Science Articles

Article / Updated 09-14-2023

Here are some favorite facts about astronomy and, in particular, Earth and its solar system. With the following information under your belt, you may be ready to handle the astronomy questions on television quiz shows and inquiries from friends and family. You have tiny meteorites in your hair Micrometeorites, tiny particles from space visible only through microscopes, are constantly raining down on Earth. Some fall on you whenever you go outdoors. But without the most advanced laboratory equipment and analysis techniques, you can't detect them. They get lost in the great mass of pollen, smog particles, household dust, and dandruff that resides on the top of your head. A comet's tail often leads the way A comet tail isn't like a horse tail, which always trails behind as the horse gallops ahead. A comet tail always points away from the Sun. When a comet approaches the Sun, its tail, or tails, stream behind it; when the comet heads back out into the solar system, the tail leads the way. Earth is made of rare and unusual matter The great majority of all the matter in the universe is so-called dark matter, invisible stuff that astronomers haven't yet identified. And most ordinary or visible matter is in the form of plasma (hot, electrified gas that makes up normal stars such as the Sun) or degenerate matter (in which atoms or even the nuclei within the atoms are crushed together to unimaginable density, as found in white dwarfs and neutron stars). You don't find dark matter, degenerate matter, or much plasma on Earth. Compared to the great bulk of the universe, Earth and earthlings are the aliens. High tide comes on both sides of Earth at the same time Ocean tides on the side of Earth that faces the Moon aren't appreciably higher than tides on the opposite side of Earth at the same time. This may defy common sense, but not physics and mathematical analysis. (The same goes for the smaller ocean tides raised by the Sun.) On Venus, the rain never falls on the plain In fact, the constant rain on Venus never falls on anything. It evaporates before it hits the ground, and the rain is pure acid. (The common name for evaporating rain is virga.) Rocks from Mars dot Earth People have found about 100 meteorites on Earth that come from the crust of Mars, blasted from that planet by the impacts of much larger objects — perhaps from the asteroid belt. Statistically, many more undiscovered Mars rocks must have fallen into the ocean or landed in out-of-the-way places where they haven't been spotted. Pluto was discovered from predictions of a false theory Percival Lowell predicted the existence and approximate location of the object that we now call Pluto. When Clyde Tombaugh surveyed the designated region, he discovered Pluto. But now scientists know that Lowell's theory, which inferred the existence of Pluto from its gravitational effects on the motion of Uranus, was wrong. In fact, Pluto's mass is much too small to produce the "observed" effects. Furthermore, the "gravitational effects" were just errors in measuring the motion of Uranus. (Not enough information was available about Neptune's motion to study it for clues.) The discovery of Pluto took hard work, but as it happened, it was just plain luck. And although Lowell predicted the existence of a planet, as Pluto was first termed, the International Astronomical Union has since downgraded it to dwarf planet. Sunspots aren't dark Almost everyone "knows" that sunspots are "dark" spots on the Sun. But in reality, sunspots are simply places where the hot solar gas is slightly cooler than its surroundings. The spots look dark compared to their hotter surroundings, but if all you can see is the sunspot, it looks bright. A star in plain view may have exploded, but no one knows Eta Carinae is one of the most massive, fiercely shining stars in our galaxy, and astronomers expect it to produce a powerful supernova explosion at any time, if it hasn't already. But because light takes about 8,000 years to travel from Eta Carinae to Earth, an explosion that occurred many years ago isn't visible to us yet. You might have seen the Big Bang on an old TV set The Big Bang Theory premiered in 2007, but the real Big Bang may have made its TV debut even before that. Some of the snow — a pattern of interference that looks like little white spots or streaks on old black-and-white television sets — was actually radio waves the TV antenna received from the cosmic microwave background, a glow from the early universe in the aftermath of the Big Bang. When this radiation was actually discovered at the Bell Telephone Laboratories, scientists studied many possible causes of the unexpected "noise" in the radio receiver. They even investigated pigeon droppings, or "white dielectric material" in science speak, as a possible cause but later dropped that suggestion.

