capturing the moon’s natural beauty and emotive characteristics? For example, you’ve likely heard of Beethoven’s Moonlight Sonata or, perhaps, Debussy’s Clair de lune. These timeless pieces of music take their listeners through a moonlight-draped journey full of evocative passages, foreboding moments and somewhat mysterious tones — all inspired by that lonely white marble above. Chopin’s Nocturnes are another great example. As their name suggests, these are compositions centered entirely around the moon, nighttime, and dreaming. For more on classical music and its many timeless compositions, check out Classical Music For Dummies. The Moon in astrology: Emotions, instincts and habits Of course, no discussion about the moon would be complete without mentioning its significance in Western astrology. And yes — there’s more to it than the 12 zodiac signs. The moon's nodes, for example, refer to where its path crosses the ecliptic, which is the apparent path of the sun among the constellations over the course of a year. The north or ascending node marks the place where the moon crosses from south to north, seemingly ascending through the sky. The south, or descending node marks where the moon crosses from north to south, descending through the sky. What does this mean for astrologers? Without getting into the nitty gritty details, the moon is often associated with the “emotional self” in our astrological charts, and can represent the mysterious, hidden, and spiritual self in the tarot. To learn more about the moon’s significance in Western astrology, check out Astrology For Dummies.

Cheat Sheet / Updated 04-20-2022

The human body is a beautiful and efficient system well worth study. In order to study and talk about anatomy and physiology, you need to start from an agreed-upon view of the human body. Anatomical position for the human form is the figure standing upright, eyes looking forward, upper extremities at the sides of the body with palms turned out. You also need to be familiar with standard anatomical terms, as well as the various planes, cavities, and organ systems that make up the physical form.

Article / Updated 04-18-2022

Tornadoes are nature's most violent storms. Nothing the atmosphere dishes out is more destructive. They can sweep up anything that moves. They lift buildings from their foundations. They make a swirling cloud of violently flying debris. They are very dangerous to all living things, not only because of the sheer power of their winds, but the missiles of debris they create. Wind measuring instruments are destroyed by tornadoes, although according to reliable estimates, their winds can exceed 250 miles per hour. Flying at those speeds, pieces of straw can penetrate wood. According to most scientists, the top wind speeds in the strongest tornadoes are about 280 miles per hour. In an average year, 1,200 tornadoes are reported in the United States, far more than any other place in the world. On average, tornadoes cause 80 deaths in the U.S. every year and 1,500 injuries, although averages don't mean very much when it comes to these storms. In 1998, for example, 130 people died in tornadoes in the U.S., including 42 who were killed in an outbreak in central Florida and 34 who died in a single tornado in Birmingham, Alabama. Most human casualties are people in mobile homes and vehicles. The deadliest single tornado struck on March 18, 1925. In three and a half hours, it traveled 219 miles through Missouri, Illinois, and Indiana, killing 695 people. Most tornadoes, nearly 90 percent, travel from the southwest to the northeast, although some follow quick-changing zigzag paths. Weak tornadoes, or decaying tornadoes, often have a thin ropelike appearance. The most violent tornadoes have a broad, dark, funnel-shape that extends from a dark wall cloud of a large thunderstorm. There have been reports of some tornadoes that practically stand still, hovering over a single field. Others crawl along at 5 miles per hour. But the average tornado travels 35 miles per hour, and some have been clocked at more than 70 miles per hour. A tornado in 1917 traveled a record 293 miles. The average width of a tornado's path is about 140 yards, although some have been reported to be more than a mile wide. Most tornadoes occur between 3 p.m. and 9 p.m., although they have been known to strike at all hours of the day or night. They usually last only about 15 minutes, although, some have been known to stay on the ground for hours. Tornado Alley The size of the place known as Tornado Alley expands through spring and summer as heating from the sun grows warmer and the flow of warm moisture from the Gulf of Mexico spreads farther north. An area that includes central Texas, Oklahoma, and Kansas is the hard core of the season, but before it is over, as Figure 1 illustrates, Tornado Alley extends north to Nebraska and Iowa. Figure 1: Tornado Alley. It shrinks and swells over time, but there is only one Tornado Alley. Nowhere else in the world sees weather conditions in a combination that is so perfect for these storms. Here's what makes the storms of Tornado Alley so bad: Beginning in spring and continuing through summer, low-level winds from the south and southeast bring a plentiful supply of warm tropical moisture up from the Gulf of Mexico into the Great Plains. From down off of the eastern slopes of the Rocky Mountains or from out of the deserts of northern Mexico come other flows of very dry air that travel about 3,000 feet above the ground. From 10,000 feet, the prevailing westerly winds, sometimes accompanied by a powerful jet stream, race overhead, carrying cool air from the Pacific Ocean. Sometimes, the winds form a convective cap lid of warm air over the Plains that the rising air is eventually able to break through and explode upward into the sky. These are the ingredients for the most severe thunderstorms and most powerful twisters — sharp differences in temperatures at different levels, big contrasts in dryness and moisture, and layers of powerful winds that are blowing from different directions at different speeds. Forecasting Weather forecasters in Tornado Alley have a pretty good idea of the menu of conditions that are necessary to make severe thunderstorms, and they're pretty good at being able to forecast that severe thunderstorms are on the way. They can say that large hailstones and strong winds are likely, and a tornado is a possibility during the next several hours or the next day or two. But they can't forecast a tornado. The question of which of the conditions on the menu for severe thunderstorms actually causes tornadoes to form in these storms remains one of the most difficult mysteries of weather science. A severe thunderstorm that causes a tornado can look exactly like a severe thunderstorm that does not cause a tornado. Weather researchers have been working on the problem for years, chasing tornadoes all over the countryside, and still it is one of those things that is not well understood. The presence in the area of supercell thunderstorms really puts pressure on forecasters in local weather service field offices. The national Storm Prediction Center in Norman, Oklahoma, is on the phone giving advice, but the buck stops in the local office. The local forecasters know that a lethal tornado could come spinning down out of the dark cloud at any moment, but they can't be sure until they see it show up on a Doppler radar screen or a funnel is actually observed. Warning the public Billions of dollars have been spent in the last several years on research and computer modeling, radars and satellite technologies, and high-speed communications. Progress has been made. On average, when tornado warnings were issued in 1994, communities had six minutes to react. By 1998, the average lead time for warnings had stretched to 12 minutes. Television meteorologists and other media outlets play vital roles in such weather emergencies, continuously broadcasting the locations and predicted paths of tornadoes. Many lives are being saved by the increased public awareness and the lengthening time of advance warning that is available. In fact, the longer lead-time has reached the point where people are rethinking the idea of public shelters for tornadoes. As minutes are added to advance warnings, now it may be possible for people in harm's way to rush to a shelter before a tornado hits. More than 15,000 severe storm and tornado watches and warnings are issued by the National Weather Service every year. Most of the time, they are accurate. Sometimes, they are missed. Occasionally there are false alarms. The successes are taken for granted and often overlooked in the details of a tornado disaster. The failures and the false alarms seem to be remembered forever. Perfectly reasonable people who will forgive you for missing the rain on their picnic now have a different attitude. When it comes to tornadoes, they want perfection. Lives and limbs What are the odds of a tornado crossing your path? Even in Tornado Alley, the odds are against such an unhappy occasion. When it happens, of course, it's a disaster — but still, the odds are high against it. People think about tornadoes in tornado country the way people in the Southeast think about hurricanes and people in California think about earthquakes. It's part of the background of daily life that you really don't give very much thought to, because chances are, it's not going to happen. The five-dollar word for this is complacency — a self-satisfied unawareness of danger — and somebody is always getting on their high horse about it. The truth is, day in and day out, most people have other things to worry about that just seem more real. And it's just human nature to be optimistic, and to think things are going to turn out for the best. But it leaves you open for some terrible surprises once in a while, which is kind of sad, when you think about it. Government people in the disaster business and American Red Cross relief workers who deal with victims of these storms see this sense of surprise on people's faces all the time. A tornado watch or a warning? Don't confuse a watch with a warning. There is a big difference. Here is what they are about: Tornado watch: When National Weather Service forecasters issue a tornado watch, they are making a forecast that tornadoes are possible in your area. It's time to remain alert to signs of approaching storms and to make sure that you are prepared for an emergency. Tornado warning: This is an emergency message. A tornado has been sighted in your area, or weather radar indicates one is present. Now is the time to get to safety, to put your emergency plan into action. Tornado dos — and don'ts! The National Weather Service and the American Red Cross have put together these basic tips about tornado safety: Seek shelter immediately, preferably underground in a basement or in an interior room on the lowest floor, such as a closet or bathroom. Stay away from windows. Get out of your car or your mobile home and seek shelter in a sturdy structure. In the open, lie flat in a ditch or depression. Protect your head from flying debris. Do not try to outrun a tornado in your car. Do not seek shelter under a bridge over overpass. The idea that these are safe shelters is just plain wrong.