Article / Updated 09-14-2023

The multiverse is a theory that suggests our universe is not the only one, and that many universes exist parallel to each other. These distinct universes within the multiverse theory are called parallel universes. A variety of different theories lend themselves to a multiverse viewpoint. Not all physicists really believe that these universes exist. Even fewer believe that it would ever be possible to contact these parallel universes. Following, are descriptions of different levels, or types of parallel universes, scientists have discussed. Level 1: If you go far enough, you’ll get back home The idea of Level 1 parallel universes basically says that space is so big that the rules of probability imply that surely, somewhere else out there, are other planets exactly like Earth. In fact, an infinite universe would have infinitely many planets, and on some of them, the events that play out would be virtually identical to those on our own Earth. We don’t see these other universes because our cosmic vision is limited by the speed of light — the ultimate speed limit. Light started traveling at the moment of the big bang, about 14 billion years ago, and so we can’t see any further than about 14 billion light-years (a bit farther, since space is expanding). This volume of space is called the Hubble volume and represents our observable universe. The existence of Level 1 parallel universes depends on two assumptions: The universe is infinite (or virtually so). Within an infinite universe, every single possible configuration of particles in a Hubble volume takes place multiple times. If Level 1 parallel universes do exist, reaching one is virtually (but not entirely) impossible. For one thing, we wouldn’t know where to look for one because, by definition, a Level 1 parallel universe is so far away that no message can ever get from us to them, or them to us. (Remember, we can only get messages from within our own Hubble volume.) Level 2: If you go far enough, you’ll fall into wonderland In a Level 2 parallel universe, regions of space are continuing to undergo an inflation phase. Because of the continuing inflationary phase in these universes, space between us and the other universes is literally expanding faster than the speed of light — and they are, therefore, completely unreachable. Two possible theories present reasons to believe that Level 2 parallel universes may exist: eternal inflation and ekpyrotic theory. In eternal inflation, recall that the quantum fluctuations in the early universe’s vacuum energy caused bubble universes to be created all over the place, expanding through their inflation stages at different rates. The initial condition of these universes is assumed to be at a maximum energy level, although at least one variant, chaotic inflation, predicts that the initial condition can be chaotically chosen as any energy level, which may have no maximum, and the results will be the same. The findings of eternal inflation mean that when inflation starts, it produces not just one universe, but an infinite number of universes. Right now, the only noninflationary model that carries any kind of weight is the ekpyrotic model, which is so new that it’s still highly speculative. In the ekpyrotic theory picture, if the universe is the region that results when two branes collide, then the branes could actually collide in multiple locations. Consider flapping a sheet up and down rapidly onto the surface of a bed. The sheet doesn’t touch the bed only in one location, but rather touches it in multiple locations. If the sheet were a brane, then each point of collision would create its own universe with its own initial conditions. There’s no reason to expect that branes collide in only one place, so the ekpyrotic theory makes it very probable that there are other universes in other locations, expanding even as you consider this possibility. Level 3: If you stay where you are, you’ll run into yourself A Level 3 parallel universe is a consequence of the many worlds interpretation (MWI) from quantum physics in which every single quantum possibility inherent in the quantum wavefunction becomes a real possibility in some reality. When the average person (especially a science fiction fan) thinks of a “parallel universe,” he’s probably thinking of Level 3 parallel universes. Level 3 parallel universes are different from the others posed because they take place in the same space and time as our own universe, but you still have no way to access them. You have never had and will never have contact with any Level 1 or Level 2 universe (we assume), but you’re continually in contact with Level 3 universes — every moment of your life, every decision you make, is causing a split of your “now” self into an infinite number of future selves, all of which are unaware of each other. Though we talk of the universe “splitting,” this isn’t precisely true. From a mathematical standpoint, there’s only one wavefunction, and it evolves over time. The superpositions of different universes all coexist simultaneously in the same infinite-dimensional Hilbert space. These separate, coexisting universes interfere with each other, yielding the bizarre quantum behaviors. Of the four types of universes, Level 3 parallel universes have the least to do with string theory directly. Level 4: Somewhere over the rainbow, there’s a magical land A Level 4 parallel universe is the strangest place (and most controversial prediction) of all, because it would follow fundamentally different mathematical laws of nature than our universe. In short, any universe that physicists can get to work out on paper would exist, based on the mathematical democracy principle: Any universe that is mathematically possible has equal possibility of actually existing.

Article / Updated 09-05-2023

You’ve probably noticed that September just “feels” like a time of transition. For those of us in the Northern Hemisphere, it’s the time of the year when temperatures cool off, birds begin gathering for migration, and the trees start showing color. All of this occurs around the autumnal equinox, between September 21 and September 24 (in 2023, the equinox is the 23rd) marking the start of fall for people in the Northern Hemisphere. Earth’s tilt and orbit make it all happen Our planet is tilted about 23.5 degrees on its axis as it travels around the sun, and it stays tilted in the same direction as it orbits. This means the sun’s light hits the Earth at different angles. So, different parts of the Earth receive varying amounts of the sun’s light and warmth throughout the year — in other words, we have seasons. However, twice during Earth’s orbit, on the autumnal (September) equinox and the vernal, or spring (March), equinox, the sun is directly over the planet’s equator, and everybody across the globe experiences a nearly equal amount of daylight and darkness. A few interesting facts about the equinoxes and Earth’s orbit: The word equinox comes from two Latin words: aequus (equal) and nox (night). During the autumnal and vernal equinoxes, people across the globe can see the sun rise above the horizon due east and set due west. So, it’s a good time to find due east and west. Because of the Earth’s tilt on its axis, its northern and southern hemispheres trade places throughout the year receiving the sun’s light and warmth most directly. For people in the Southern Hemisphere, the equinoxes signal the opposite seasonal transitions: September marks the beginning of spring, and the March equinox marks the beginning of autumn. If you live in the Northern Hemisphere, starting on the autumnal equinox, you can observe a slight daily change in the sun’s arc across the sky — it’s shifting to the south. A number of prehistoric sites, like Stonehenge and Newgrange in the United Kingdom, were possibly used by ancient cultures to predict equinoxes and the summer and winter solstices — the longest and shortest days of sunlight during the year). To learn more about the Earth's orbit, our solar system, the stars, and beyond, check out the fifth edition of Astronomy For Dummies. Celebrations around the fall equinox Over the centuries, before humans could scientifically explain the autumnal equinox, they observed the sun’s changing position in the sky and nature's transitions in the fall and spring, and they marked these times with rituals and celebrations. Some of these ancient observations were incorporated into Greek mythology and other cultures' mythology, and into religious practices. Today, there are still many cultural and religious traditions practiced around the equinoxes. Here are summaries of just a few: Mabon — United Kingdom: Mabon is a fall equinox tradition created by the ancient Celtic people and celebrated by pagans today. It is one of the oldest harvest festivals in Europe. Acknowledging the autumnal equinox, the holiday is meant to give thanks for the warm, summer months, the fall harvest, and to get ready for the beginning of winter. The Snake of Sunlight — Mexico: The ancient Mayan and Aztec civilizations in Mexico celebrated the equinoxes at the site of Chichen-Itza, a city that existed about 1,500 years ago in what is now the state of Yucatan. When you visit the Chichen-Itza ruins today, you see a massive pyramid, a monument the Mayans built to honor the god Kulkulcan (Quetzalcoatl to the Aztecs). The deity was a feathered serpent, and the ancient Mayans believed it visited the temple twice a year — on the autumn and spring equinoxes. Chichen-Itza is a popular tourist attraction, and many come to witness a special effect that happens on the equinoxes. The pyramid’s steps are oriented so that in the afternoon of the two equinox days, the shadow on the pyramid looks like a snake slowly slithering down the stairs, with its tail at the top and its head at the bottom. Higan — Japan: Higan is a Buddhist tradition taking place around the equinoxes – three days before the equinox day and three days after. Higan means crossing over to the “other shore,” symbolizing the world of enlightenment, or spiritual awakening. For Buddhists, Higan is a time to reflect on one’s life and renew religious practices. During Higan in Japan, people visit their ancestors’ graves, where they tidy up the gravesites and place flowers and incense.

Article / Updated 08-31-2023

Hurricanes are scary, and few people think clearly under that stress. Additionally, a lot of what you need to do to best weather a storm starts well ahead of hurricane season — which runs from late May through November. Start your hurricane safety plan ahead of a storm, while things are calm. The following steps put you and your family in the best position to protect your home and yourselves when a hurricane is on its way. Have an evacuation plan ready . Determine whether you’re in an evacuation zone and watch for updates; the course of a storm may change. Scout your yard and remove any furniture or other items that may get picked up by the wind and fly through windows or otherwise cause destruction. Put any important documents in a watertight container, along with medications and insurance cards. Charge your phone and any other devices you plan to use or carry with you. Turn your fridge to the coldest setting and put a thermometer in there. You’re likely to lose electricity, and a colder starting temp will keep your food cold longer. The thermometer will let you know whether your milk is a lost cause when the electricity’s back. Look into hurricane insurance If you live in an area commonly hit by hurricanes, standard homeowner’s insurance isn’t going to provide everything you need. Such a policy addresses structural damage and typically includes a higher deductible whenever that damage arises from a hurricane. And it may be inadequate to cover your costs for rebuilding and the living expenses you pay while you rebuild. Be sure to look closely at coverage for additional living expenses (ALE), which are essential after extensive storm damage that requires you to rent living space while damage is repaired. Find out what your policy covers and what it excludes. For example, a standard homeowner’s policy probably doesn't cover damage from sewer backups, which are common after major storms. You actually can buy a specific policy for this instance. Much of the damage from a hurricane comes from flooding, which also requires a separate policy. To get the full value from the policies you do buy, make sure you have a complete inventory of what you own and how much it’s worth. Doing so will make filing claims later on much smoother. Keep this documentation and your policies in a water-safe container that you can easily move with you when you evacuate. If you rent or own an apartment in a co-op, you need your own insurance policies, but you also want to be aware of the coverage your building has in place. Hurricane “watch” or “warning?” What makes a watch different from a warning? These terms actually have very specific meanings. A hurricane watch tells you that hurricane-force winds may appear within 48 hours. If you hear a hurricane warning, know that you’re likely to encounter hurricane-force winds within 36 hours. Warnings usually are issued for about 300 miles of coastline at a time. Although satellite technology makes predicting a storm’s approach easy, determining exactly where it will make landfall is still difficult. If you are told to evacuate ahead of a hurricane, never hesitate. Leave as soon as possible. But, if whatever reason, you are unable to get out and find yourself caught in the storm, here's how to survive. Address kids, pets, and special needs during a storm Maybe one family member needs to keep insulin at a just-right temperature, or you have a dog who requires eye drops every four hours. Situations like these require more detailed planning. Be sure to think through a week’s worth of needs for each family member. That may mean finding a physician and forwarding medical records to a medical center in the city where you’ll wait out the storm at your cousin’s house, or it may require even more careful planning. Just make sure that as soon as you know a storm is possible, you carefully consider each family member’s needs for several days. Include the pets, the kids, and the grandma you’ll pick up on the way out of town. For pets and kids, concerns aren’t all that different: Be ready to feed and distract, at a minimum. You need to prepare whatever food, drinks, and toys or special objects will keep the kids and pets as content as possible during the storm. Make sure that your pets have been microchipped or that they’re wearing ID tags. It’s all too easy to become separated during the chaos of a storm. If your kids attend school or daycare, make sure that you know the schools’ evacuation plans. Laminate an “in case of emergency” card for each child that includes your contact information and that of a friend or relative who lives elsewhere and may be able to provide a safe place to stay if a storm arises. As much as possible, keep up your routines, which will reassure members of your family who rely on you. Your kids especially look to you for cues about how to act, so do your best to keep calm. Prepare a storm evacuation plan Uprooting your life in response to an incoming storm presents a host of challenges, like where you’ll end up and who’s in charge of the pet-food supply. Make the transition as smooth as possible by having an evacuation plan in place. It should cover the following: Where you’ll meet if you become separated: Pick a place close to home and one farther away where you can meet up, and choose a family member to serve as point person. This person is who everyone checks in with if you can’t stay in one place. Where you’ll stay: Identify a couple of options ahead of time. Shelters will arise nearby (use FEMA.gov to find them), or maybe a hospitable friend or family member lives outside the evacuation zone. If you have pets, this part of the planning is trickier; most shelters accept only service dogs. How you’ll get there: If you have a car, make sure it’s in good working order and your gas tank is full. If not, plan farther ahead for public transportation (which will shut down as the storm nears) or for someone to drive you. Supplies: Get your disaster supplies kit ready well ahead of time. Grab a phone charger for the car, and if you’re traveling far, have snacks and distractions ready — especially if you’re traveling with kids. Maps: Downed trees or flooding may require you to change your route at the last moment, so be ready with low-tech navigation that cannot let you down no matter the circumstances. IDs and cash: Appoint a family member to make sure everyone has an ID and a little bit of cash. Don’t let this be the time you’re caught with your wallet in your gym bag. Updates: If you don’t want to keep tuned to the weather on the car radio, ask one person to track the storm until you’re safely out of range. Emergency instructions sometimes change as the storm progresses, and you need to have the latest information as you evacuate. Notice: Identify a close friend or family member to check in with when you leave and when you have arrived at shelter outside the evacuation zone. Resolve: Staying in your home is tempting, even when you’ve been ordered to evacuate. Resolve, as a household, to follow those orders and accept no alternatives. Hurricanes are deadly. Agreeing ahead of time that you’ll evacuate can save valuable time debating the issue later. If you’re on the coast, get out well in advance of the storm surge When a hurricane pushes ocean water ashore, that push is called a storm surge and is responsible for more deaths and damage than any other part of the storm. Depending on how and where the storm hits, a storm surge — measured in how far above sea level the water rises — can bring almost 30 feet of water to land. This water moves at high speed, bringing tremendous destructive power to everything in its path. These surges are unpredictable, and they often arrive before the storms themselves. When they hit, water levels can rise ten feet in just minutes. Help cannot make it to you under these circumstances, and you are unlikely to be able to drive away from a storm surge. If you’re near a coast and anywhere close to a hurricane’s path, you must evacuate. If you see it coming, it’s too late. The surge can easily go from an inch to several feet before you even make it out of your driveway. Keep an axe in your attic so that if for some reason you are trapped in your home during a surge, you have an escape route through the roof. Travel to hurricane prone areas Because hurricanes happen near coastlines, a lot of popular vacation spots are susceptible. When you’re thinking about planning a vacation, take a look at the storm season before you book tickets and hotel rooms. Travel insurance that covers natural disasters can help, and you should check with hotels and airlines about policies regarding refunds or rescheduling in the event of a storm. For official communications related to hurricanes, please visit the websites of FEMA, Department of Homeland Security, and the National Hurricane Center for the latest information. Please note that this is general preparedness information, not specific to a particular storm.