Cheat Sheet / Updated 04-12-2022

The ocean is big — really, really big — both as a body of water and as a topic. It encompasses physical characteristics, its ecosystems and inhabitants, its influence on climate and weather, the sustainable use of its resources, and much more. This Cheat Sheet touches on a few key topics.

Cheat Sheet / Updated 04-08-2022

Chemistry II is more than fires and smelly explosions. Chemistry II is more about solving calculations. In fact, Chemistry II has a lot more calculations and math than your Chemistry I class did. In your Chemistry II class, you need to master several formulas so you can calculate different mathematical problems, ranging from kinetics, different types of equilibrium, thermochemistry, and electrochemistry. This Cheat Sheet can serve as a quick reference to how to solve kinetics, thermodynamics, and different types of equilibrium problems.

Cheat Sheet / Updated 04-07-2022

Environmental science is a field of study focused on Earth’s environment and the resources it provides to every living organism, including humans. Environmental scientists focus on studying the environment and everything in it and finding sustainable solutions to environmental issues. In particular, this means meeting the needs of human beings (and other organisms) today without damaging the environment, depleting resources, or compromising the earth’s ability to meet the resource needs of the future. A sustainable solution to an environmental problem must be ecologically sound, economically viable, and culturally acceptable. This Cheat Sheet summarizes some key aspects of what environmental scientists study.

Cheat Sheet / Updated 04-07-2022

Botany is the study of plants. Plants are very similar to people in a lot of ways, but they also have some differences that can be hard to wrap your brain around. And, like any science class, botany can get a little overwhelming at times. So, here are a few items to help you grasp some of the big ideas in botany.

Cheat Sheet / Updated 03-28-2022

Solving physics problems correctly is a lot easier when you have a couple tricks under your belt. In fact, you can greatly improve your odds of getting the right answer if you make sure that what you calculated is plausible in the real world. Another trick is to draw your own visual when one isn’t provided for you — no artistic ability required. It also helps to have this handy reference for some of the most common unit prefixes and unit conversions you’re bound to encounter in your physics homework.