Article / Updated 08-17-2023

If, for whatever reason, you were unable to get out of the area before a hurricane strikes, making the right moves may be a life-or-death matter. More hurricanes happen during September than any other month, but hurricane season spans late May through November and can push relentless rain and wind up to 100 miles inland. Preparation is important. If you’re told to evacuate, do not hesitate. And if you’re caught in a storm, here are tips on how to stay safe during a hurricane: Stay inside. Don’t try to move to another location. You may not be in the ideal spot, but being on the roads when a storm is underway or imminent is too dangerous to risk. Floodwaters come up fast and move quickly. Water doesn’t need to be more than a foot deep to sweep your car away. Make sure all doors and windows are shut tight. Close your curtains or blinds to put a buffer between you and the glass, which may break from winds, branches, or flying debris. If you have time, bracing exterior doors with heavy furniture is a good idea. Don’t tape or crack your windows. If you haven’t braced your windows with plywood or permanent storm shutters, you’re out of luck at this point. The advice to tape windows is useless, and getting near them as winds pick up is incredibly dangerous. You may also have heard that you should crack your windows to relieve the pressure, and this, too, is bad advice. Letting in the wind and the rain does not help the situation at all. Keep your windows shut, and keep away from them. Stay in the lowest level of the building, and find an interior room. That may be a closet, bathroom, or stairwell. (Stay out of elevators during a storm.) Upper-level and exterior rooms are more vulnerable to damage from high winds; you’re safest where there are the most barriers between you and the storm. Bring pets inside. Avoid using candles. High winds and flame make the risk of fire much too great. Reach for a flashlight instead. Shield yourself with whatever you can. Especially if you don’t have an interior room, putting a table between yourself and a window or door may keep you safe from glass or debris. Cover yourself with a sofa cushion or mattress. You may be instructed to turn off your utilities at some point in anticipation of losing power, so it’s important to monitor for this direction. If you’re without power for either reason, avoid opening your refrigerator so that it keeps food cold as long as possible. Your home may flood during a hurricane. If it does, turn off your electricity and move to a higher floor. Floodwater may be contaminated with sewage. At some point, the wind and rain are likely to die down. Don’t be tempted to go outside; this may just be the eye of the storm and a lead-in to more high winds and pounding rain. For official communications related to hurricanes, please visit the websites of FEMA, Department of Homeland Security, and the National Hurricane Center for the latest information. Please note that this is general preparedness information, not specific to a particular storm.

Article / Updated 08-14-2023

A hurricane starts as a tropical storm, and a tropical storm reaches hurricane status when it develops and sustains winds moving at least 74 miles per hour. The storm itself is a cyclone with winds spiraling (at least in the Northern Hemisphere) in a counterclockwise direction. These cyclones, or rotating storms, develop over any ocean but are called hurricanes when they arise over the Atlantic or Northern Pacific. In other areas, they’re called typhoons or tropical cyclones. How does a hurricane form, and when is hurricane season? How a hurricane comes together isn’t precisely known, but it requires warm water (at least 79 degrees Fahrenheit) and winds that rise without much change in direction. Those factors combine to create winds that move in a spiral. As a storm grows, it may cover a diameter of more than 600 miles and gust at more than 200 miles per hour — nearly the top speed of a Formula One racecar. The faster the wind, the higher the storm rating and the greater the threat to everyone and everything in its path. Hurricanes are rated by intensity on a scale of 1 to 5, with a Category 1 storm showing the lowest intensity and winds of no more than 95 mph. Those in Category 5 top 156 mph. Hurricanes Maria (Dominica and Puerto Rico) and Irma (Florida) were Category 5 storms that made landfall in 2017. Windows and doors may get smashed from winds at the Category 2 level and above. Hurricane season runs from late May through November. What is the center of a hurricane, and other storm anatomy questions A hurricane is made up of several parts. If you could look closely at a cross-section of a hurricane, here’s what you’d see, starting from the center of the hurricane: Eye: An oasis of calm surrounded by hurtling winds and rain, the eye of a hurricane is about 20 to 40 miles of low winds, light rain, and even clear skies where the air is sinking rather than rising. Eye wall: Swirling around the eye, the eye wall is a band of thunderstorms where the rain and wind are strongest. Air is moving rapidly here in the direction of the eye of the storm, rising before it sinks again at the storm’s center. Feeder bands: Stretching sometimes hundreds of miles from the center of the storm, feeder bands of a hurricane are bands of heavy rain and wind sometimes include tornadoes. Outflow: Hurricanes stretch up much farther than out. Way up at a plane’s cruising altitude, the outflow of a hurricane is a huge swath of clouds swirling in the opposite direction of a hurricane. Hurricane prone areas If you live in Montana, you’re in the clear. Because hurricanes develop over warm ocean waters and lose strength as they travel over land, they do their worst near the country’s coasts. Here are the counties and areas that are prone and have been most often hit from 1960 to 2008, according to the U.S. Department of Commerce: Monroe County, Florida Lafourche Parish, Louisiana Carteret County, North Carolina Dare County, North Carolina Hyde County, North Carolina Jefferson Parish, Louisiana Palm Beach County, Florida Miami-Dade County, Florida Bernard Parish, Louisiana Cameron Parish, Louisiana What is hurricane storm surge? Hurricanes form over warm oceans, and when they reach land they push huge amounts of ocean water onto the shore with them. This is usually described as a “wall of water” but more specifically is an extremely fast rise in water above sea level. It technically is known as the storm surge. During Hurricane Katrina in 2005, the storm surge topped 25 feet and was a major factor in that storm’s high death toll. (At least 1,500 people died during Katrina.) A storm surge unleashes the incredible power of wind and water, sweeping up trees, cars, and buildings as it moves. Even standing in just six inches of these powerful waters would be difficult. A storm surge may reach land ahead of the storm, and when it does it may flood the roads you’d have used to evacuate. If you live near the shore, get out well in advance of the storm’s landfall. The storm surge may hit a day earlier, and it’s the deadliest element of a hurricane. The elements of a storm surge, like strength and angle of the storm, the shape of the land where it hits, and the shape of the continental shelf at the coastline, combine in unpredictable ways. In other words, no one can predict the intensity of a storm surge. Erring on the side of caution is warranted, especially when you consider that a cubic yard of water weighs almost a ton. The risk of damage from a storm surge is highest in the following states: Florida Louisiana Texas New Jersey New York You don’t have to live on a coast to get hit by the rains and winds a hurricane creates, and if you are in a high-risk area, you need to take steps — before hurricane season hits — to prepare yourself, your family, and your home for the potentially deadly damage. A hurricane is nature at its most destructive. These tropical cyclones don’t sneak up: When a hurricane is on its way, you’ll have several days’ warning before it lands, so keep an eye on the news or sign up for hurricane alerts. But sometimes several days isn’t enough. If you act much earlier, you won’t be fighting your neighbors for the last jugs of water on the store shelves. Create a hurricane preparedness checklist You want to prepare for a hurricane before hurricane season even starts, and a hurricane preparedness checklist can help you make sure you’ve got everything in order. Avoid the mad dash for supplies by prepping a hurricane disaster supply kit before you’re likely to need it. You want a large plastic tub or duffle bag so that everything in your kit is in one place and is ready to move. Pack it with the following: Water jugs: Traditional wisdom says bring a gallon per person per day for a minimum of three days. If you have room to carry it, err on the side of too much water. Food: Pack up enough nonperishable food for a few days — and a can opener. Think canned tuna and fruit, dry cereal, peanut butter, or granola bars, and focus on high-energy foods rather than salty snacks that will lead you to use too much of your water. Pack foods you like and some comfort foods because you’re going into a high-stress situation. No need to add to your angst. First-aid kit Flashlight and extra batteries Portable radio (you may not have Internet service) and extra batteries Cellphone charger Toilet paper Blankets or sleeping bags Glasses or contacts and contact solution A change of clothes for each family member Distractions like games, toys, and books Pet food Insect repellent Whistle (to signal for help) or flares Waterproof containers or plastic bags Other ways to prepare for a hurricane Preparation isn’t just what you do when a storm is imminent. Many of the moves that best protect you are the ones you make far ahead of time, like building a hurricane kit. You also want to take these steps: Have a plan. And make sure everyone in your household knows it. Choose a point person for everyone to contact and a meeting place if you get separated. Stay current on weather conditions. Keep a close eye on weather updates and emergency guidelines for your area. Minimize tree-related damage. Remove any dead wood from your trees; keep them trimmed so that they’re healthy and branches don’t reach your home. Maintain your car. Keep your car in good working order; gas up your tank when a storm nears. Protect your windows. Plan how you’ll protect your windows with permanent storm shutters or plywood. Long before a storm hits, make sure you have the right number and sizes of 5/8-inch-thick plywood sheets ready to be nailed in. Reinforce your exterior doors. They’re more likely to stay put against a hurricane if they’re secured by three hinges per door and a one-inch deadbolt. Prepare for rain run-off. Regularly clean gutters and drains so that they’re in the best shape to handle heavy rain. Get and maintain the right insurance. Purchase adequate homeowner’s insurance and become well-acquainted with its terms. Arm yourself with information Several organizations specialize in weather and emergency information. Check out these resources for further details about staying safe in a hurricane: The American Red Cross offers several guides for hurricane preparedness and safety and can tell you how to donate to relief efforts. FEMA keeps you alerted to storm progress, evacuation orders, and shelter locations during a hurricane. The Department of Homeland Security’s gov gives you hour-by-hour checklists of preparation and safety guidelines for hurricanes. You can track a storm through the National Hurricane Center Weather Underground tracks tropical storm and hurricane activity in tremendous detail and offers historical data as well as general preparedness information. For official communications related to hurricanes, please visit the websites of FEMA, Department of Homeland Security, and the National Hurricane Center for the latest information. Please note that this is general preparedness information, not specific to a particular storm.

Article / Updated 07-31-2023

In physics, it’s important to know the difference between conservative and nonconservative forces. The work a conservative force does on an object is path-independent; the actual path taken by the object makes no difference. Fifty meters up in the air has the same gravitational potential energy whether you get there by taking the steps or by hopping on a Ferris wheel. That’s different from the force of friction, which dissipates kinetic energy as heat. When friction is involved, the path you take matters — a longer path will dissipate more kinetic energy than a short one. For that reason, friction is a nonconservative force. For example, suppose you and some buddies arrive at Mt. Newton, a majestic peak that rises h meters into the air. You can take two ways up — the quick way or the scenic route. Your friends drive up the quick route, and you drive up the scenic way, taking time out to have a picnic and to solve a few physics problems. They greet you at the top by saying, “Guess what — our potential energy compared to before is mgh greater.” “Mine, too,” you say, looking out over the view. You pull out this equation: ΔPE = mg(hf - hi) This equation basically states that the actual path you take when going vertically from hi to hf doesn’t matter. All that matters is your beginning height compared to your ending height. Because the path taken by the object against gravity doesn’t matter, gravity is a conservative force. Here’s another way of looking at conservative and nonconservative forces. Say you’re vacationing in the Alps and your hotel is at the top of Mt. Newton. You spend the whole day driving around — down to a lake one minute, to the top of a higher peak the next. At the end of the day, you end up back at the same location: your hotel on top of Mt. Newton. What’s the change in your gravitational potential energy? In other words, how much net work did gravity perform on you during the day? Gravity is a conservative force, so the change in your gravitational potential energy is 0. Because you’ve experienced no net change in your gravitational potential energy, gravity did no net work on you during the day. The road exerted a normal force on your car as you drove around, but that force was always perpendicular to the road (meaning no force parallel to your motion), so it didn’t do any work, either. Conservative forces are easier to work with in physics because they don’t “leak” energy as you move around a path — if you end up in the same place, you have the same amount of energy. If you have to deal with nonconservative forces such as friction, including air friction, the situation is different. If you’re dragging something over a field carpeted with sandpaper, for example, the force of friction does different amounts of work on you depending on your path. A path that’s twice as long will involve twice as much work to overcome friction. What’s really not being conserved around a track with friction is the total potential and kinetic energy, which taken together is mechanical energy. When friction is involved, the loss in mechanical energy goes into heat energy. You can say that the total amount of energy doesn’t change if you include that heat energy. However, the heat energy dissipates into the environment quickly, so it isn’t recoverable or convertible. For that and other reasons, physicists often work in terms of mechanical energy.

Article / Updated 07-27-2023

Normally, only a few meteors per hour are visible — more after midnight than before and (for observers in the Northern Hemisphere) more in the fall than in the spring. But on certain occasions every year, you may see 10, 20, or even 50 or more meteors per hour in a dark, moonless sky far from city lights. Such an event is a meteor shower, when Earth passes through a great ring of billions of meteoroids that runs all the way around the orbit of the comet that shed them. The following figure illustrates the occurrence of a meteor shower. The direction in space or place on the sky where a meteor shower seems to come from is called the radiant. The most popular meteor shower is the Perseids, which, at its peak, produces as many as 80 meteors per hour. (The Perseids get their name because they seem to streak across the sky from the direction of the constellation Perseus, the Hero, their radiant. Meteor showers are usually named for constellations or bright stars [such as Eta Aquarii] near their radiants.) A few other meteor showers produce as many meteors as the Perseids, but fewer people take the time to observe them. The Perseids come in August, when the balmy nights in North America and Europe often are perfect for skywatching, but the other leading meteor showers — the Geminids and Quadrantids — streak across the sky in December and January, respectively, when the weather is worse in the Northern Hemisphere and observers' ambitions are limited. The table lists the top annual meteor showers. The dates in the table are the nights when the showers usually reach their peak. Some showers go on for days, and others for weeks, raining down meteors at lower rates than the peak values. The Quadrantids may last for just one night or only a few hours. Top Annual Meteor Showers Shower Name Approximate Date Meteor Rate (Per Hour) Quadrantids Jan. 3–4 90 Lyrids Apr. 21 15 Eta Aquarids May 4–5 30 Delta Aquarids July 28–29 25 Perseids Aug. 12 80 Orionids Oct. 21 20 Geminids Dec. 13 100 The Quadrantids' radiant is in the northeast corner of the constellation Bootes, the Herdsman. The meteors are named for a constellation found on 19th-century star charts that astronomers no longer officially recognize. In addition to losing their namesake, the Quadrantids seem to have lost the comet that spawned them — their origin was a mystery until 2003, when astronomer Petrus Jenniskens found that an object named 2003 EH1 may be their parent comet. The Geminids are a meteor shower that seems to be associated with the orbit of an asteroid rather than a comet. However, the "asteroid" is probably a dead comet, which no longer puffs out gas and dust to form a head and tail. The object 2003 EH1, the likely parent of the Quadrantids, may be a dead comet, too. The Leonids are an unusual meteor shower that occurs around November 17 every year, usually to no great effect. But every 33 years, many more meteors are present than usual, perhaps for several successive Novembers. Huge numbers of Leonids were seen in November 1966 and again in November 1999, 2000, 2001, and 2002, at least for brief times at some locations. The next great display likely will come in 2032. Don't forget to look for it. You almost never see as many meteors per hour as lsited. The official meteor rates are defined for exceptional viewing conditions, which few people experience nowadays. But meteor showers vary from year to year, just like rainfall. Sometimes people do see as many Perseids as listed. On rare occasions, they see many more than expected. Such inconsistency is why keeping accurate records of the meteors that you count can be helpful to the scientific record. For more information on upcoming meteor showers, check out the American Meteor Society website. Do you live south of the equator? If so, check out the list of meteor showers visible from the Southern Hemisphere on the website of the Royal Astronomical Society of New Zealand. To track meteors, you need an accurate time source, a way to record your observations, and a dim flashlight to see what you're doing. For the latter, it's best to use a red flashlight, which you can purchase, or make from an ordinary flashlight by wrapping red transparent plastic around the bulb. Some astronomers paint the lamp with a thin coat of red nail polish. If you use a white light, you dazzle your eyes and make it impossible to see the fainter stars and meteors for 10 to 30 minutes, depending on the circumstances. Letting your vision adjust to the dark is called getting dark adapted and is a step you want to take every time you observe the night sky. The best way to watch and count meteors is to recline on a lounge chair. (You can do pretty well just lying on a blanket with a pillow, but you're more likely to fall asleep in that position and miss the best part of the show.) Tilt your head so you're looking slightly more than halfway up from the horizon to the zenith — the optimum direction for counting meteors. Take notes. And be sure you have a thermos of hot coffee, tea, or cocoa! You don't have to face the radiant when you observe a meteor shower, although many people do. The meteors streak all over the sky, and their visible paths may begin and end far from the radiant. But you can visually extrapolate the meteors' paths back in the direction from which they seem to come, and the paths point back to the radiant. Identifying a radiant in that way is how you can tell a shower meteor from a sporadic one. If you do face the radiant, however, you see some meteors that seem to have very short paths, even though they appear fairly bright. The paths appear short because the meteors are coming almost right at you. Fortunately, the shower meteoroids are microscopic and won't make it to the ground. For more information on meteor showers, including historical events, facts, and advice on observing, head to the Sky and Telescope site and enter "Shooting Stars" in the search window. Then you can download the free Shooting Stars e-book (you may have to register your email address).

Article / Updated 07-10-2023

Chiral molecules usually contain at least one carbon atom with four nonidentical substituents. Such a carbon atom is called a chiral center (or sometimes a stereogenic center), using organic-speak. Any molecule that contains a chiral center will be chiral, with the exception of a meso compound (see below for how to identify these). For example, the compound shown here contains a carbon atom with four nonidentical substituents; this carbon atom is a chiral center, and the molecule itself is chiral, because it's nonsuperimposable on its mirror image. A chiral center You need to be able to quickly spot chiral centers in molecules. All straight-chain alkyl group carbons (CH3 or CH2 units) will not be chiral centers because these groups have two or more identical groups (the hydrogens) attached to the carbons. Neither will carbons on double or triple bonds be chiral centers because they can't have bonds to four different groups. When looking at a molecule, look for carbons that are substituted with four different groups. See, for example, if you can spot the two chiral centers in the molecule shown here. A molecule with two chiral centers Because CH3 and CH2 groups cannot be chiral centers, this molecule has only three carbons that could be chiral centers. The two leftmost possibilities, identified in the next figure, have four nonidentical groups and are chiral centers, but the one on the far right has two identical methyl (CH3) groups and so is not a chiral center. The chiral centers in a long molecule How to identify molecules as meso compounds A meso compound contains a plane of symmetry and so is achiral, regardless of whether the molecule has a chiral center. A plane of symmetry is a plane that cuts a molecule in half, yielding two halves that are mirror reflections of each other. By definition, a molecule that's not superimposable on its mirror image is a chiral molecule. Compounds that contain chiral centers are generally chiral, whereas molecules that have planes of symmetry are achiral and have structures that are identical to their mirror images. The plane of symmetry in meso compounds For example, cis-1,2-dibromocyclopentane (shown in the first figure) is meso because a plane cuts the molecule into two halves that are reflections of each other. Trans-1,2-dibromocyclopentane, however, is chiral because no plane splits the molecule into two mirror-image halves. Now look at the mirror images of these two molecules in the second figure to prove this generality to yourself. The mirror images of achiral (meso) and chiral molecules Even though the cis compound has two chiral centers (indicated with asterisks), the molecule is achiral because the mirror image is identical to the original molecule (and is, therefore, superimposable on the original molecule). Molecules with planes of symmetry will always have superimposable mirror images and will be achiral. On the other hand, the trans stereoisomer has no plane of symmetry and is chiral. In organic chemistry, you need to be able to spot planes of symmetry in molecules so you can determine whether a molecule with chiral centers will be chiral or meso. For example, can you spot the planes of symmetry in each of the meso compounds shown in the last figure? Some meso compounds How to Identify the Diastereomers of a Molecule When more than one chiral center is present in a molecule, you have the possibility of having stereoisomers that are not mirror images of each other. Such stereoisomers that are not mirror images are called diastereomers. Typically, you can only have diastereomers when the molecule has two or more chiral centers. The maximum number of possible stereoisomers that a molecule can have is a function of 2n, where n is the number of chiral centers in the molecule. Therefore, a molecule with five chiral centers can have up to 25 or 32 possible stereoisomers! As the number of chiral centers increases, the number of possible stereoisomers for that compound increases rapidly. For example, the molecule shown here has two chiral centers. A molecule with two chiral centers Because this molecule has two chiral centers, it can have a total of 22, or 4, possible stereoisomers, of which only one will be the enantiomer of the original molecule. Enantiomers are stereoisomers that are mirror images of each other. Because both chiral centers in this molecule are of R configuration, the enantiomer of this molecule would have the S configuration for both chiral centers. All the stereoisomers of this molecule are shown in the next figure. Those molecules that are not enantiomers of each other are diastereomers of each other. The four stereoisomers of a molecule with two chiral centers

Article / Updated 07-05-2023

Plant cells communicate with each other via messengers called hormones, chemical signals produced by cells that act on target cells to control their growth or development. Plant hormones control many of the plant behaviors you’re used to seeing, such as the ripening of fruit, the growth of shoots upward and roots downward, the growth of plants toward the light, the dropping of leaves in the fall, and the growth and flowering of plants at particular times of the year. Five categories of hormones control plant growth and development: Auxins stimulate the elongation of cells in the plant stem and phototropism (the growth of plants toward light). If a plant receives equal light on all sides, its stem grows straight. If light is uneven, then auxin moves toward the darker side of the plant. This may seem backward, but when the shady side of the stem grows, the stem, in its crookedness, actually bends toward the light. This action keeps the leaves toward the light so photosynthesis can continue. Gibberellins promote both cell division and cell elongation, causing shoots to elongate so plants can grow taller and leaves can grow bigger. They also signal buds and seeds to begin growing in the spring. Cytokinins stimulate cell division, promote leaf expansion, and slow down the aging of leaves. Florists actually use them to help make cut flowers last longer. Abscisic acid inhibits cell growth and can help prevent water loss by triggering stomates to close. Plant nurseries use abscisic acid to keep plants dormant during shipping. Ethylene stimulates the ripening of fruit and signals deciduous trees to drop their leaves in the fall. Fruit growers use ethylene to partially ripen fruit for sale. Some of the flavor-making processes that occur in fruits happen while the fruits are still on the plant. So, even though ethylene can trigger some parts of ripening, like softening after a fruit has been picked, fruit that’s picked unripe doesn’t taste as good as fruit that has ripened on the plant. That’s why you can buy a big, beautiful tomato at the grocery store and take it home only to discover that it doesn’t have much flavor — it was probably picked unripe and then treated with ethylene. If you have houseplants that are growing in bent shapes toward the window, you’re seeing the effect of the hormone auxin at work. The auxin is collecting on the shady side of your plants’ stems, and those cells are growing longer, pushing the stems toward the light. To keep your plants evenly shaped, rotate them occasionally. If your plants are growing really long and thin, they may not have enough light in the place you put them. If all parts of the stem are too shaded, the auxin will make all sides of the stems grow long and thin. This can make the plants very fragile and they may not have enough light for photosynthesis. If they seem yellowish, that’s another clue.